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20204
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Subject: Vegetable Science × End date: 2020 × Start date: 2020 × Thesis Type: Ph.D ×
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    Molecular mapping and interspecific hybridization for hull-less seed trait in pumpkin for value addition in food processing industry
    (Punjab Agricultural University, Ludhiana-, 2020) Barinder Kaur; Dhatt, Ajmer Singh
    The present investigation entitled ‘Molecular mapping and interspecific hybridization for hull-less seed trait in pumpkin for value addition in food processing industry’ was conducted in the Department of Vegetable Science, Punjab Agricultural University, Ludhiana from 2016 to 2020. Segregating populations were developed using hulled and hull-less genotypes of Cucurbita pepo for understanding the genetics and molecular mapping of hull-less seed trait. Chi-square analysis of segregating populations revealed that single recessive gene is responsible for controlling this trait. The sequence based bulked segregant analysis of two extreme bulks (hulled and hull-less) of cross HP111 × HLP36 along with their parental lines identified one QTL on chromosome 12 (Cp4.1LG12) between 1891261 to 3863267 bp covering 1.97 Mb genomic region with 396 number of SNPs for hull-less seed trait. In interspecific hybridization, total 916 crosses between C. pepo (HLP36, HLP44, HLP53, HLP72) and C. moschata (HM1404, HM108, HM1343, HM1022, HM2211, HM6711) were attempted to transfer hull-less seed trait, however success was achieved in 5.57% crosses only. The fruit setting, number of seeds/fruit, seed germination and survival of F1 seedlings were high when C. pepo was used as female parent in cross HLP36 × HM1343 (66.67%, 15.00, 45.24% and 49.48%), followed by HLP36 × HM1022 (22.73%, 23.00, 44.35%, 47.06%) and HLP44 × HM1022 (13.79%, 12.00, 45.85%, 45.46%), respectively. However, in reciprocal crosses (C. moschata × C. pepo) success rate was very poor, which was overcome through in vitro ovule culture after 17 to 19 days of pollination in cross HM1343 × HLP53 and HM6711 × HLP72. The hybridity of putative Cucurbita interspecific hybrids was confirmed through molecular, morphological and micromorphological markers and their results were found to be highly consistent. The phenotyping of F2 populations of interspecific crosses confirmed the transfer of hull-less seed trait. Findings of the present study will facilitate in genetic dissection of candidate gene(s) and to enhance productivity, improve quality and multi-season cultivation of hull-seeded pumpkin in India.
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    Marker assisted breeding for introgression of genetic male sterile ms10 gene from hot pepper to heat tolerant bell pepper
    (Punjab Agricultural University, Ludhiana-, 2020) Menisha Rani; Jindal, Salesh Kumar
    In the present investigation, marker assisted selection (MAS) strategy was employed to introgress genetic male sterile (GMS) ms10 gene from the donor parent MS-12 (Capsicum annuum var. annuum), popular GMS line, into the genetic background of eight heat tolerant bell pepper (C. annuum var. grossum) inbreds, to develop new GMS lines in bell pepper. The chi-square test (χ2) results of six F2 and BC1F2 populations showed that the ratio well fitted to the Mendelian ratio i.e. 3:1, validated the non-discriminated segregation of the male sterility (MS) trait possessing ms10 gene. The analysis confirmed that the MS trait is inherited by a single recessive gene. Further, the recently identified molecular marker ‘AVRDC-PP12’ linked to the ms10 gene was employed to test the segregation in backcross generations of bell pepper incorporated with the ms10 gene. A total of 576 and 360 individuals in BC1F1 and BC2F1, respectively, 72 plants of each BC1 and 60 plants of each BC2 were screened (foreground selection) for the ms10 gene by using SSR marker. Among the eight backcrossed populations screened, six were showed compatibility with the ms10 gene. The results were analyzed by χ2-tests to know whether the observed number of plants in each class fitted well to the anticipated genetic ratio of 1:1. The molecular marker in each backcrossed series displayed a good fit in-to the expected ratio of Mendelian segregation i.e. 1:1 for one gene in backcross population(s), which was non-significant at a probability level of 0.05, indicating the relationship with pepper male sterility ms10 gene. Simultaneously, targeted gene positive (Ms10ms10) non-pungent (pun1) heterozygous plant(s) were identified in BC2F1 generations using BF7 and BF9-SCAR marker. A total of 27 BC2F1 Ms10ms10 plants of MSSM-2 population were segregated in a 5: 22 non-pungent to pungent ratio, and 26 Ms10ms10 plants of MSSM-3 segregated in 3 (non-pungent): 23 (pungent) ratio. The rest of the four BC2F1 populations, MSSM-1, MSSM-9, MSSM-17 and MSSM-21 have pungent heterozygous male fertile (Ms10ms10 Pun1pun1) plant. The background recovery rate of the recurrent parent phenome (RPP) in BC2F1 progeny was estimated by measuring the shift in means for horticultural traits. Based on a paired 't' test analysis, out of six, the MSSM-1 and MSSM-2 generation was shown to be non-significant for all 19 studied traits followed by MSSM-3 (18), indicating a successful recovery of the recipient genome through marker-assisted backcross breeding after successful introgression of the ms10 gene. Finally, from this work six gene positive (ms10) GMS lines namely, MSSM-1, MSSM-2, MSSM-3, MSSM-9, MSSM-17 and MSSM-21 were obtained. The newly developed GMS lines will provide great economic value for non-pungent hybrid bell pepper seed production in the near future.
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    ThesisItemOpen Access
    Imparting root knot nematode resistance through grafting in tomato (Solanum lycopersicum L.)
    (Punjab Agricultural University, Ludhiana, 2020) Sumeet Singh; Kulbir Singh
    The present investigation was conducted at Vegetable Research Farm, Department of Vegetable Science, Punjab Agricultural University, Ludhiana for “Imparting root knot nematode resistance through grafting in tomato (Solanum lycopersicum L.)” during Autumn season of 2015-2016 and 2016-17. The work plan was divided into three experiments based on different grafting methods which further divided into two different sites i.e. infested with root knot nematode and non-infested soil. Ten rootstocks with combination of two different scions (Punjab Sartaj and Punjab Ratta) were used as experiment material. For infested plots pure culture of nematodes were raised by taking galled roots of tomato plants from infested plots than galls were teased and freshly hatched second stage juveniles were raised and used for inoculums. It was observed that plant and fruit characters like plant height, fruit weight, harvest duration, marketable yield as well as total yield increased in grafted plants over nongrafted plants both in nematode free as well as Nematode infested plots. Further it was also revealed that plants grafted with Tube graft method observed highest success rate and was even responsible for earliness as well as high marketable yield in tomato plants. On evaluation of rootstocks plants grafted on EC-119197 recorded highest plant height, higher total and marketable yield, higher fruit weight and prolonged harvest duration both in Nematode infested and nematode free plots. Whereas plants grafted on rootstock PNR-7 recorded early flowering as well as early picking in infested plots. Rootstock L-097 recorded maximum fruit TSS while plants grafted on rootstock EC-119197 recorded maximum pericarp thickness. No significant effect was observed when grafted and non-grafted plants were examined for lycopene content. Overall rootstock EC-119197 can be used as a resistant rootstock against root knot nematode in addition it can fetch higher yield and better fruit quality.
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    ThesisItemOpen Access
    Identification and characterization of salt tolerant genotypes and salt tolerant gene in brinjal (Solanum melongena L.)
    (Punjab Agricultural University, Ludhiana, 2020) Talwar, Dilpreet; Kulbir Singh
    The present investigation was conducted at vegetable research farm, Department of Vegetable Science, Punjab Agricultural University, Ludhiana for “Identification and characterization of salt tolerant genotypes and salt tolerant gene in brinjal (Solanum melongena L.)” during the year 2016-18. The experiment was laid out in split plot design with four salinity levels (control, 2 dS/m, 4 dS/m and 6 dS/m) as main factor and 102 genotypes of brinjal as sub main factor. The desired levels of salinity were induced using sodium chloride, magnesium sulphate and calcium chloride in ratio 2:1:1 in field as well as in pot study. These genotypes were categorised as 19 genotypes under tolerant, 39 as semi-tolerant and 44 were susceptible to salinity on the basis of nursery and morphological screening trials. Tolerant genotypes were further evaluated for physico-chemicals characters. It has been observed from the investigation that plant growth and fruit characters of brinjal i.e. plant height, leaf area, root fresh and root dry weight; number of fruits per plant, fruit yield decreased as the salinity level increased. The results showed that brinjal genotypes SL-8-PB-1-3-1-4 followed by KBSR-343-1 and BL-215 performed better upto 4 dS/m levels of salinity with a slight decline in yield traits, while at 6 dS/m yield reduction was high, which was 12%, 28% and 28.5% respectively as compared to control. The total chlorophyll and carotenoid pigments of brinjal leaves decreased as the salinity level increased. Whereas, proline, protein, phenols and MDA content increased as the salinity level increased with maximum increase in SL-8-PB-1-3-1-4 genotype. Brinjal genotype SL-8-PB-1-3-1-4, KBSR-343-1 and BL-215 performed better for germination and survival rate at all salinity levels. By using NCBI database, SOS-3 gene sequence for brinjal was identified. Designed primer was amplified and the resulted PCR product was sent to Europhin Company for identification of haplotypes in brinjal. In the present investigation, SL-8-PB-1-3-1-4 (Small Long), KBSR-343-1 (Small round) and BL-215 (Long) emerged as ideal genotypes for growing under high salinity in field as well as pot conditions. Quality of these genotypes found least affected under salt stress. Thus, three brinjal genotypes (SL-8-PB-1-3-1-4 (Small Long), KBSR-343-1 (Small round) and BL-215 (Long)) may be recommended for future studies in salt affected area of Punjab.