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2011 - 20122
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Subject: Plant Biotechnology × Start date: 2010 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Candidate Gene Mapping, Pyramiding of Stay-Green and Water use Efficiency Qtls and Mapping of Putative Qtls for Root Traits using Ril Populations in Sorghum
    (UAS Dharwad, 2012) Rajkumar; B. Fakrudin
    Recombinant Inbred Populations (RIPs) derived from the crosses IS9830 x E36-1 (RIP1) and N13 x E36-1 (RIP2) were used to map localize the drought tolerance-related candidate genes through SNPs. A total of five QTLs flanked by at least one candidate gene (SNP) were found common across both RIPs: qGLA3 (Xtxp38-Xsnp19); qGLA4 (Xiabt227-Xsnp56) qDAF2 (Xiumc136-Xsnp28) qPL4 (Xisp229-Xsnp36) and qSY4 (Xsnp36-Xtxp27). The three stable QTLs for stay-green, qSTG1A:Xtxp34-Xtxp285; qSTG2: Xtxp205-Xtxp231; qSTG3:Xtxp298-Xtxp324 and one QTL for water use efficiency, qCID2:Xtxp6-Xiabt70 were introgressed from E36-1 the stay-green parent into SPV86, SPV570 and M35-1. The foreground and limited background screening across BC1F1, BC2F1, and BC3F1 generations was done and the BC3F2 progenies with various QTL combinations in homozygous condition were identified and selfed. The BC3F3 near isogenic lines (NIL) were evaluated in greenhouse: NIL with all four QTLs in M35-1 (75.83 %), SPV86 (78.48 %) and SPV570 (75.57 %) backgrounds showed per cent green leaf area (GLA) retention on par to the stay-green donor parent (E36-1, 75.20 %) at physiological maturity. The two RIPs: E36-1 x Basavanapada (RRIP1) and E36-1 x SPV70 (RRIP2) segregating for high root volume and root length respectively were field evaluated during rabi 2010-11. Analysis of variance revealed significance difference among the RILs. A total of 113 (55/530 EST-SSRs, 40/275 SSRs, 18/138 SNPs) and 104 (50/530 EST-SSRs, 34/270 SSRs, 20/138 SNPs) polymorphic markers were genotyped to construct a genetic linkage map spanning 1633 cM and 1800.1 cM, and a total of 30 and 28 putative QTLs were mapped for root and yield related traits in RRIP1 and RRIP2, respectively. The lack of overlap between the QTLs of component traits of root and yield, suggested that these two parameters are independent and the possibility of combining these two traits, favorably to enhance productivity of sorghum under receding moisture condition.
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    ThesisItemOpen Access
    Genome-Wide QTL Mapping for Post-Flowering Drought Tolerance and Validation of Charcoal Rot Resistance QTLs in NILs of Sorghum
    (UAS Dharwad, 2011) Suvarna Patil; B. Fakrudin
    Two Recombinant Inbred Line Populations (RIP) derived from the cross IS9830 x E36-1 (RIP1) and N13 x E36-1 (RIP2) were field evaluated for stay-green and yield related traits during rabi season at two locations over three years. Parents IS9830 and N13 were non-stay-green and E36-1 was a stay-green donor. Analysis of variance showed positive significant association in both RIPs. A total of 530 genic and 270 nuclear SSR markers were screened to finally genotype 40 genic, 71 nuclear SSR markers for RIP1 and 68 genic and 70 nuclear SSR for RIP2 to construct genetic linkage maps together with 46 anchor markers. The genetic linkage maps spanned over 1661.1 cM and 2003.8 cM for RIP1 and RIP2, respectively. Same were used for mapping the stable QTLs for stay-green components: stg1 (GLA15DAF) flanked by Xtxp34-Xtxp285 on LG-A, stg2 (GLA30DAF) flanked by Xtxp205-Xtxp231 on LGE, stg3 (GLA45DAF) flanked by Xtxp298-Xtxp324 on LG-J and dC flanked by Xtxp6-Xiabt73 on LG-I, together accounting for 40.91 and 48.76 per cent of phenotypic variance in RIP1 and RIP2, respectively; the positive additive effects at all the loci was contributed by E36-1. The stable QTLs for other yield related traits were also mapped. The stable QTLs for component traits of charcoal rot resistance viz., cr1 (Xtxp176-Xiabt312) for lodging per cent on LG-I, cr2 (Xtxp297-Xiabt173) for number of internodes crossed by the fungus on LG-B and cr3 (Xiabt275-Xiabt241) for length of infection on LG-I were introgressed from E36-1 into M35-1 and SPV86 susceptible backgrounds with recurrent foreground and background screening across BC1F1, BC2F1, BC3F1 generations and the BC3F2 progenies with various QTLs combinations in homozygous condition pinned down. The BC3G3 near isogenic lines (NILs) were evaluated: NILs with all the 3 QTLs recorded lodging per cent of 0.9 and 1.2 against 41.46 and 53.38 per cent incidence in controls, respectively in M35-1 and SPV86 backgrounds. The next best NIL in both backgrounds carried cr1 and cr2. These NILs have immediate practical utility as resistant versions.