Thumbnail Image

Professor Jayashankar Telangana State Agricultural University, Hyderabad (Telangana State)

Browse

Reset filters
Thesis Type: Ph.D × Subject: Genetics and Plant Breeding ×
Reset filters

Search Results

Now showing 1 - 9 of 239
  • Thumbnail Image
    ThesisItemOpen Access
    GENETIC ANALYSIS OF GRAIN YIELD, ITS CONTRIBUTING CHARACTERS AND STEM BORER RESISTANCE IN MAIZE (Zea mays L.)
    (PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-07-02) Praveen Kumar, G.; FARJANA JABEEN
    The present investigation “Genetic analysis of grain yield, its contributing characters and stem borer resistance in maize (Zea mays l.)” had been undertaken in maize to carry out the combining ability analysis and to estimate heterosis as well as to understand nature of gene action for grain yield, its contributing characters and components which contribute to stem borer resistance. Character association, G X E interaction and stability of experimental hybrids for yield and yield components was studied. The data was collected on days to 50 per cent tasseling, days to 50 per cent silking, days to maturity, plant height (cm), ear height (cm), ear girth (cm), ear length (cm), number of kernel rows per ear, number of kernels per row, 100-kernel weight (g) shelling percentage, grain yield per plant leaf injury rate and dead heart percentage. Twenty seven diverse maize genotypes were screened for their reaction to maize stem borer, Chilo partellus under artificial infestation during Kharif, 2018. Out of the 27 inbred lines screened under artificial infestation, three were found to be resistant to Chilo partellus with leaf injury rating (LIR) score less than 3.0, while 13 were moderately resistant and 11 were highly susceptible. Based on reaction to C. partellus, eight parents were selected and crossed in a diallel fashion excluding reciprocals (Griffings method-II, model-I) during Rabi 2018- 19 and the resulting 28 crosses along with 8 parents and 3 checks, viz., NK-6240 , DHM-117 and CMH-8-287 were evaluated in Randomized Block Design with three replications at three locations viz., Rudrur, Rajendranagar and Hyderabad during kharif, 2019 and the same 28 single crosses along with parents were screened against Chilo partellus under artificial infestation condition simultaneously at Winter Nursery Centre, Rajendranagar, Hyderabad during kharif, 2019 and F2 generation of one cross (resistant × susceptible combination) was evaluated against Chilo partellus during kharif, 2020. The pooled analysis of variance for combining ability revealed significant differences due to environments, parents, hybrids and various interactions indicating the existence of wider variability in the material studied. The ratios of GCA/SCA variances revealed preponderance of non-additive gene action for all of the traits favouring for the exploitation of heterosis breeding. Combining ability analysis revealed that among the parents, CM-139 and DMRDMRE-63 were found to be good general combiners for earliness viz., days to 50 per cent tasseling, days to 50 per cent silking and days to maturity. While,The parents Bio-688, BML-6 and DML-1432 were found to be good general combiners for grain yield and other its directly related traits. These parents had resulted in the production of superior single crosses BML-6 × PFSR-46, BGS-337 × Bio-688, Bio-688 × PFSR-46 and BML-6 × Bio-688 for grain yield per plant. Hence, these inbred lines have potential application in the crop improvement programmes. High specific combining ability effects for grain yield per plant were noticed in the cross combinations BML-6 × PFSR-46, BGS-337 × Bio-688, Bio-688 × PFSR-46 and BML-6 × Bio-688 which can be considered as good specific combiners and genetically worthy crosses as they were superior for yield and important yield contributing characters. The hybrid BML-6 × PFSR-46 recorded significant positive standard heterosis over three standard checks CMH-8-287, NK-6240 and DHM-117. The highest standard heterosis for grain yield per plant was recorded for hybrids BML-6 × PFSR-46, BML-6 × Bio-688 and BGS-337 × Bio-688 along with per se and high sca effects. These hybrids may be further exploited in multilocation evaluation over seasons before releasing them for commercial cultivation. Results of stability analysis revealed that three hybrids viz., BML-6 x Bio-688, Bio-688 × Saf91x2#7 and BML-6 × Saf91x2#7 are identified as stable and best performing hybrids with grain yield 196.14 g, 181.04 g, 170.37 g per plant hence, suitable for wider environments. The investigation on correlation suggesting that selection of promising genotypes for ear length, plant height, ear height, ear diameter, number of rows per kernel, number of kernels per row and 100 kernel weight may be accompanied by increasing grain yield of maize as they had highly significant positive association with grain yield. The path coefficient analysis clearly emphasized the need for selection of ideal genotypes with greater number of kernels per row, ear length, shelling percentage, 100 kernel weight, ear height and number of kernel rows per ear as these were found to be the important traits with direct effect on grain yield. Based on combining ability studies on components that contribute to resistance to spotted stem borer, Chilo partellus, among the parents, DMRE-63, Saf91×2#-7 and Bio-688 were good general combiners for stem borer resistance as they exhibited negative gca effects for leaf injury rate and dead heart percentage. While the hybrids, BML-6 × Bio-688, CM-139 × PFSR-46, CM-139 × BML-6, BGS-337 × BML-6, PFSR 46 × DMRE-63 and BML-6 × Saf91×2#-7 were good specific combiners for stem borer resistance as they exhibited negative sca effects for both the studied traits. The F2 population study of cross, BML-6 × DMRE-63 (Susceptible × Resistance) indicated a monogenic dominant gene inheritance for leaf injury rate in the cross BML-6 × DMRE 63 (Susceptible × Resistance), which needs to be further verified through F3 population study. Keeping in view of the above facts, by considering all factors like per se performance, sca effect, standard heterosis and stability the most promising hybrids identified were BML-6 × Bio-688, BML-6 × PFSR-46, BGS-337 × Bio-688 and Bio 688 × Saf91×2#-7 in which, BML-6 × Bio-688 and Bio-688 × Saf91×2#-7 were least susceptible to stem borer. These identified promising cross combinations are to be tested extensively over different agro climatic zones and across the years for their superiority and stability before commercial release and were may be advanced for selfing for the isolation of transgressive segregants or homozygous lines for use in breeding programmes.The present investigation “Genetic analysis of grain yield, its contributing characters and stem borer resistance in maize (Zea mays l.)” had been undertaken in maize to carry out the combining ability analysis and to estimate heterosis as well as to understand nature of gene action for grain yield, its contributing characters and components which contribute to stem borer resistance. Character association, G X E interaction and stability of experimental hybrids for yield and yield components was studied. The data was collected on days to 50 per cent tasseling, days to 50 per cent silking, days to maturity, plant height (cm), ear height (cm), ear girth (cm), ear length (cm), number of kernel rows per ear, number of kernels per row, 100-kernel weight (g) shelling percentage, grain yield per plant leaf injury rate and dead heart percentage. Twenty seven diverse maize genotypes were screened for their reaction to maize stem borer, Chilo partellus under artificial infestation during Kharif, 2018. Out of the 27 inbred lines screened under artificial infestation, three were found to be resistant to Chilo partellus with leaf injury rating (LIR) score less than 3.0, while 13 were moderately resistant and 11 were highly susceptible. Based on reaction to C. partellus, eight parents were selected and crossed in a diallel fashion excluding reciprocals (Griffings method-II, model-I) during Rabi 2018- 19 and the resulting 28 crosses along with 8 parents and 3 checks, viz., NK-6240 , DHM-117 and CMH-8-287 were evaluated in Randomized Block Design with three replications at three locations viz., Rudrur, Rajendranagar and Hyderabad during kharif, 2019 and the same 28 single crosses along with parents were screened against Chilo partellus under artificial infestation condition simultaneously at Winter Nursery Centre, Rajendranagar, Hyderabad during kharif, 2019 and F2 generation of one cross (resistant × susceptible combination) was evaluated against Chilo partellus during kharif, 2020. The pooled analysis of variance for combining ability revealed significant differences due to environments, parents, hybrids and various interactions indicating the existence of wider variability in the material studied. The ratios of GCA/SCA variances revealed preponderance of non-additive gene action for all of the traits favouring for the exploitation of heterosis breeding. Combining ability analysis revealed that among the parents, CM-139 and DMRDMRE-63 were found to be good general combiners for earliness viz., days to 50 per cent tasseling, days to 50 per cent silking and days to maturity. While,The parents Bio-688, BML-6 and DML-1432 were found to be good general combiners for grain yield and other its directly related traits. These parents had resulted in the production of superior single crosses BML-6 × PFSR-46, BGS-337 × Bio-688, Bio-688 × PFSR-46 and BML-6 × Bio-688 for grain yield per plant. Hence, these inbred lines have potential application in the crop improvement programmes. High specific combining ability effects for grain yield per plant were noticed in the cross combinations BML-6 × PFSR-46, BGS-337 × Bio-688, Bio-688 × PFSR-46 and BML-6 × Bio-688 which can be considered as good specific combiners and genetically worthy crosses as they were superior for yield and important yield contributing characters. The hybrid BML-6 × PFSR-46 recorded significant positive standard heterosis over three standard checks CMH-8-287, NK-6240 and DHM-117. The highest standard heterosis for grain yield per plant was recorded for hybrids BML-6 × PFSR-46, BML-6 × Bio-688 and BGS-337 × Bio-688 along with per se and high sca effects. These hybrids may be further exploited in multilocation evaluation over seasons before releasing them for commercial cultivation. Results of stability analysis revealed that three hybrids viz., BML-6 x Bio-688, Bio-688 × Saf91x2#7 and BML-6 × Saf91x2#7 are identified as stable and best performing hybrids with grain yield 196.14 g, 181.04 g, 170.37 g per plant hence, suitable for wider environments. The investigation on correlation suggesting that selection of promising genotypes for ear length, plant height, ear height, ear diameter, number of rows per kernel, number of kernels per row and 100 kernel weight may be accompanied by increasing grain yield of maize as they had highly significant positive association with grain yield. The path coefficient analysis clearly emphasized the need for selection of ideal genotypes with greater number of kernels per row, ear length, shelling percentage, 100 kernel weight, ear height and number of kernel rows per ear as these were found to be the important traits with direct effect on grain yield. Based on combining ability studies on components that contribute to resistance to spotted stem borer, Chilo partellus, among the parents, DMRE-63, Saf91×2#-7 and Bio-688 were good general combiners for stem borer resistance as they exhibited negative gca effects for leaf injury rate and dead heart percentage. While the hybrids, BML-6 × Bio-688, CM-139 × PFSR-46, CM-139 × BML-6, BGS-337 × BML-6, PFSR 46 × DMRE-63 and BML-6 × Saf91×2#-7 were good specific combiners for stem borer resistance as they exhibited negative sca effects for both the studied traits. The F2 population study of cross, BML-6 × DMRE-63 (Susceptible × Resistance) indicated a monogenic dominant gene inheritance for leaf injury rate in the cross BML-6 × DMRE 63 (Susceptible × Resistance), which needs to be further verified through F3 population study. Keeping in view of the above facts, by considering all factors like per se performance, sca effect, standard heterosis and stability the most promising hybrids identified were BML-6 × Bio-688, BML-6 × PFSR-46, BGS-337 × Bio-688 and Bio 688 × Saf91×2#-7 in which, BML-6 × Bio-688 and Bio-688 × Saf91×2#-7 were least susceptible to stem borer. These identified promising cross combinations are to be tested extensively over different agro climatic zones and across the years for their superiority and stability before commercial release and were may be advanced for selfing for the isolation of transgressive segregants or homozygous lines for use in breeding programmes.
  • Thumbnail Image
    ThesisItemOpen Access
    GENETIC ANALYSIS FOR SEED COTTON YIELD AND QUALITY CHARACTERS IN SINGLE, THREE-WAY AND DOUBLE CROSSES OF INTER AND INTRA SPECIFIC HYBRIDS BETWEEN AMERICAN COTTON (Gossypium hirsutum L.) AND EGYPTIAN COTTON (Gossypium barbadense L.)
    (PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-07-02) Prashanth, Y.; Pradeep, T.
    The present study was carried out to develop and evaluate single, three-way and double crosses developed from six inbreds (four genotypes of Gossypium hirsutum L. and two genotypes of Gossypium barbadense L.) and to elicit information on combining ability and the nature of gene action, magnitude of standard heterosis, comparative performance of single, three-way and double crosses, order effects of the parents involved in three-way and double crosses for fourteen yield and fibre quality contributing characters Six promising established inbred lines were crossed in half diallel during Kharif, 2019 at Agricultural Research Station, Adilabad. The resultant 15 F1’s were raised during Summer, 2019 and were involved in crosses with inbreds such that no parent appears twice in the same cross and obtained 60 three-way crosses. Similarly, single crosses were involved in diallel set with restriction that only unrelated crosses were involved in crossing programme and obtained 45 double crosses. The resulting 15 single, 60 three-way, 45 double crosses along with six parents and eighteen public/private checks were evaluated in simple lattice design (12 × 12) for variability, combining ability, heterosis and prediction of double cross performance at ARS, Adilabad during Kharif, 2020. Analysis of variance for all the entries for 14 studied characters indicated the presence of variability among genotypes. Mean sum of squares for all the three types of crosses i.e. single, three-way and double crosses were highly significant for all the characters except the trait uniformity ratio suggesting the variability among three types of crosses. In diallel, analysis of variance revealed that mean squares were highly significant for all the 14 traits except uniformity ratio, indicating that these traits were highly influenced by environmental factors. Significant differences among the parents and single cross hybrids inferred considerable variation among the parents as well as the hybrids for all the traits except ginning outturn (GOT%) and uniformity ratio. This suggested that the parents transmitted their variable potential to their crosses for a majority of the traits. All the characters showed non additive gene action except days to 50 per cent flowering and GOT%, indicating preponderance of non additive gene action in the inheritance of all the characters studied. Triallel analysis showed that all the three types of epistatic components viz., additive × additive, additive × dominance, dominance × dominance, in addition to the additive and dominance gene actions played a major role in the expression of all fourteen traits studied. The analysis of variance of quadriallel showed that dominance variance was found to be more than additive variance for all the traits except micronaire, uniformity ratio and seed cotton yield plant-1 . Among the epistatic interactions, dominance × dominance interaction was predominant for all the traits except uniformity ratio and seed cotton yield plant-1 . Additive × additive interaction was predominant for seed cotton yield plant-1 whereas, additive × dominance interaction for uniformity ratio. For all the traits except plant height, number of monopodia plant-1 , micronaire, uniformity ratio and seed cotton yield plant-1 additive × additive × additive interactions were very high. Presence of additive, additive × dominance, additive × additive and dominance × dominance gene actions in three-way and double crosses suggest that, the trait improvement would be possible by adopting special breeding methods like inter mating in early segregating generations for two to three generations followed by pedigree method of breeding or recurrent selection schemes. Among all 120 hybrids studied, one single cross i.e., ARBC 64 × CNH 115 (36.07%), three-way crosses viz., (Adilabad kapas-1 × ARBC 64) × ADB 39 (34.48%), (ARBC 64 × CNH 115) × Adilabad kapas-1 (33.06%) and (ADB 39 × CNH 115) × Phule rukhmai (28.86%*) and one double cross combination (ADB 39 × ARBC 64) × (Suvin × CNH 115) (25.38%*) was exhibited significant positive standard heterosis over check WGHH-2, whereas none of the hybrid shown significant positive heterosis over check Randheer, fourteen different cross combinations of single (2), three-way (9) and double cross (3) had positive heterosis for seed cotton yield plant-1 . All these fourteen crosses were found to have significantly desirable heterosis for one or more fibre quality traits over check Randheer. Based on the per se performance of seed cotton yield plant-1 (g) with superior fibre quality traits like 2.5% span length, bundle strength and micronaire, the single crosses ADB 39 × Phule Rukhmai (195.29 g), Adilabad kapas-1× Phule Rukhmai (183.80 g) and ARBC 64 × CNH 115 (217.82 g) had standard heterosis of 22.00%, 14.82% and 36.07%** over check WGHH-2 with high specific combining ability effects (744.56**, 664.70** and 818.19**, respectively). Among three-way crosses (Adilabad kapas-1× ARBC 64) × ADB 39 (215.27 g), (ARBC 64 × CNH 115) × Adilabad kapas-1(213.00 g) and (ADB 39 × CNH 115) × Phule Rukhmai (206.27 g) had shown standard heterosis of 34.48%*, 33.06%* and 28.86%* with significant 3-line specific combining effects 6.44, 31.27** and 51.55**, respectively over check WGHH 2. In double crosses, [(ADB 39 × ARBC 64) × (Suvin × CNH 115) (200.71 g)], [(ADB 39 × Suvin) × (ARBC 64 × CNH 115) (186.17 g)], [(Adilabad kapas-1× ARBC 64) × (ADB 39 × CNH 115) (176.36 g)] and [(Adilabad kapas-1× CNH 115) × (ADB 39 × ARBC 64) (174.23 g)] having standard heterosis of 25.38%*, 16.29% and 10.17% and four line interaction effects of 4.97, 5.84 and 0.78, respectively over check WGHH-2. Further all the three-way crosses and double crosses had shown significant differences in combining ability effects while changing the orders of a particular combination in all the fourteen characters studied. The predicted seed cotton yield of the double cross hybrids based on single cross and three-way cross performance was found to be higher than the actual in 73% of the hybrids tested. But, only 22% hybrids exhibited lower yield than actual when predicted by Dt-s . The correlation coefficient between actual and predicted performance based on D s , Dt and Dt-s was 1.49, 2.19 and 1.80, respectively significant correlation was observed to be predicted only by the three way crosses. The findings of the present investigation clearly suggest that none of the eight interspecific hybrids exhibited significantly superior standard heterosis over the intra hirsutum hybrids for yield. However, quality parameters were found to be desirable in interspecific hybrids indicating that priority must be given to achieve proper balance between yield and quality aspects in future cotton breeding programmes. Plant breeding methods that deviate from the normal pedigree method need to be employed to develop genotypes/hybrids combined with yield and desirable quality characters. Appropriate cross combinations identified in each class of hybrids such as ADB 39 × Phule rukhmai , Adilabad kapas-1 × Phule rukhmai and ARBC 64 × CNH 115 single crosses, (Adilabad kapas-1 × ARBC 64) × ADB 39, (ARBC 64 × CNH 115) × Adilabad kapas-1 and (ADB 39 × CNH 115) × Phule rukhmai three-way crosses and (ADB 39 × ARBC 64) × (Suvin × CNH 115), (ADB 39 × Suvin) × (ARBC 64 × CNH 115), (Adilabad kapas-1 × ARBC 64) × (ADB 39 × CNH 115) and (Adilabad kapas-1 × CNH 115) × (ADB 39 × ARBC 64) double crosses can be subjected to different mating systems and the resultant progenies can be exploited for identification of superior cotton genotypes possessing both quality and yield
  • Thumbnail Image
    ThesisItemOpen Access
    MOLECULAR MAPPING AND VALIDATION OF QTLs ASSOCIATED WITH RESISTANCE TO APHID (Uroleucon compositae THEOBALD) IN SAFFLOWER (Carthamus tinctorius L.)
    (PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-09-22) Divya, K.; Hemalatha, V.
    Safflower is an important oilseed crop in India; its productivity is affected by many biotic and abiotic stresses. Amongst the various pests, the aphid Uroleucon compositae Theobald, severely affects the crop growth and yield. It is a major insect pest, which causes yield loss ranging from 30 to 80%. Host plant resistance is an effective way of managing the aphid problem in safflower. Tolerance is reported to be a predominant category of resistance against aphid in safflower. Genetic basis of tolerance to aphid in safflower is not understood well. The present study was undertaken to map and validate the previously reported QTLs (a major QTL, QUc-Ct3.1 and a minor QTL, QUc-Ct5.1) for tolerance to aphid (based on the phenotype of days to-wilt after aphid infestation) in different populations (recombinant inbred lines-RIL and backcross-BC1F3) developed from the cross of CO-1 x EC-523368-2. A genetic linkage map of F8 RIL population was constructed using 279 lines with 121 DNA marker (SSR and SNP) loci, which were distributed on 12 linkage groups with total genome coverage of 1292.8 cM. QTL analysis in F8 RIL population using the genotypic data (121 markers) and phenotypic data (days-to-wilt) redetected the major QTL, QUc-Ct3.1 with the flanking markers SafM-1160 and AMPCt-131 on linkage group (LG) 3 [LOD=41.4 and phenotypic variance explained (PVE)=42.6%] and the minor QTL, QUc-Ct5.1 with flanking markers CtDES-237 and AMPCt-55 on linkage group 5 (LOD=9.6 and PVE=8%). In addition, two new putative regions were detected on LG-6 (SaFM-207-AMPCt-93; LOD=3.3; PVE=3.7%) and LG-9 (AMPCt-208- SaFM-273; LOD=5.2; PVE=4.3%). The major QTL (QUc-Ct3.1) region on LG-3 was fine-mapped with the addition of three markers including a SNP marker, AMPCt-131 and two SSRs: SafM-1160 and SafM-1137 in the QTL region. Based on this, a set of seven markers, SafM-1160, SafM-1137, SafM-290, SafM-23, CAT-85, CtDES-237 and AMPCt-131, linked to the QTLs, QUc-Ct3.1 and QUc-Ct5.1 were selected for validation of the QTLs in different generations, F10/F11 RILs and BC1F3 of CO-1 x EC 523368-2 cross. The F10 RILs (239) and BC1F3 (206) populations were phenotyped based on days-to-wilt and chlorophyll content after aphid infestation at ICAR-IIOR, Hyderabad during rabi-2019. Single marker analysis of the QTL linked markers with days-to-wilt and chlorophyll content in F10 RILs and BC1F3 populations revealed that major QTL (QUc-Ct3.1) linked markers, SafM-1160 and SafM-1137 showed strong association with days-to-wilt explaining 49% and 40% of phenotypic variance, respectively in F10 RILs and, 36% and 37% in BC1F3 lines, respectively. The same major QTL linked markers (AMPCt-131, SafM-1160 and SafM-1137) also showed strong association with chlorophyll content (measured as difference of SPAD values between time point 1 and 4) explaining phenotypic variance of 47%, 67.5% and 52.1%, respectively in F10 and 16.1%, 35.2% and 36.9%, respectively in BC1F3 populations. Furthermore, the same major QTL linked markers (AMPCt-131, SafM-1160 and SafM-1137) showed strong association with biomass in F11 population explaining phenotypic variance of 10%, 42% and 40%, respectively. Composite interval mapping of chlorophyll content of F10 RILs using F6 and F8 maps also detected a major QTL, which co-localized with the major QTL region. These results clearly demonstrated that the major aphid tolerant QTL QUc Ct3.1 could be repeatedly detected across different generations of CO-1 x EC-523368-2 cross with different tolerance related phenotypes such as days-to-wilt, chlorophyll content and biomass under aphid infestation. Furthermore, the F9 and F10 RIL populations were phenotyped for yield related traits viz., days to 50% flowering, plant height, number of primary capitula per plant, number of seeds per primary capitula and seed yield under no aphid condition. Analysis of variance revealed significant differences among all the traits indicating considerable variability in the mapping populations. QTL analysis detected a single putative QTL for days to 50% flowering (qDFF-3.1) in F6:9 while two putative QTLs each for days to 50% flowering (qDFF-8.1) and number of seeds/primary capitulum (qNSP-3.1) were detected in F6:10 population. Similarly, three putative QTLs for days to 50% flowering, plant height (qPH-3.1) and hundred seed weight (qHSW-6.1) in F8:9 population and two putative QTLs for plant height (qPH-3.1 and qPH-9.1) and a single QTL for number of primary capitula/plant (qNPCP-5.1) in F8:10 population. It was observed that the QTL for days to 50% flowering and plant height co-localized with the major QTL (QUc Ct3.1) but found inconsistent (detected only in single environment or in single generation). Two plant defense related candidate like genes, LOC111889729 (polyphenol oxidase) from Lactuca sativa (lettuce) and LOC110890449 (polyphenol oxidase 1) from Helianthus annus (sunflower) were mapped on to chromosome 3 of safflower reference genome, with about 2 cM distance from the linked markers of major QTL (QUc-Ct3.1), which require further investigation towards tracing the candidate gene underlying the major aphid tolerant QTL validated in this study.
  • Thumbnail Image
    ThesisItemOpen Access
    DEVELOPMENT OF HYBRIDS RESISTANT TO BLAST AND COLD SUITABLE FOR RABI SEASON IN RICE (Oryza sativa L.)
    (PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-09-22) Gonya Nayak, P.; Sujatha, M.
    The present investigation entitled “Development of hybrids resistant to blast and cold suitable for rabi season in rice (Oryza sativa L.)” was conducted to identify blast and cold tolerant hybrids and to study the combining ability, heterosis and stability analysis for grain yield and its components. During kharif 2019, twenty restorer lines and four Cytoplasmic Male Sterile lines are selected and developed 80 hybrids. These hybrids along with parental lines and suitable checks were screened against cold and blast at RARS, Jagtial and Rice Research Centre, ARI, Rajendranagar during rabi 2019-20. During the nursery growth stage the crop was exposed to both normal and low temperature stress both at RNR & JGL with average minimum temperature of 17.3 0C and 12.90C during previous five days duration of recording SPAD observations. Accordingly percentage decrease in SPAD reading was recorded and data revealed that, among the 80 hybrids screened for cold stress, 19 hybrids recorded less than 10 percent decrease of SPAD readings and 55 hybrids recorded 10-20 percent decrease of SPAD readings indicating their strongly tolerant and tolerant reaction for low temperature stress. However, 6 hybrids were identified as moderately tolerant with 20-30 percent decrease in SPAD reading. Similarly yellowing score was recorded when the nursery was exposed to low temperature stress. Baring two testers (TP 30211 and JGL 33508) all the parents had recorded either strongly tolerant or tolerant reaction for cold stress. Among the hybrids, 19 hybrids recorded 0-1 score with strongly tolerant reaction, 55 hybrids recorded 2-3 score with tolerant reaction and 6 hybrids recorded moderately tolerant reaction with 4-5 score. In susceptible checks yellowing score was recorded 7 in JGL 11470, JGL 1798 and in tolerant checks like JGL 24423 recorded 2 score and Tellahamsa recorded 3 score. In case of blast, disease incidence was almost similar among the locations. The blast incidence was severe in susceptible check, TN1 whereas in resistant check, NLR 34449 the lesions were not observed, which clearly indicate that the incidence of disease pressure was very good and scoring is reliable. Out of 104 entries screened for leaf blast 73 entries were identified as resistant (R), 21 lines were moderately resistant (MR) whereas 10 lines identified as susceptible. Based on phenotypic screening, 10 restorer lines viz., RNR 26085, ZGY 1, RNR 2354, RNR 28359, RNR 21571, IR 72, JGL 35126, JL 35047, JGL 34551, RNR 28411 and their hybrid combinations were identified as resistant through uniform blast nursery and cold nursery screening methods. During kharif 2020, ten restorer lines possessing resistance to leaf blast and cold tolerance were crossed on to four CMS lines in Line × Tester mating design and produced 40 experimental hybrids at RARS, Jagtial. The resultant 40 hybrids along with their parents, two checks (US 314 and Tellahamsa) were evaluated for combining ability, heterosis and stability analysis at three locations representing two agro climatic zones of Telangana State viz., Jagtial and Rudrur (Northern Telangana Zone) and Rajendranagar (Southern Telangana Zone) during rabi 2020-21. The pooled analysis of variance for combining ability over locations revealed presence of significant differences among the locations, parents and crosses which indicated the existence of adequate variation in the material under studied. The ratio of gca to sca variances indicated that non-additive gene action was most prevalent for most of the characters under study. Combining ability analysis revealed that the line, CMS 59B and among the testers, ZGY 1, RNR 2354, RNR 28359 and JGL 35126 were identified as promising based on their gca effects for grain yield per plant and other important yield contributing characters. Based on significant sca effects 16 hybrids were identified as promising for grain yield per plant. Similarly for standard heterosis, the range was from -24.48 (CMS 46A × RNR 21571) to 32.52 per cent (JMS 13A × RNR 2354) and positive significant standard heterosis exhibited by 14 hybrids for grain yield per plant over hybrid check, US 314. Six superior combinations viz., JMS 13A × RNR 2354, CMS 46A × JGL 34551, JMS 13A × ZGY 1, CMS 59A × IR 72, CMS 59A × JGL 35126 and CMS 59A × ZGY 1 have been identified as promising hybrids based on per se performance, positive sca effects and standard heterosis for yield and its attributes. Results of pooled analysis of variance for stability revealed that the genotypes were significant for all the characters whereas environments are significant for majority of characters except kernel breadth, indicating the existence of diversity among the genotypes and environments. The G × E interaction was significant for the characters viz., grain yield per plant, plant height, number of productive tillers, spikelet fertility and milling percentage indicating differential behaviour of genotypes under three locations for these characters. The estimate of environmental indices indicated that Rudrur was best favourable location for majority of the characters including grain yield per plant. Based on stability analysis, three hybrids viz., JMS 13A × RNR 2354, CMS 49A × JGL 34551 and JMS 13A × ZGY 1 were identified as stable hybrids for grain yield per plant and other traits
  • Thumbnail Image
    ThesisItemOpen Access
    GENOME-WIDE ASSOCIATION ANALYSIS FOR GRAIN YIELD AND QUALITY TRAITS INRICE (Oryza sativa L.)
    (PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2021-07-01) Shivani, D.; Farzana Jabeen
    Rice (Oryza sativa L.) is one of the most important agricultural crop and the main staple food of various countries of the Asia continent. Currently, breeding for rice faces the problem of yield plateaus, as we witness declining rice productivity in many countries. Increase in human population growth, particularly in developing countries where rice is the main source of caloric intake, coupled with climate change and the intensive water, land, and labor requirements of rice cultivation creates a pressing and continuous global need for new, enhanced quality, resource-use efficient and highly productive rice varieties. Hence, detection and mapping of quantitative trait loci (QTL’s) for yield and quality traits have been looked upon as an efficient way of improving the yield and quality potential of rice varieties. The present study Genome-wide association analysis for grain yield and quality traits in rice (Oryza sativa L.) was conducted during Kharif 2019, 2020 and Rabi 2019-20, 2020-21 at ICAR-Indian Institute of Rice Research, Rajendranagar, Hyderabad with the aim of carrying out phenotypic evaluation and association mapping in 72 germplasm lines of rice. Phenotypic evaluation of the germplasm was carried out in an Randomized Block Design replicated twice. Genome Wide Association Study (GWAS) was carried out using GAPITv.3 and identification of QTLs was performed from QTARO Database (qtaro.abr.affrc.go.jp) and Gramene database (www.gramene.org). The data was collected on yield and quality traits i.e. days to 50% flowering, plant height at maturity (cm), panicle length (cm), number of tillers per plant, number of productive tillers per plant, panicle weight (g), number of filled grains per panicle, number of unfilled grains per panicle, test weight (g), single plant yield (g), hulling (%), milling (%), head rice recovery, kernel length, kernel breadth, length/breadth ratio, grain type, grain chalkiness, alkali spreading value, amylose content, gel consistency and gelatinization temperature. Traits such as number of filled grains per panicle, number of unfilled grains per panicle and panicle weight exhibited higher genotypic and phenotypic coefficient of variation during Kharif 2019, 2020 indicating the existence of wider genetic variability for these traits among the germplasm lines studied. High heritability coupled with high genetic advance was recorded for all the traits except panicle length during Kharif 2019, 2020 indicating the preponderance of high additive gene action involved in governing these traits, simple and directional selection is sufficient to further improvement. Among the traits studied days to fifty percent flowering, panicle weight and number of filled grains per panicle exhibited positive significant association with grain yield per plant indicating indirect selection for these component traits might improve the grain yield directly. Number of tillers per plant exerted the highest positive direct effect on grain yield followed by panicle weight, panicle length, number of unfilled grains per panicle, days to 50 per cent flowering, number of filled grains per panicle and test weight indicating that the selection for these characters was likely to bring about an overall improvement in grain yield per plant directly. Studies on variability for quality traits indicated that phenotypic and genotypic coefficients of variation were high for alkali spreading value and gel consistency during Rabi 2019-20 and Rabi 2020-21. PCV estimates were slightly higher than the corresponding GCV estimates for all the characters with very narrow range which showed less influence of environment. High heritability coupled with high genetic advance was recorded for kernel length, kernel breadth, kernel length/breadth ratio, alkali spreading value and gel consistency during Rabi 2019-20, 2020-21 indicating the preponderance of high additive gene action involved in governing these traits, simple and directional selection is sufficient to further improvement. With respect to the molecular diversity studies for population structure analysis, the germplasm lines was grouped into eight clusters based on the polymorphism of the SSR markers. Thus, these germplasm lines of different clusters indicate genetically diverse and feasible for association mapping studied. GWAS through GAPIT revealed 2,67,992 of nucleotides in the DNA of germplasm lines of rice. In the entire germplasm lines studied, Guanine, Cytosine, Adenine and Thymine accounted for 24.53 percent, 22.59 percent, 21.67 percent and 19.44 percent respectively. Highest number of single nucleotide changes occurred from G to A (15.41%) followed by C to T (16.52%), A to G (15.41%) and T to C (13.63%). The total number of SNPs detected were 3,944 which are used for GWAS across the genome. The 72 germplasm lines was genotyped using Illumina rice 7K Chip, International Rice Research Institute. The genotypic data and phenotypic data have been used for genome wide association studies in GAPIT v.3 programme and the Population structure analysis using STRUCTURE 2.3.3 revealed that these germplasm lines were stratified into five sub-populations. GWAS using MLM analysis identified 7 already reported quantitative trait loci for yield and quality traits through GAPIT. 3 QTLs viz., dth1.1, Hd7 and dth8 located on chromosomes 1, 2 and 8 respectively were identified for days to 50% flowering. One QTL on chromosome 9 (pl9) was identified for panicle length. One QTL (amy6-1) for amylose content, one QTL (asv6-1) on chromosome 6 for alkali spreading value and one QTL (qGC-6) for gel consistency were detected. However, there are certain peaks on different chromosomes for all traits for which QTLs were not known. Hence, the peaks with significant SNPs were identified as novel QTLs. Nine QTLs (qDFF2, qDFF3, qDFF4, qDFF4-1, qDFF7, qDFF8, qDFF9, qDFF12 and qDFF12-1) for days to 50% flowering, eighteen QTLs (qPL1, qPL5, qPL5-1, qPL5-2, qPL5-3, qPL5-4, qPL6, qPL6-1, qPL12, qPL12-1, qPL12-2, qPL12-3, qPL12-4, qPL12-5, qPL12-6, qPL12-7, qPL12-8 and qPL12- 9) for panicle length, three QTLs (qNT7, qNT7-1 and qNT11) for total number of tillers per plant, two QTLs (qNPT7 and qNPT7-1) for total number of productive tillers per plant, two QTLs (qPW2 and qPW12) for panicle weight, three QTLs (qNFG2, qNFG2-1 and qNFG3) for number of filled grains per panicle, one QTL (qGY4) for grain yield per plant, one QTL (qH5) for hulling percent, one QTL (qMRR1) for milling, one QTL (qHRR12) for HRR, three QTLs (qKL12, qKL12-1 and qKL3) for kernel length, four QTLs (qKB10, qKB6, qKB11 and qKB6-1) for kernel breadth, one QTL (qKLB3) for kernel length/breadth, one QTL (qCH1) for grain chalkiness, qAC1 for amylose content, two QTLs (qGC4 and qGC7) for gel consistency and one QTL (qGT8) for grain type were identified for yield and quality traits. Hybridization for introgression of identified yield related QTLs was carried out using two female parents (Jaya and WGL-14) and one common male parent (Pushyami) having more number of filled grains per panicle with positive allele for QTLs, qNFG3 and qNFG2 on chromosome 3, 2 associated with SNPs SNP-3.3850394, SNP-2.9243436 respectively. The hybridity of the F1 plants was confirmed using polymorphic SSR markers RM12833 and RM13020. Out of the ten F1 plants (Jaya X Pushyami), three plants showed amplified bands for both the parents when analyzed at molecular level. Similarly, with respect to other cross (WGL-14×Pushyami), 3 out of the 6 F1 plants showed allelic bands for both the parents. These confirmed F1 plants will be utilized further to backcross to develop BC1F1 seeds by MABB for the improvement of grain number per panicle. The identified QTLs are directly applicable for introgression through marker assisted selection and the present work forms a valuable platform and long-term collective effort to discover valuable genes from the germplasm collection for the genetic improvement of yield and quality traits. Further, the study provides a direction for breeding efforts in the selection of parents from the current germplasm collection with potential for novel QTLs for important of yield and quality traits.
  • Thumbnail Image
    ThesisItemOpen Access
    STABILITY ANALYSIS OF WILD INTROGRESSION LINES IN RICE USING AMMI AND GGE BIPLOT ANALYSES
    (PROFFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2021-07-01) De Silva, N. P. S.; Gouri Shankar, V.
    The present investigation was done using 151 recombinant inbred lines (RILs) derived from a cross between Swarna and 166s (an advanced backcross introgression line developed at Indian Institute of Rice Research (IIRR), Rajendranagar, Hyderabad from a cross between Swarna x O. nivara) aiming to identify high yielding lines with wild introgressions. The main objective of the study was to analyze the stability and adaptability of the rice lines using AMMI and GGE biplot models. The 151 RILs were evaluated with Swarna and 166s as parental checks in three seasons viz., Rabi 2017-18, Rabi 2018-19 and Kharif 2019 of F5, F6 and F7 generations for yield and yield traits viz., plant height (PH), number of total tillers per plant (TN), number of productive tillers per plant (PTN), thousand-grain weight (TGW), single plant grain yield (SPY) and biomass weight per plant (BM). The experiment was laid out in a Randomized Complete Block Design with two replications at IIRR, Hyderabad. Parental polymorphism between the parents of this mapping population was also studied using 135 SSR markers for further QTL mapping. Character association and path analysis were studied for the above-mentioned yield-related traits of three season’s pooled data. Analysis of variance indicated the existence of significant genotypic differences among the genotypes for all the characters studied. In three seasons broad phenotypic variation was observed and genotypic average ranged for PH (72.14 to 104.24); TN (10.45 to 20.10); PTN (9.9 to 19.17); SPY (13.6 to 31.44); TGW (17.08 to 24.57); BM (10.78 to 33.73) among the genotypes under study. Pooled analysis over three season’s data revealed that among all the genotypes tested; the shortest genotype was G5 and the tallest genotype was G12. The lowest and highest number of total tillers per plant and productive tillers per plant was observed in G89 and G2 respectively.The genotype G5 recorded the lowest single plant grain yield and G14 scored the highest. Among the genotypes investigated genotype G41 showed the lowest 1000-grain weight followed by G153 (Swarna). The highest 1000-grain weight was shown by G76. Among the genotypes investigated G80 recorded lowest biomass weight per plant and the maximum was recorded by G84. Combined analysis of variance for the data by AMMI and GGE models showed significant genotype, environment and genotype x environment interaction except for traits viz., total tiller number per plant, productive tiller number per plant and single plant grain yield where the environment component was not significant, exhibiting the presence of inherent genetic variances among the genotypes and variability among the environments. The result revealed that the 1000-grain weight and plant height were contributed mainly by genotypic effect revealing that the 1000-grain weight and plant height were the most stable traits across the seasons with minimal genotype variation. But the traits viz., total tiller number per plant (41.1%), productive tiller number per plant (41.03%), single plant grain yield (42.61%) and biomass weight per plant (46.18%) were mostly affected by genotype by environment interaction. According to AMMI and GGE models, the PC1 values were higher than PC2 values for all the traits studied and explained the higher contribution of genotype in the total sum of squares of the genotype x environment interaction. According to AMMI model, the highest PC1 value was observed in biomass weight per plant (76%), followed by single plant grain yield (61.3%), thousand-grain weight (60.1%), productive tiller number per plant (58.8%), total tiller number per plant (56%) and plant height (54%). According to GGE model, the highest PC1 value was observed in 1000-grain weight (83.4%) followed by plant height (74.6%), biomass weight per plant (65.7%), productive tiller number per plant (47.9%), total tiller number per plant (46.8%) and single plant grain yield (43.5%). As per AMMI biplot analysis, the season Kharif 2019 was the best-suited environment for potential expression of most of the traits investigated in present study viz., plant height, biomass weight per plant, productive number of tillers per plant, 1000-grain weight and single plant grain yield. The genotype G65 was identified as the stable and adaptable most suited line across all three seasons for single plant grain yield; G30 for plant height; G50 for total tiller number and productive tiller number per plant; G145 for biomass weight per plant and G148, G116 and G76 for 1000-grain weight according to AMMI biplot analysis. According to the GGE biplot genotypic view graph, G14 was identified as the ideal genotype for single plant grain yield; G12 for plant height; G2 for the total tiller number per plant and productive tiller number per plant; G84 for biomass weight per plant; G76, G101 and G84 were identified as the ideal genotypes for high 1000-grain weight. According to the GGE biplot polygon view graph, for single plant yield G14 and G145 were the best suited for Kharif 2019 and Rabi 2018/19 respectively; G12 was the best suited for plant height in Rabi 2017/18 and G136 for Rabi 2018/19 and Kharif 2019; G145 and G2 were the best suited for productive tiller number per plant in Rabi 2017/18 and Kharif 2019 respectively; G44 was the best suited for total tiller number per plant in Rabi 2018/19, G2 for Kharif 2019 and G145 for Rabi 2017/18; G3 was the best suited for biomass weight per plant in Rabi 2018/19, Kharif 2019 and G114 for Rabi 2017/18. G34 was the best suited for 1000-grain weight in Kharif 2019 and G76,G148, G142 for Rabi 2017/18 and Rabi 2018/19. Among the 135 SSR markers used for testing polymorphism between the two parents, Swarna and 166s, 88 markers (65.18%) were polymorphic and distributed across the twelve chromosomes. The character association studies revealed that single plant grain yield had a significant positive association with the number of total tillers per plant, number of productive tillers per plant, biomass weight per plant and plant height. Path coefficient analysis revealed that the number of productive tillers per plant exerted the highest positive direct effect on single plant grain yield followed by biomass weight per plant and plant height. In conclusion, character association and path analysis indicated that the number of productive tillers per plant, biomass weight per plant and plant height displayed significant positive correlation as well as a positive direct effect on single plant grain yield at both genotypic and phenotypic levels. Hence, these traits were considered as important attributes in formulating selection criterion for achieving desired targets.
  • Thumbnail Image
    ThesisItemOpen Access
    GENETIC ANALYSIS FOR YIELD AND SHOOT FLY RESISTANCE IN CMS BASED HYBRIDS OF SORGHUM [Sorghum bicolor (L.) Moench
    (PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-02-07) SAI KIRAN, V; SHIVANI, D
    The present investigation was conducted to study the performance of the 48 hybrids and their parents with respect to grain yield and shoot fly resistance in sorghum. The experiment was conducted using 14 parental lines, which included six females, viz., ICSA 418, ICSA 419, ICSA 427, ICSA 433, ICSA 435 and ICSA 29004 (male sterile, A lines) and eight male lines, ICSR 13004, ICSR 13009, ICSR 13025, ICSR 13031, ICSR 13042, ICSR 13043, ICSR 13046 and ICSR 29 (Restorers, R lines and high yielding) differed in levels of resistance against sorghum shoot fly. The 48 experimental hybrids developed using these A lines and R lines were evaluated at three locations: viz., Regional Agricultural Research Station (RARS), Palem; Agricultural Research Station (ARS), Tandur and College Farm, Rajendranagar. Four standard checks were used in the investigation, and out of the four checks, two (CSV 41 and CSH 16) were used for yield analysis and two (IS 18551 as resistant and Swarna as susceptible) for shoot fly screening. In yield analysis experiment, each plot consisted of 2 rows of 4 metres each, with an inter row spacing of 45 cm and an intra row spacing of 10 cm. Normal recommended cultural practices were followed during the evaluation to raise a successful crop for better phenotypic expression of characters. In each location, five competitive plants were randomly selected from each plot for recording observations on days to 50 % flowering, days to maturity, plant height, 100 grain weight (g), grain yield per plant (g), grain yield per plot (kg), fodder yield per plant (g) and fodder yield per plot (kg). Days to 50 % flowering and days to maturity were recorded on a plot basis. In the shoot fly screening experiment, all the protection measures were avoided. Data from all the component characters associated with shoot fly resistance, such as seedling vigour, seedling glossiness, number of eggs per plant (14 DAE), trichome density on upper and lower leaf surfaces, and deadhearts per cent (21 DAE and 28 DAE) were collected from each genotype. All the data from both experiments was analyzed using windostat software (version 9.1) from indostat services at the University Computer Centre, Rajendranagar, Hyderabad. In addition to the field screening of genotypes for shoot fly resistance, a molecular screening experiment was carried out using 20 reported markers linked to shoot fly resistance to check whether the markers so far reported to be linked to shoot fly resistance can be used for differentiating the resistance and susceptibility among the parental genotypes (six lines and eight testers) used in the present study. The results from the investigation revealed that good combiners for grain yield per plant need to be desirable combiners for lower shoot fly deadhearts per cent and vice versa. The general combining ability of parents for grain yield per plant and shoot fly deadhearts per cent (28 DAE) showed that three parents involving one line and two testers viz., ICSA 433, ICSR 13009 and ICSR 13025, respectively, were found to be good general combiners for both grain yield per plant as well as lower shoot fly deadhearts per cent. Most of the good specific combiners for grain yield per plant were not desirable combiners for deadhearts per cent and vice versa. About 8 hybrids viz., ICSA 419 × ICSR 13043 (2.419 and -8.108), ICSA 427 × ICSR 13004 (33.394 and - 6.398), ICSA 427 × ICSR 13031(2.625 and -4.226), ICSA 433 × ICSR 13043 (30.482 and -5.741), ICSA 29004 × ICSR 13025 (14.130 and -4.027) and ICSA 29004 × ICSR 13046 (2.536 and -10.272) were found to be the best specific combiners for both grain yield per plant and lower shoot fly deadhearts per cent. It was found from the investigation that hybrids with high grain yield per plant need not to be with low deadhearts per cent score and vice versa. About five hybrids (displayed in the order of merit), viz., ICSA 435 × ICSR 13042 (95.285 g), ICSA 427 × ICSR 13031 (92.868 g), ICSA 419 × ICSR 13042 (84.910 g), ICSA 435 × ICSR 13031 (84.452 g) and ICSA 418 × ICSR 13009 (83.165 g) recorded high grain yield per plant as well as resistance (damage score of 3.0) against sorghum shoot fly whereas the high yielding hybrid viz., ICSA 427 × ICSR 13046 (85.107), was susceptible to shoot fly damage with high per cent of deadhearts (damage score of 7.0). Even the resistant hybrids (damage score of 3.0) viz., ICSA 419 × ICSR 13009, ICSA 427 × ICSR 13009, ICSA 433 × ICSR 13004, ICSA 433 × ICSR 13025 and ICSA 433 × ICSR 13043 were found to be low yielders across environments. Therefore, it was suggested from the present investigation that hybrids viz., ICSA 435 × ICSR 13042, ICSA 427 × ICSR 13031, ICSA 419 × ICSR 13042, ICSA 435 × ICSR 13031 and ICSA 418 × ICSR 13009 had both high yielding and shoot fly resistance characteristics and could be commercially exploited after sufficient testing. The stability parameters for component traits revealed that as many as 15 and 11 genotypes turned out to be stable for days to 50 % flowering and days to maturity, respectively, with lower means than parents and hybrids. Similarly, for plant height 12, for 100 Grain weight 11, for grain yield per plot 14, for grain yield per plant 23, for fodder yield per plot 15 and for fodder yield per plant 23, were found to be stable, i.e. they had non-significant bi and S2 di values. Female ICSA 427 and ICSA 433 recorded high grain yield per plant with better gca effects and stability for grain yield per plant and yield contributing characters. The male parent, 13031 had high grain yield along with good general combining ability and stability of performance for grain yield per plant. Three hybrids, viz., ICSA 418 × ICSR 13025, ICSA 29004 × ICSR 29 and ICSA 419 × ICSR 29 had high mean performance with average stability, high standard heterosis performance (over CSV 41 or CSH 16 or both) and desirable sca effects for grain yield and some of its component traits. Most of the hybrids recorded high grain yield per plant however, the stability performance of those hybrids was not satisfactory. Interestingly, from the entire investigation, three hybrids viz., ICSA 418 × ICSR 13025 (112.883 g), ICSA 419 × ICSR 29 (106.082 g) and ICSA 29004 × ICSR 29 (93.710 g) were found to be highly stable grain yielders. However, they showed moderate resistance against sorghum shoot fly. Therefore, these hybrids would be used for further screening of different locations. From the molecular screening of parents, it was found that among the 20 SSR markers used; only one marker viz., Xnhsbm 1011 showed differentiation of resistance for sorghum shoot fly among the parental genotypes screened. The marker was polymorphic between the lines and testers (showing a difference in banding pattern). Morphological screening studies revealed that, the performance against shoot fly was different among the parental genotypes. Lines were found to be moderately susceptible to susceptible against shoot fly at phenotypic level, whereas all eight testers were moderately resistant against shoot fly. These parents could be differentiated by this marker (Xnhsbm 1011) which showed an allele size of 150 bp in all the lines (moderately susceptible) and 160 bp in all the testers (moderately resistant). From the investigation, it can be concluded that both additive and non-additive gene effects are important, with a predominance of non-additive gene effects in governing the traits associated with yield and shoot fly resistance in sorghum. Crossing between the resistant or moderately resistant lines endowed with different resistant mechanisms is likely to produce stable lines with desirable traits. Hybrids identified in the present investigation, viz., ICSA 435 × ICSR 13042, ICSA 427 × ICSR 13031, ICSA 419 × ICSR 13042, ICSA 435 × ICSR 13031 and ICSA 418 × ICSR 13009, having superior grain yield with resistance against sorghum shoot fly, can be exploited after sufficient testing under AICRP trials.
  • Thumbnail Image
    ThesisItemOpen Access
    A STUDY ON ALLELIC RELATIONSHIP AND IDENTIFICATION OF SNP MARKERS LINKED TO FUSARIUM WILT RESISTANCE GENES IN CASTOR (Ricinus communis L.)
    (PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-01-07) MOHAN RAO, M. D.; SUJATHA, M
    Castor is an important non-edible oilseed crop having multifarious industrial applications. Its production is hampered by several biotic stresses among which wilt disease caused by Fusarium oxysporum f.sp. ricini is a major one. Being a soil borne disease, management of wilt is difficult by chemical control. Utilization of available wilt resistance sources in developing resistant varieties and hybrids remains the only viable option for management of wilt problem in castor. Though several wilt resistant lines have been identified, the genetics of resistance in those lines are not known. This study was undertaken to decipher the inheritance patterns of wilt resistance genes in a set of resistant lines, understand the allelic relationship among the resistance genes and identify markers linked to wilt resistance genes in different resistance sources. In order to study the inheritance pattern of wilt resistance in a set of nine resistant lines viz., 48-1, AP-48, AP-56, AP-70, AP-111, AP-125, AP-127, AP-156 and AP-163, F1, F2 and BC1F1 populations were generated by crossing the resistant lines with the susceptible line JI-35. The parents, F1s and segregating populations were screened in the wilt sick plot. Screening results indicated that wilt resistance was controlled by single recessive gene in 48-1 and AP-156; while it was controlled by single dominant gene in AP-56, AP-111 and AP-125; two recessive genes with complementary interaction controlled wilt resistance in AP-48, AP-163 and AP-70; and two dominant complementary genes controlled wilt resistance in AP-127. The inheritance patterns of resistance in different sources would help in devising the breeding strategies to incorporate the resistance into breeding lines of castor. The allelism test was carried out to study the allelic relationship between wilt resistance genes from six different resistant lines viz., 48-1, AP-48, AP-56, AP-111, AP 125 and AP-156. The F1s and F2 populations of six resistant × resistant crosses were screened in the wilt sick plot. Allelism test results revealed that the recessive gene in 48-1 and AP-156 were either allelic or tightly linked and were allelic to one of the two recessive genes in AP-48. The dominant genes in AP-56 and AP-111 were either allelic or tightly linked while the dominant gene in AP-125 was non-allelic to the dominant gene in AP-56 and AP-111. As the wilt resistance in castor is predominantly controlled by major genes, the resistance is prone for breakdown. The diverse resistant sources characterized in this study can be utilized in the breeding programmes to diversify the resistance genes so that pathogen evolution may be slowed down. Durable resistance in the cultivars can be achieved by pyramiding multiple resistance genes. In an attempt to validate a set of SNP loci putatively associated with wilt resistance identified through earlier QTL and association mapping studies, the SNPs were converted into KASP assays and subsequently used to genotype six F2 and three BC1F1 populations segregating for wilt resistance. The SNP loci flanking the QTL linked to wilt resistance Rc_28694-84511 (chromosome-7) co-segregated with wilt resistance in the F2 population of 48-1 × JI-35 and predicted the resistance and susceptible phenotypes with 91.7% accuracy. The SNP marker Rc_29706-482910, which is located nearer to Rc_28694-84511, predicted the resistant and susceptible phenotypes of (AP-156 × JI-35) F2 individuals with 92.2% accuracy. The same marker predicted the resistant phenotype in the segregating populations generated using AP-48 and AP-163 with 91.9 to 93.9% accuracy. Thus, the same region was implicated for wilt resistance in four resistant carrying recessive genes for resistance. The SNP marker Rc_29609-103709 on chromosome-8 predicted the resistant and susceptible phenotypes of individuals in segregating population generated using AP-56 and AP-111 (both carrying dominant genes for resistance) with 82.5 to 89.8% accuracy. Thus, this study validated the presence of two major wilt resistance gene clusters on chromosome-7 and chromosome-8, which can be further explored through fine mapping and map-based cloning. The markers linked to resistance genes would help integrating MAS in wilt resistance breeding. Towards development of near isogenic lines (NILs) in the background of the susceptible line JI-35, three backcross populations viz., [(JI-35 × AP-42) × JI-35] BC3F1, [(JI-35 × AP-156) × JI-35] BC2F1 and [(JI-35 × 48-1) × JI-35] BC1F1 were generated during the course of this study. Once developed, the NILs will be useful resources for genetic, molecular and pathological studies on Fusarium wilt in castor
  • Thumbnail Image
    ThesisItemOpen Access
    A STUDY ON ALLELIC RELATIONSHIP AND IDENTIFICATION OF SNP MARKERS LINKED TO FUSARIUM WILT RESISTANCE GENES IN CASTOR (Ricinus communis L.)
    (PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY, 2022-01-07) MOHAN RAO, M; SUJATHA, M
    Castor is an important non-edible oilseed crop having multifarious industrial applications. Its production is hampered by several biotic stresses among which wilt disease caused by Fusarium oxysporum f.sp. ricini is a major one. Being a soil borne disease, management of wilt is difficult by chemical control. Utilization of available wilt resistance sources in developing resistant varieties and hybrids remains the only viable option for management of wilt problem in castor. Though several wilt resistant lines have been identified, the genetics of resistance in those lines are not known. This study was undertaken to decipher the inheritance patterns of wilt resistance genes in a set of resistant lines, understand the allelic relationship among the resistance genes and identify markers linked to wilt resistance genes in different resistance sources. In order to study the inheritance pattern of wilt resistance in a set of nine resistant lines viz., 48-1, AP-48, AP-56, AP-70, AP-111, AP-125, AP-127, AP-156 and AP-163, F1, F2 and BC1F1 populations were generated by crossing the resistant lines with the susceptible line JI-35. The parents, F1s and segregating populations were screened in the wilt sick plot. Screening results indicated that wilt resistance was controlled by single recessive gene in 48-1 and AP-156; while it was controlled by single dominant gene in AP-56, AP-111 and AP-125; two recessive genes with complementary interaction controlled wilt resistance in AP-48, AP-163 and AP-70; and two dominant complementary genes controlled wilt resistance in AP-127. The inheritance patterns of resistance in different sources would help in devising the breeding strategies to incorporate the resistance into breeding lines of castor. The allelism test was carried out to study the allelic relationship between wilt resistance genes from six different resistant lines viz., 48-1, AP-48, AP-56, AP-111, AP 125 and AP-156. The F1s and F2 populations of six resistant × resistant crosses were screened in the wilt sick plot. Allelism test results revealed that the recessive gene in 48-1 and AP-156 were either allelic or tightly linked and were allelic to one of the two recessive genes in AP-48. The dominant genes in AP-56 and AP-111 were either allelic or tightly linked while the dominant gene in AP-125 was non-allelic to the dominant gene in AP-56 and AP-111. As the wilt resistance in castor is predominantly controlled by major genes, the resistance is prone for breakdown. The diverse resistant sources characterized in this study can be utilized in the breeding programmes to diversify the resistance genes so that pathogen evolution may be slowed down. Durable resistance in the cultivars can be achieved by pyramiding multiple resistance genes. In an attempt to validate a set of SNP loci putatively associated with wilt resistance identified through earlier QTL and association mapping studies, the SNPs were converted into KASP assays and subsequently used to genotype six F2 and three BC1F1 populations segregating for wilt resistance. The SNP loci flanking the QTL linked to wilt resistance Rc_28694-84511 (chromosome-7) co-segregated with wilt resistance in the F2 population of 48-1 × JI-35 and predicted the resistance and susceptible phenotypes with 91.7% accuracy. The SNP marker Rc_29706-482910, which is located nearer to Rc_28694-84511, predicted the resistant and susceptible phenotypes of (AP-156 × JI-35) F2 individuals with 92.2% accuracy. The same marker predicted the resistant phenotype in the segregating populations generated using AP-48 and AP-163 with 91.9 to 93.9% accuracy. Thus, the same region was implicated for wilt resistance in four resistant carrying recessive genes for resistance. The SNP marker Rc_29609-103709 on chromosome-8 predicted the resistant and susceptible phenotypes of individuals in segregating population generated using AP-56 and AP-111 (both carrying dominant genes for resistance) with 82.5 to 89.8% accuracy. Thus, this study validated the presence of two major wilt resistance gene clusters on chromosome-7 and chromosome-8, which can be further explored through fine mapping and map-based cloning. The markers linked to resistance genes would help integrating MAS in wilt resistance breeding. Towards development of near isogenic lines (NILs) in the background of the susceptible line JI-35, three backcross populations viz., [(JI-35 × AP-42) × JI-35] BC3F1, [(JI-35 × AP-156) × JI-35] BC2F1 and [(JI-35 × 48-1) × JI-35] BC1F1 were generated during the course of this study. Once developed, the NILs will be useful resources for genetic, molecular and pathological studies on Fusarium wilt in castor