QTL MAPPING FOR GRAIN AND YIELD RELATED TRAITS IN BREAD WHEAT (TRITICUM AESTIVUM L.)

Abstract

An F2 mapping population derived from two contrasting bread wheat parents, PHS 1107 (low tillering) and Lok 1 (high tillering) was evaluated to identify genomic regions controlling tiller number and yield related traits using SSR markers. Among 133 SSK markers screened, 29 markers showed polymorphism and were used for genotyping 70 F2 plants. All markers segregated according to the expected Mendelian ratio (1:2:1) indicating suitability for linkage analysis. A genetic linkage map comprising seven linkage groups was constructed using covering a total map length of 394.04 cM, with linkage groups ranging from 36.83 cM (LG7) to 80.86 cM (LG6). QTL analysis based on phenotypic data of F2 lines identified six QTLs associated with important agronomic traits. A major QTL for tiller number per plant, qNTPP 4-1 was detected on linkage group 4 between markers Xgwm194 and Xcfd71 with a LOD score of 15.87 explaining 68.26% phenotypic variation. Two QTLs for plant height qPH-4-1 and qPH-6-1 explained 17.70% and 27.09% variation, respectively. A major QTL for 1000 grain weight, qTGW-5-1 was identified on linkage group 5 with 42.20% phenotypic variation. One QTL for grain yield per plant, qGYPP-1-1 was mapped on linkage group 1 explaining 32.64% variation. Another major QTI, QNGPS-4-1, controlling grains per spike, was located on linkage group 4 with 66.66% variation. Linkage group 4 emerged as an important genomic region harboring multiple yield related QTLs. The Identified marker-trait associations provide useful tools for marker-assisted selection and pyramiding of favorable alleles to develop high-yielding, well-adapted wheat cultivars with improved tillering ability, grain weight, plant architecture, and yield stability.