Abstract
A major QTL explaining up to 82.62% of phenotypic variation for rust resistance was introgressed into three popular peanut varieties (TAG 24, ICGV 91114, JL 24) using marker-assisted backcrossing (MABC) approach. The donor parent, GPBD 4 derived its resistance from one of its interspecific parent, ICGV 86855 (CS 16), which in turn received from a diploid wild species, Arachis cardenasii. Four linked markers (IPAHM103, GM2079, GM1536, and GM2301) present in the QTL region were employed for foreground selection.
Preliminary yield evaluation of 51 introgression lines (ILs) (17 of TAG 24, 13 of ICGV 91114 and 21 of JL 24) along with parents and checks showed significant differences among the lines for yield parameters and rust resistance. The pod yield of ILs was up to 56-96% higher than recurrent parents. The superior pod yield in ILs is in part attributed to pod yield protection offered by resistance. The ILs were resistant to rust with a disease score of 2.0 or 2.5 at 90 DAS (on 1-9 scale) similar to donor parent, while the recurrent parents had higher score (5.0 in TAG 24, 6.5 in ICGV 91114, 7.0 in JL 24). Disease progress from 75 to 90 days was slower in ILs. The differences were not significant for days to flowering between ILs and their respective recurrent parents. Combining disease resistance and early maturity in peanut varieties is the most significant outcome. Further evaluations and promotion of promising ILs to multi location evaluation will facilitate nominations to varietal release trials.