Genetic Mapping and Quantitative Trait Loci Analysis for Disease Resistance Using F2 and F5 Generation-based Genetic Maps Derived from 'Tifrunner' x 'GT-C20' in Peanut

One mapping population derived from Tifrunner x GT-C20 has shown great potential in developing a high density genetic map and identifying quantitative trait loci (QTL) for important disease resistance, tomato spotted wilt virus (TSWV) and leaf spot (LS). Both F-2 and F-5 generation-based genetic maps were previously constructed with 318 and 239 marker loci, respectively. Higher map density could be achieved with the F-2 map (5.3 cM per locus) as compared to the F-5 (5.7 cM per locus). Quantitative trait loci analysis using multi-environment phenotyping data from F-8 and higher generations for disease resistance identified 54 QTL in the F-2 map including two QTL for thrips (12.14-19.43% phenotypic variation explained [PVE]), 15 for TSWV (4.40-34.92% PVE), and 37 for LS (6.61-27.35% PVE). Twenty-three QTL could be identified in the F-5 map including one QTL for thrips (5.86% PVE), nine for TSWV (5.20-14.14% PVE), and 13 for LS (5.95-21.45% PVE). Consistent QTL identified in each map have shown higher phenotypic variance than nonconsistent QTL. As expected, the number of QTL and their estimates of phenotypic variance were lower in the F-5 map. This is the first QTL study reporting novel QTL for thrips, TSWV, and LS in peanut (Arachis hypogaea L.), and therefore, future studies will be conducted to refine these QTL.