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20181
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Subject: Genetics and Plant Breeding × Author: Arora, Naveen × Start date: 2000 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Assessment of genetic diversity of shoot fly-resistant sources and transfer QTLs associated with shoot fly resistance into forage sorghums (Sorghum bicolor L.)
    (Punjab Agricultural University, Ludhiana, 2018) Arora, Naveen; Sohu, R.S.
    The present study consisted of two different sets of genotypes evaluated for variable reaction to shoot fly under field conditions. The first set consisted of a diverse collection of 53 different germplasm lines and the second set consisted of 30 genotypes including 10 cytoplasmic male sterile lines, along with their respective maintainers and 10 restorer lines. On the basis of morphological evaluation under field conditions, the genotypes varied significantly for all the traits under study. ICSA/B 487, ICSA/B 14037, ICSA/B 467, ICSV 93046 and ICSV 700 exhibited high glossiness, pigmented leaf sheath, lower number of eggs and suffered lesser incidence of deadhearts and exhibited resistant reaction to shoot fly while ICSA/B 458, ICSV 25337 and ICSV 25292 exhibited moderate resistance to the shoot fly damage and ICSV- 25280, 25292, 25303, 25316, BTx 623, SSV 74 and Swarna were susceptible to shoot fly. In the germplasm lines significant variation was found for most of the traits except the leaf sheath pigmentation, number of plants with shoot fly eggs and number of shoot fly eggs per plant. Significant positive and negative correlations were found among the important traits for shoot fly resistance like glossy score, leaf sheath pigmentation, shoot fly deadhearts, total number of eggs, number of plants with eggs and trichome density. The inheritance studies based on Line X Tester analysis, revealed that shoot fly resistance is a complex trait and crosses involving resistant parents yielded resistant lines. The lines ICSA 458, ICSA 467, ICSA 487, ICSA 14024 and ICSA 14037 and testers ICSV 700, ICSV 93046, S-35, ICSV 25292 and ICSV 25337 had significant SCA and GCA effects for the traits important for shoot fly resistance. The estimation of biochemical components, revealed that the genotypes exhibiting moderate (ICSA 84, ICSB 52, ICSB 14024) and high (ICSA 467, and ICSB 487) resistance to shoot fly recorded lesser content of total soluble sugars, proteins, higher content of tannins and there was no significant association found for phenol content. From the HPLC analysis of methanol extracts of leaf samples a total of 25 different peaks with 12 known compounds were recorded. Diversity analysis based on GBS based SNP markers grouped the germplasm and parental lines into three major clusters consisting of resistant, moderately resistant and susceptible genotypes. Population structure was analysed using principle component analysis. The first three PC were sufficient enough to explain maximum diversity within population structure. For Genome Wide Association Studies, first three PCs were used as a covariate for which, significant association of SNPs were found for glossy score on chromosome 3, 9, 10 and for percent plants with shoot fly eggs on chromosome 2. For leaf sheath pigmentation, SNPs on all the chromosomes were significantly associated. Similarly, multiple SNPs were associated for percent tiller with shoot fly deadhearts on chromosomes 2,3,4,6,7 and 9. SNPs for plant vigour score were significantly associated with chromosomes 1,2,3 and 6.