Genetic linkage mapping in walnut (Juglans regia L.) by DNA markers

This study was carried out to construct the most dense genetic linkage map of walnut for future molecular breeding studies. An F1 population created by crossing Maraş-12 and Kaplan-86 walnut cultivars was used, and the 'double pseudo-testcross' mapping strategy was applied to construct the parental genetic linkage maps. AFLP, SRAP and SSR techniques were used in the analysis, and 360, 240 and 319 primer pairs were firstly screened, respectively. The 45 AFLP, 40 SRAP, 122 SSR markers were used in the analysis of F1 population, and the segregated 452 AFLP, 383 SRAP, and 129 SSR markers were scored. Of them, 379 AFLP, 294 SRAP, and 96 SSR markers were mapped. The number of mapped markers per primer pair was 8.42 in AFLP, 7.35 in SRAP, and was 0.79 in SSR. Maras-12 cultivar genetic map had 492 markers (68 SSRs, 191 SRAPs, 233 AFLPs) with 1407 cM total length, while Kaplan-86 genetic map had 461 markers (57 SSRs, 191 SRAPs, 213 AFLPs) with 1426 cM total map length. Marker density was 2.86 in Maraş-12 maternal map, while it was 3.09 in Kaplan-86 paternal map. In conclusion, the most dense genetic linkage maps were constructed in this study for walnut.