ThesisItem Open AccessMOLECULAR TAGGING OF YELLOW MOSAIC VIRUS (YMV) RESISTANCE IN MUNGBEAN [Vigna radiata (L.) Wilczek](ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR, 2019) VENKATA LAKSHMI PRASANNA, B; SRIVIDHYA, AThe Yellow Mosaic Disease (YMD) in mungbean is reported to be the most devastating viral disease, caused by yellow mosaic virus (YMV) which is transmitted by whitefly (Bemisia tabaci). It causes considerable yield reduction even upto 85-100 %, depending on the stage of crop it affected. Development of resistant varieties is the most desired approach to alleviate the problem. However, the inheritance pattern of disease is not yet properly understood and also scope for the artificial screening of virus resistance is meager. Thus, posing the big challenge in selecting stabilized breeding line(s) or identification of resistance genotype(s). It is already proved that marker assisted selection can support the conventional approach with precision in every selection cycle. With this premise the present study was done to identify the molecular markers linked to YMV tolerance in mungbean employing bulk segregant analysis (BSA) and further validation of these markers through marker-trait co-segregation study. The parental polymorphic survey between EC 396117 (YMV resistant parent) and TM 96-2 (YMV susceptible parent) was done with 81 SSR and ESTSSR markers. Of these, only 6 primers showed the polymorphic alleles with 7.4 % polymorphism between parents. Phenotyping of F2:3 population for YMV tolerance/susceptibility was done during the summer, 2018 and the contrasting progeny for the disease tolerance was identified. Ten resistant and ten susceptible F2 plants were selected for which the bulk segregant analysis (BSA) was performed with the polymorphic primers. Genotyping of bulks resulted in heterozygous allelic pattern for all the primers under study. This can be attributed to the occurrence of heterozygous nature of few selected F2 plants at these loci, the variable gene action (recessive/ xv dominance) or might be due to the selection of disease escapes that constitute the resistant bulk, thus the possibility of occurrence of heterozygotes in the panel. Hence, further validation of these markers was done through marker-trait cosegregation study. A total of 135 F3 progenies were screened for YMV tolerance/ susceptibility during summer, 2019. Chi-square analysis of the disease score revealed 9 resistant :7 susceptible ratio, indicating complementary gene action. The polymorphic markers were validated in the F3 progenies that are derived from the respective F2 plants, involved in the BSA. From the marker-trait association study it is observed that, the primers CEDG 245 and CEDG305 have showed 70 % tolerant alleles in BYT. Nucleotide BLAST of the CEDG305 primer against sequence databases targeted a protein coding gene, LOC106765125 (Synaptotagmin-2-like) that has proved to be involved in cell to cell movement of diverse family of plant viruses including Begomoviruses. Hence, characterization of the identified gene through sequencing between the parents may further elucidate the responsible variations for YMV tolerance, possibly due to hindrance of cell to cell movement of YMV (Begomovirus) particles. From the study, it can be suggested that the marker CEDG305 has the potential to use in identification of YMV resistant genotypes and the parent EC396117 can be successfully used in marker assisted breeding programmes as donor along with the identified marker source, to develop YMV tolerant varieties besides further confirmation of marker loci with the development of recombinant inbred lines/near isogenic lines. In conclusion, the bulk segregant analysis and there by the marker-trait validation study proved the possibility of identification of marker resource that linked with desirable trait at rapid rate by avoiding the expensive genotyping costs that associated with total population analysis, which usually followed in mapping approaches. ThesisItem Open AccessMARKER ASSISTED SELECTION FOR BACTERIAL LEAF BLIGHT RESISTANCE IN RICE (Oryza sativa L.)(Acharya N G Ranga Agricultural University, Guntur, 2019) VANI, M; ESWARA REDDY, N.PNellore Mahsuri (NLR34449) is a local popular rice variety, and is mostly adopted by many of the farmers due to its fine grain nature, short duration, non-lodging, saline resistance with high yielding nature and suitability for cultivation in any season. This variety is also resistant to one of the major diseases of rice, leaf blast but susceptible to bacterial leaf blight (BLB), another most devastating disease in rice growing areas. To combat the problem, development of varieties carrying resistant genes has been considered to be the most effective way to control the BLB disease and is economical and environmentally safe option for management of BLB. In the present investigation an attempt was made to improve NLR34449 for BLB resistance by introgressing three major resistant genes viz. Xa21, xa13 and xa5 from RPBio226 (Improved Samba Mashuri) using marker assisted selection. When phenotypic screening of NLR34449 and RPBio226 was done with artificial inoculation of pathogen, it revealed that NLR34449 was found to be susceptible as it showed lesion length of 5.0 -7.5 cm at 7 days after inoculation when compared to RPBio226, that showed hypersensitive reaction to the pathogen. Similarly, the genotyping of these two varieties using three gene specific markers namely pTA248, xa13prom, xa5FS, linked to the BLB resistance genes viz., Xa21, xa13 and xa5, respectively revealed that the NLR34449 is lacking these broad spectrum genes. The two parents were crossed to produce F1. True F1s were confirmed using gene specific markers xa13prom (xa13), pTA248 (Xa21), xa5FS (xa5). BLB gene positive F1s were allowed to undergo self pollination to produce F2 seed. Initially 90 F2 plants were screened phenotypically by using artificial clip inoculation method. A total of 22 plants that fell in the resistant and moderately resistant classes with lesion length of 0.6 – 4.3cm were selected and subjected for genotypic screening by employing three gene specific markers namely pTA248, xa13prom, xa5FS, linked to the BLB resistant genes viz., Xa21, xa13 and xa5, respectively. Out of 22 plants, 3 were found to be positive for xa13 and Xa21 and 4 plants were positive for xa5 gene, whereas, two plants each were double positive for the gene combinations Xa21 + xa13, xa13 + xa5 and for Xa21 + xa5. Only, one F2 plant possessed all three genes in homozygous condition i.e. of RPBio226 alleles. the plants that consisting of the combination of xa13 and Xa21, the broad spectrum genes were artificially re-inoculated with the increased dose of inoculum (10-8 cfu/ml) to confirm their resistance level to the pathogen. At higher concentration also the gene pyramided plants showed very less disease reaction i.e. ranged from hypersensitivity reaction to 2.7cm. Thus, they were confirmed as BLB resistant plants. In conclusion, in the present investigation NLR34449 variety, which is high yielding, fine grain, and susceptible to BLB disease has been pyramided with three BLB genes from RPBio226. Hence, the potency of early generation selection method can be once again highlighted from the study in pyramiding of two or more genes at F2 generation itself which might not be possible with conventional approach alone. Hence, identification of tightly linked markers for the desirable traits needs to be hastened up for the varietal development wherein it is achievable at faster pace with the knowledge available in the sequence based databases. ThesisItem Open AccessIDENTIFICATION OF MOLECULAR MARKERS LINKED TO RUST RESISTANCE IN GROUNDNUT (Arachis hypogaea L.)(Acharya N G Ranga Agricultural University, Guntur, 2019) SRI VIDYA, G.K; AMARAVATHI, YCultivated groundnut is an allotetraploid which is mainly grown in tropical and subtropical countries. Rust (Puccinia arachidis Speg.) is one of the major foliar fungal diseases in groundnut which causes significant yield loss. With this background, the present investigation was aimed for identification of molecular markers linked to rust resistance in groundnut (Arachis hypogaea L.). The F2 mapping population derived from the cross between TMV 2 (Rust susceptible) and ALG-06-320 (Rust resistant), was generated and the inheritance pattern of rust was analyzed. In this cross, rust resistance governed by homozygous recessive genes in duplicate dominant gene action (15: 1) was reported. The parental polymorphism survey was carried out with 100 SSR. Out of 100 SSR markers, SEQ16C6, GM 1733, SEQ9H08, TC2A02, PM 384, PM 418 and SEQ15C10 were polymorphic between the parents. Very low polymorphism of only 7% was reported. Bulk Segregant Analysis of seven polymorphic SSR markers resulted in identification two SSR markers GM 1733 and SEQ16C6 co-segregated with the respective parental genotypes.These markers can be considered as candidate markers for molecular breeding. The F2 population was genotyped with ten SNP markers snpAH0015, snpAH0017, snpAH0018, snpAH0021, snpAH0026, snpAH0004, snpAH0005, snpAH0010, snpAH0011 and snpAH0002. All the ten SNP markers were monomorphic and except for snpAH0005 which carried susceptible allele in both the parental lines and snpAH0002 expressed only in few F2 lines but not in parents. Surprisingly, the counterpart alleles (susceptible/resistant) not scored in the parental lines was appeared in 25% of the population. The whole genome search for resistance genes resulted in 1434 RGAs localized over the 20 chromosomes of cultivated groundnut. These RGAs were analyzed for the SSRs and 236 RGAs were found to enclose the SSRs within them. A total of 11 SSR markers employed in parental polymorphism survey were found to be linked with RGAs in cultivated groundnut. These markers can be employed for development of durable broad spectrum resistance in groundnut for rust disease. ThesisItem Open AccessSTUDIES ON THE TRANSFERABILITY AND EFFICIENCY OF DIFFERENT DNA MARKER SYSTEMS FROM OTHER VIGNA SPECIES IN MUNG BEAN (Vigna radiata (L.) Wilczek)(Acharya N G Ranga Agricultural University, Guntur, 2019) MANORAMA, KESINENI; RAMANA, J.V.The present investigation was carried out at MBB lab, Advanced Post Graduate Centre, Lam, Guntur, Andhra Pradesh. Mung bean (Vigna radiata (L.) Wilczek) is a self-pollinated crop. It is a diploid grain legume (2n=22) with a genome size of 579 Mbp. It is a good substitute for meat in most Asian diet and a significant component of various cropping system. To characterize 38 genotypes of mung bean using SSR, RAPD and ISSR markers to study the transferability, efficiency and polymorphism. The study was to examine the transferability of SSR, RAPD and ISSR markers in mung bean from related Vigna spp and study their validity in efficiency analysis. Sixty four markers were used which includes forty six SSR, nine RAPD and nine ISSR. Forty seven markers (thirty two markers of SSR, nine primers of RAPD and six primer of ISSR) out of the sixty four markers were amplified from other Vigna species and transferable to mung bean. Thirty two primers of SSRs which were transferred to mung bean were from other Vigna species. Adzukibean, Blackgram, Chickpea, Cowpea and Rice bean showed 89, 100, 40, 70 and 67 per cent transferability, respectively. The range of transferability across Vigna species was 67-100%. The range of transferability across mung bean genotypes was 7- 100%. Nine primers of RAPD which were transferred to mung bean were from other Vigna species have shown 100% transferability to mung bean. Nine RAPD markers were transferable which yielded fifty nine alleles with an average of 6.6 alleles per locus. The transferability range across mung bean genotypes was 73.7 – 100%. Six primers of ISSR which were transferred to mung bean were from other Vigna species have shown the transferability range 50- 100%. The range of transferability across mung bean genotypes was 92 - 100%. xiv Expected heterozygosity of SSR, RAPD and ISSR marker ranges from 0.05- 0.5, 0.491 and 0.145-0.499 respectively. Average heterozygosity of SSR, RAPD and ISSR is 0.256, 0.113 and 0.132.respectively. Average EMR ratio for SSR, RAPD and ISSR markers 2.03, 4.676 and 2.57 respectively. Average marker index value for SSR, RAPD and ISSR was 0.57, 1.73 and 0.834 respectively. CEDG103, CEDG022 and CaGM01514 markers were mostly monomorphic among all the mung bean genotypes under study. Most markers were polymorphic which was less than 5 i.e. least informative. OPN 9 primer of blackgram showed unique allele at 900 bp in Pusa Baisakhi. Jaccard’s similarity coefficient ranged for SSR markers from 0.61 to 0.88. Highest JSC value in cluster I and lowest JSC value in cluster IV. Jaccard’s similarity coefficient for RAPD ranged from 0.6 - 1. Highest JSC value in cluster I and lowest JSC value in cluster IV. Jaccard’s similarity coefficient for ISSR ranged from 0.56 - 1. Highest JSC value in cluster I and lowest JSC value in cluster III. In conclusion, RAPD and ISSR were multi locus marker systems expected to produce higher EMR and MI values were efficient than single locus (SSR) marker systems. RAPD and ISSR were good in the detection of polymorphism and also efficient marker systems. Similarity coefficients were same for multi locus marker systems (ISSR and RAPD) which is low than single locus marker systems (SSR). Finally they indicated narrow genetic base of tested green gram landraces. Breeding between the genotypes (intraspecific) in mung bean shows less variation. So, better to go for interspecific breeding to develop variation. ThesisItem Open AccessMOLECULAR DIVERSITY STUDIES IN SESAME (Sesamum indicum L.)(Acharya N G Ranga Agricultural University, Guntur, 2019) PAVANI, KODURU; LAL AHAMED, MThe present study was carried out with thirty genotypes of sesame for characterization based on 20 DUS characteristics of PPV&FRA (Agricultural Research Station, Yelamanchili, Visakhapatnam District of Andhra Pradesh) and molecular diversity analysis using SSR markers (Advanced Post Graduate Centre, Lam , Guntur). The DUS characters, branching pattern (basal), leaf size (large), leaf serration (serrate), flower petal colour (light purple), flower petal hairiness (dense), locule number/capsule (four), capsule shape (broad oblong), capsule number/leaf axil (one) and capsule arrangement (alternate) showed no variability. The characters, days to 50% flowering, plant height (cm), plant branching, stem hairiness, leaf lobes, capsule hairiness, capsule length (cm), days to maturity, seed coat colour, 1000 seed weight (g) and oil content (%) showed variability phenotypically and are considered for the identification and characterization of genotypes. The cluster analysis based on eleven variable DUS characteristics grouped the genotypes into 5 clusters at 85 % similarity. The similarity level (85 to 100 %) in the clustering pattern clearly indicated the presence of sufficient variability for few traits among the genotypes for differentiation. The molecular characterization with 50 SSR primers revealed the use of 45 primers for characterization as they produced clear banding pattern. Only seven primers showed polymorphism and total number of bands produced were 191 with 7 primers. The number of alleles per locus was varied from 2 to 6 with an average of 3.57 alleles per locus. The size of the scoring bands ranged from 120 to 300 bp. PIC values of xiii primers ranged from 0.28 to 0.80 with an average value of 0.47. The Number of effective alleles (Ne) ranged from 1.38 to 4.86 with an average of 2.49. Average expected heterozygosity (He) values ranged from 0.27 to 0.79 with an average of 0.53. The Average Shannon’s diversity index (Ic) was 0.95 with the range of 0.40 to 1.65. These allele diversity values indicated the high level of informativeness of these markers in the present material. The dendrogram prepared from the UPGMA grouped the genotypes into 4 clusters and a clade at similarity coefficient value of 0.85. The similarity coefficient values range was 0 to 1. The cluster-I had 12 genotypes while the clusters-II, III and IV had five, seven and five genotypes, respectively, indicating the existence of sufficient variability in the lines studied. The clade had one genotype (MLTS-1). Further, the similarity coefficient values indicated the very close relatedness among the genotypes of GOURI and MADHAVI; GOURI and YLM-164; MADHAVI and YLM-164; YLM149 and YLM-150; MLTS-7 and YLM-148; MLTS-8 and TKG-22. The similarity values were minimum between the genotypes of the clusters II and IV indicating their exploitation. The released varieties were grouped into the cluster I while the MLTS genotypes were grouped into the cluster IV indicating their high level of genetic similarity among the genotypes present in these clusters. Thus, the preliminary study on DUS characterization and molecular diversity in sesame genotypes of ARS, Yelamanchili revealed the presence of sufficient variability at both morphological and molecular levels. The comparative study involving both morphological and molecular data indicated that there is no correlation among the genotypes grouped in clusters. This study also reported the potentiality of SSR markers for studying the genetic relatedness among the genotypes of sesame. ThesisItem Open AccessIDENTIFICATION OF DIFFERENTIALLY EXPRESSED TRANSCRIPTS IN GROUNDNUT CHALLENGED WITH Sclerotium rolfsii Sacc. CAUSING STEM ROT(Acharya N.G. Ranga Agricultural University, 2018) RAJASEKHAR, SRUNGARAPU; AMARAVATHI, YStem rot mainly a soil-borne disease caused by Sclerotium rolfsii, is one of the major constraints in groundnut production as it severely affects the yield and quality of the produce. The present investigation was aimed for histopathological, biochemical and identification of differentially expressed transcripts in response to stem rot caused by Sclerotium rolfsii in groundnut. A total of fifteen genotypes viz., ICGV 91114, ICGV 86590, ICGV 86031, ICGV 87160, ICGV 87157, ICGS 76, ICGS 44, ICGV 07132, ICGV 07072, CS19, Dharani, Kadiri 6, Rohini, TCGS 1157 and Narayani were selected and screened for stem rot resistance or tolerance in pot culture under artificial conditions. Among these fifteen genotypes, ICGV 86590 found to be highly tolerant as it has not shown any wilting symptoms even fifteen days after inoculation with S. rolfsii and in contrast, Narayani found to be highly susceptible with complete wilting and subsequent death of the plant. The pot culture experiments were carried out in the glass house of Regional Agricultural Research Station (RARS) and Molecular analysis at Genomics lab, Institute of Frontier Technology (IFT), RARS, Tirupati. The contrasting genotypes for stem rot viz., ICGV 86590 (tolerant) and Narayani xv (susceptible) were further analyzed for Scanning Electron Microscopy, Biochemical and Molecular parameters at 24 hrs interval upto 4 days. Scanning Electron Microscopy studies showed presence of distorted xylem vessels with fungal mycelial growth in susceptible genotype, Narayani at 72 HAI whereas in tolerant genotype, ICGV 86590 even at 72 HAI no mycelial growth were observed in xylem vessels. The accumulation of total phenol content was relatively increased by 2 folds in ICGV86950 at 96 hours after inoculation when compared to susceptible genotype Narayani. The elevated levels of total phenols play an important role in the resistance mechanism against infection with S.rolfsii in tolerant groundnut genotype. Chitinase activity was significantly increased 6 times more in ICGV86590 at 96 hrs after challenged with S. rolfsii whereas in Narayani it was almost constant throughout the sampling time in comparison with their respective controls. Peroxidase activity was induced as an early response to counter the fungal pathogen attack and the infected tissue showed a higher activity of the enzyme at 96 hrs after inoculation in tolerant genotype (1.87 min/gm/fresh weight) when compared with susceptible genotype (0.42 min/gm/fresh weight). β-1, 3-Glucanase activity was increased continuously at all sampling intervals in both stem rot tolerant and susceptible genotypes in comparison with their respective controls and was maximum in tolerant genotype ICGV 86590 at 96 hrs after S. rolfsii inoculation. Polyphenol oxidase increased significantly upto 72 hrs after inoculation in ICGV 86590 and slightly decreased at 96 hrs whereas in susceptible genotype the polyphenol activity was slight increased throughout sampling period. To unravel the molecular mechanisms conditioning stem rot tolerance, transcriptome was analyzed in groundnut subjected to S. rolfsii (0 to 96 hrs after inoculation). To identify differentially expressed transcripts, cDNARAPD analysis was carried out using total RNA collected from stem portion near collar region from both unchallenged (control) and challenged constrasting genotypes at 24 hrs interval upto 4 days. To identify differentially expressed transcripts the transcriptome was analyzed by cDNA-RAPD profiles in tolerant and susceptible groundnut genotypes subjected to S. rolfsii. A total of 3485 Transcript Derived Fragments (TDFs) were scored. Out of which 2137 TDFs were differentially expressed in both resistant and susceptible genotypes challenged with S. rolfsii at 24 hrs interval upto 4 days. Among the 2137 differentially expressed transcripts, 1471 transcripts exhibited qualitative difference and 666 transcripts displayed xvi quantitative differences in banding pattern of cDNA-RAPD profiles among the two groundnut genotypes. The transcriptome data analyzed by cDNA-RAPD profiles can serve as a valuable resource for gene discovery and the differentially expressed genes can be cloned and further sequenced to reveal the function. Thus the identified transcripts/genes can also be converted to functional markers and can be used in marker assisted selection for stem rot resistance breeding. ThesisItem Open AccessMARKER ASSISTED INTROGRESSION OF BACTERIAL LEAF BLIGHT RESISTANCE GENES INTO AN ELITE RICE VARIETY, NELLORE MASHURI(Acharya N.G. Ranga Agricultural University, 2018) DIVYA, PAMMINA; ESWARA REDDY, N.P.Nellore Mahsuri (NLR34449) is a popular rice variety, and mostly adopted by many of the farmers by virtue of its fine grain appearance, short duration, non-lodging and high yielding characters. This variety is resistant to leaf blast but susceptible to bacterial leaf blight (BLB), the second most devastating disease in rice growing areas. The development of resistant varieties has been the most effective and economical strategy to control this disease. In the present investigation, an attempt was made to improve the NLR34449 for BLB resistance by introgressing three major resistant genes i.e., xa13, Xa21and xa5 from RPBio226 (improved samba Mahsuri) using marker-assisted backcross breeding. Phenotype screening of Nellore Mahsuri (NLR34449) and RPBio226 revealed that NLR34449 is found to be susceptible as it showed more lesion length in comparison to the RPBio226. Similarly, the genotyping of these two varieties using three gene specific markers namely pTA248, xa13 prom, xa5FS, linked to the BLB resistance genes viz., Xa21, xa13 and xa5, respectively revealed that the NLR34449 is devoid of these broad spectrum genes. Further, screening of the parents with 120 markers showed 30 polymorphic markers, which covered almost all rice chromosomes evenly. These polymorphic markers were used for background selection in BC1F1. The two parents were crossed to produce F1. True F1s were confirmed using gene-specific markers xa13prom (xa13), pTA248 (Xa21), xa5FS (xa5) and backcrossed with NLR34449 to generate 200 BC1F1. In all, 126 phenotypically superior BC1F1 plants were selected from the 200 BC1F1s plants, based xvi on the plant type similar to NLR34449 and further characterized for BLB resistance employing molecular and phenotypic studies The BC1F1 plants were screened with BLB gene-specific markers and 30 polymorphic markers for both foreground and background selection, respectively. Out of 126 BC1F1 plants selected, 21 were found to be positive for xa13, 18 were positive for Xa21, 32 were positive for xa5 gene, whereas, 16 were double positive for both Xa21 and xa13, 13 were double positive for both Xa21 and xa5, 15 were double positive for both xa13 and xa5. Interestingly, 9 BC1F1 plants with triple positive for Xa21, xa13 and xa5 genes were identified from foreground screening. Further 9 selected BC1F1 plants were subjected to the recombinant selection employing the closely located targeted 3 BLB genes to minimize the linkage drag from RPBio226 at these loci. In background selection the selected BC1F1 (three gene pyramid) plants were screened with 30 polymorphic markers. Recovery percentage of recurrent genome was 76.7 – 83.3 % and exhibited high levels of resistance against BLB. The BLB introgressed progeny BC1F1- 9 had showed significant yield increase (31.5) over NLR34449 apart from very low disease score (0.5-lesion length). However, BC1F1- 54 (20.6g); BC1F1- 79 (22.1); and BC1F- 82 (21.7) had recorded yield levels similar to donor parent. Hence, the BC1F1 plants that are having high yield levels along with BLB tolerance and almost all recurrent parent traits would be used to progress further generations to use as straight variety. In conciusion, in the present investigation NLR34449 high yielding fine grain variety susceptible to BLB disease and has been introgressed with three BLB genes from RPbio226. ThesisItem Open AccessValidation of QTLs for Yellow Mosaic Virus Tolerance in Mungbean (Vigna radiata (L.) Wilczek)(Acharya N.G. Ranga Agricultural University, 2018) KEERTHI, ISSA; SRIVIDHYA, AGreen gram (Vigna radiata (L.) Wilczek), is one of the important pulse crops mainly grown in developing countries. However, the yield level of the crop is very low due to many biotic and abiotic factors. Among biotic factors, yellow mosaic virus (YMV), which is transmitted by white fly (Bemisia tabaci) causes significant yield losses ranging from 10-100%. With this background, the present investigation was initiated to validate the reported markers linked to the YMV resistance in a F2 segregating population. The genotypes, TM-96-2 (Trombay Mungbean), susceptible to Yellow Mosaic Virus (YMV) and EC-396117 (Exotic Collection) tolerant to YMV were chosen as parents for development of F2 population. The parental DNA was screened with 206 markers which include microsatellites (203), RAPD (2) and SCAR (1) to detect the polymorphic markers. Out of these markers, 110 were amplified and 73 markers were not amplified. Of these 110 amplified markers, only 16 primers showed polymorphism (14.5%) between the parents, and the rest of the markers were found to be monomorphic. True F1 plants were selected after confirming their heterozygosity at molecular level using polymorphic microsatellite marker, CEDG305. These F1s were selfed to produce F2 population during Rabi, 2017-2018. As many as 150 F2 individuals along with the parents were evaluated for YMV tolerance at RARS, Tirupati during Summer, 2018 under natural field conditions. The DNA has been extracted from the parents and F2 population. All the 150 F2 plants were screened with the 16 polymorphic markers. Out of these markers, only 5 showed clear scorable bands in F2 xiv population. These 5 markers were CEDG245, CEDG149, CEDG305, DMBSSR125 and CEDG228. Single marker analysis of these five markers in the F2 population using MapDisto software v.2.0 revealed a significant association of CEDG228 marker with YMV tolerance. NCBI-BLAST analysis of primer sequence of CEDG228 hit an expressed gene, LOC106773961 of the greengram genome. In conclusion, the marker, CEDG228, which has shown association with the YMV tolerance in the present investigation, has the potential to use in marker-assisted breeding of the development of YMV tolerant green gram varieties. However, further validation of this marker in a diverse set of resistant and susceptible cultivars is warranted before being used in large scale marker-assisted selection programmes. ThesisItem Open AccessMORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF COTTON (Gossypium hirsutum L.)(Acharya N.G. Ranga Agricultural University, 2018) ANJANI, ALLURI; PADMA, VThe present investigation was carried out during kharif 2017-18 at Regional Agricultural Research Station, Lam and APGC, Lam, Guntur to characterize 40 genotypes of cotton (G. hirsutum) using DUS characterstics of PPV & FRA and SSR markers and also to study the variability, heritability, genetic advance as per cent of mean, and genetic divergence of seed cotton yield per plant and yield component traits. The data were recorded on 20 descriptors viz., leaf colour, leaf hairiness, leaf appearance, gossypol glands, leaf nectaries, leaf petiole pigmentation, leaf shape, stem hairiness, stem pigmentation, bract type, petal colour, petal spot, stigma position, anther filament colouration, pollen colour, boll bearing habit, boll colour, boll shape, boll surface, prominence of boll tip and 14 quantitative characters viz., plant height (cm), days to 50 % flowering, number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight (g), seed index (g), lint index (g), ginning outturn (%), 2.5% span length (mm), uniformity ratio, micronaire value (10-6 g/inch), bundle strength (g/tex) and seed cotton yield per plant (g). The morphological descriptors indicated variability for eight characters (leaf petiole pigmentation, stem pigmentation, petal colour, stigma position, pollen colour, boll shape, boll surface, prominence of boll tip) out of twenty characters studied and these traits are helpful for the identification of the genotypes from one another and some of the characters like stem hairiness, can be exploited for breeding pest resistant genotypes. The genotypic coefficients of variation for all the characters studied were lesser than the phenotypic coefficients of variation indicating the masking effect of environment. Wide genetic variability was observed for the characters viz., plant height, number of sympodia per plant, number of bolls per plant, boll weight and seed cotton yield per plant. High heritability coupled with high genetic advance as per cent of mean was recorded for seed cotton yield per plant indicating the preponderance of additive gene action and hence further improvement may be done through simple selection procedures. The results of Mahalanobis D2 analysis indicated the presence of considerable genetic divergence among the 40 genotypes and the traits bundle strength, days to 50% flowering, number of monopodia per plant, 2.5% span length and boll weight contributed maximum towards genetic divergence. The 40 genotypes were grouped into 7 clusters using Tocher’s method indicating genetic diversity and geographical diversity were not related. The cluster I had the maximum number of genotypes while the intra-cluster distance was maximum in the cluster II. The clusters III, IV, V, VI, and VII were solitary clusters. The inter cluster distance was maximum between clusters II (SCS 1061, CCH 14-2, TSH 0533-1, RS 2767, SCS 1207, L 1008, CCH 14-1, GJHV 510, BS 26) and VI (BS 23) indicating the importance of genotypes present in these clusters in hybridization programme for the exploitation of heterosis. The cluster II recorded the highest mean values for the quality traits and seed cotton yield per plant and these genotypes can be effectively exploited in the breeding programmes. In the present study, 40 genotypes were also screened with 50 SSR primers out of which 19 showed polymorphism and the PIC values were also higher for 17 primers indicating their usefulness in characterization. The jaccard’s similarity coefficient values ranged from 0.03 to 0.80 indicating that the cultivars have a vast genetic base. The genotypes, RAH 1033 and L 788 showed least similarity coefficient value among the genotypes revealing their use in hybridization programme for generating variability and production of transgressive segregants in the future generations. The genotypes were grouped into seven clusters using UPGMA method. The cluster I had nine genotypes while the cluster III was the second largest cluster with 11 genotypes. The cluster IV was the largest with sixteen genotypes. The clusters II, V, VI and VII were solitary clusters.