dhanashree-2106002@pau.edu

The biotic stresses diminished the production and quality of wheat crop, an important staple food crop for 40% of the world’s population. Among other diseases, the group of three rusts diseases are prominent causing losses as high as 10 –100% by stem rust (Puccinia graminis), 10 –70% by leaf rust (P. triticina) and 20 –100% by stripe rust (P. striiformis).

The monoculture of few wheat cultivars at global level makes these susceptible against prevalent rust races thus forcing to look for novel sources which could provide resistance. The wild species of wheat on other hand are goldmine of novel alleles due to their development under natural environmental conditions for multitude of years. About 1500 accessions of these wild wheat from 22 progenitor and non-progenitor species are being maintained at Punjab Agricultural University, Ludhiana and are being utilized for transferring and characterizing rust resistance in elite backgrounds.

Here we present the characterization and mapping of leaf rust (LR)/ stripe rust (YR) resistance genes transferred from four different species of Aegilops kotschyii, Aegilops peregrina, Aegilops speltoides, and Triticum dicoccoides. The introgression lines (ILs) carrying LR and YR resistance genes from each of these species was crossed with corresponding susceptible wheat line to examine the genetics of these transferred resistances.

The F2/3/4/5 mapping populations were screened against Indian predominant pathotypes of LR and YR at seedling and adult plant stage and genetic ratios were calculated. The IL from Ae. kotschyii (Lrkots) contain single LR resistance gene while those from Ae. speltoides (Lrsp3603 & Yrsp3603), Ae. peregrina (Lrper & Yrper) and T. dicoccoides (Lrdic & Yrdic) carry one LR and one YR resistance gene each. Mapping of these gene was done using combination of bulked segregant analysis with sequencing and/or 35K SNP chip. Lrkots was mapped to chromosome 3DL, with flanking SNP markers AX-94443154 (0.32cM) on proximal end and SSR Xbarc71 (7.9cM) on distal end defining a 3 Mb region containing eight candidate genes.

The Lrsp3603 and Yrsp3603, were mapped on chromosome 6B, with Lrsp3603 flanked by markers Tag-SSR14(2.42 cM) and SNP AX-94542331 (3.28 cM) and Yrsp3603 was mapped close to marker AX-94542331 at 6.62 cM. Lrper and Yrper were mapped on chromosome 3B with Lrper linked to marker AX-94449979 (7.5cM) and Yrper linked to AX-94482301 (10.7cM). Mapping of Lrdic at distance of 5cM to marker AX-95140906 on chromosome 1D while the KASP marker AX-94906888, situated at 404.1 Mb on chromosome 2D showed putative linkage with Yrdic (8cM).

Key words: rust resistance, Introgression lines, progenitor species, non-progenitor species, complementary gene interaction, all stage resistance genes