M. V. C. GowdaVarsha Kumari2016-07-272016-07-272013http://krishikosh.egranth.ac.in/handle/1/69991In an attempt to broaden the genetic base and variability for late leaf spot (LLS) and rust resistance in groundnut, three introgression line (IL) populations, ICGS 76 × ISATGR 278-18 (IL1), DH 86 × ISATGR 278-18 (IL2) and DH 86 × ISATGR 5 (IL3) were developed by crossing disease susceptible varieties with the resistant synthetic amphidiploids (ISATGR 278-18 and ISATGR 5) and backcrossing twice with the recurrent parents. In total 164, 51 and 32 BC2F4 ILs constituted IL1, IL2 and IL3, respectively. Field evaluation of the ILs during kharif 2011, summer 2012 and kharif 2012 showed considerable variability and heritability for disease resistance and most of the agronomic and productivity traits. ILs showed bimodal distribution for LLS, and a normal distribution for rust and agronomic and productivity traits. LLS and rust were negatively correlated, while most of the agronomic and productivity traits were positively correlated. Most of the agronomic and productivity traits exhibited negative correlation with LLS and rust. Linkage mapping with 136 SSR markers in IL1 resulted in map of 1103.2 cM with 19 linkage groups and 8.62 cM inter-marker distance. Single marker analysis showed significant association of a few markers with R2 ranging from 3.94% to 94.34% for LLS and 3.96% to 68.337% for rust. GM1954 was consistent across the populations for both the diseases. Composite interval QTL mapping identified 26 QTL for disease resistance, and 16 for agronomic and productivity traits. Major QTL consistent across seasons included GM1996- IPAHM103 (31.12%-67.45%), gi-4925-GM2144 (9.70%-14.99%) and TC6E01-GM1409 (9.84%-12.39%) for LLS, gi-4925-GM2144 (10.40%-16.52%), GM2009-GM2301 (7.88%- 16.03%) and GM900-GM2082 (5.74%-11.04%) for rust and GM900-GM2082 (13.15%- 24.89%) for test weight. The markers flanking the major QTL carried the favorable alleles contributed by ISATGR 278-18, indicating the utility of wild diploids. QTL and the markers identified here need to be validated before deployed for marker assisted selection.Thesis