Application of High Density Linkage Map Derived from Genotyping by Sequencing for Detection of QTL Conferring Resistance to Leaf Rust Races Spread in Egypt

Abstract

Wheat is a major source of carbohydrates in Egypt, leaf rust disease is known to be the most common rust disease affected wheat genotypes. This study aimed to apply a constructed high density linkage map through Genotyping-by- sequencing (GBS) for detection of QTL resistant to important leaf rust races spread in Egypt. The applied map contained 3,641 markers distributed on 21 chromosomes and spanned 1,959 cM with an average distance of 1.8 cM between markers. A mapping population of 204 RILs (F6:8) obtained from the cross between two parents of winter wheat ‘Harry’ x ‘Wesley’ through single seed decent method was used to identify QTL region associated with leaf rust resistance genes in wheat. Under the Green house condition in Egypt leaf rust pathotypes i.e NTTJT, PTTGS, PTTTT, TTTBT and TTTTT were used. High-density linkage map based on GBS derived SNPs were applied in this study for QTL mapping. The wheat genotype Harry was resistant to all tested pathotype while, the wheat genotype Wesley was susceptible to all tested pathotype. One major stable QTLs, for race NTTJT was identified on chromosome 6A flanked by markers XSNP3958 and XSNP3957 with a LOD 4.22. The identified SNP marker may be used to screen for resistance to specific races of leaf rust found in Egypt in further spring wheat breeding programs as marker assisted selection.