| Wheat is the third most staple food worldwide but current 1% annual improvement in the wheat production is insufficient to meet the growing demands in future. The narrow genetic base of wheat limits continuous improvement in wheat productivity and tolerance to biotic and abiotic stress under changing climate. Wild ancestors and relatives of wheat hold a potential in widening the genetic pool of the wheat and enhance it resilience to biotic and abiotic stresses. This study was focused towards characterizing genetic diversity in wild relatives of wheat for disease resistance and efficient association with diazotrophs. In the first study, we evaluated a mini core set of Triticum turgidum subsp. (tetraploid wheat, AABB) for resistance to Fusarium head blight (FHB), leaf rust and tan spot. Three, six, and nine accessions showed resistance response to Fusarium head blight (FHB), leaf rust and tan spot respectively. These germplasm could be further exploited in wheat breeding. In the second study, in addition to tetraploid wheat, diploid and hexaploid germplasm of both wild and adapted species was evaluated for efficient association with diazotrophic bacteria by analyzing the N content. We observed significant differences for 15N content among different species, represented as average sigma15N. Lower sigma15N indicates a higher possibility of biologically fixed nitrogen (BNF). Wild accessions both in diploid (T. boeticum , AmAm, sigma15N = 20.85) and tetraploid species (T. turgidum subsp. dicoccoides, AABB, sigma15N = 16.44) showed significantly better associations with diazotrophs as compared to domesticated species ( T. monococcum, AmAm, sigma 15N = 26.67) and modern hexaploid varieties (T. aestivum, AABBDD, sigma15N =31.74). Our study shows wild species hold a promise in identification and characterization of efficient association with diazotrophic bacteria and can be recovered into modern cultivars of wheat to enhance the performance of wheat in marginal soils. In the final study, we analyzed the genetic diversity in the global collection (178 accessions) of rye using 4,037 high-quality SNPs and developed of a mini core set of 32 accessions of rye that represents more than 95 % of the allelic diversity (PIC = 0.25) of our collection (PIC = 0.26). Genome-wide association studies (GWAS) was performed on 160 accessions (Secale cereale subsp. cereale) with 4,037 high-quality SNPs to identify genomic regions conferring tan spot resistance. Nearly 32%, 27%, 24%, and14% accessions showed resistant, moderately resistant, moderately susceptible and susceptible reaction to Pyrenophora tritici-repentis race 5 (PTR5) respectively. Two QTLs conferring resistance to tan spot (PTR5) were identified (p= <0.001) using mixed linear model (GAPIT) on chromosomes 5R and 2R. The QTLs QTs-sdsu-5R and QTs-sdsu-2R explained 9 % and 9.7 % of the variation. In conclusion, wild relatives and ancestors of wheat hold a potential for wheat improvement especially for tolerance to abiotic and biotic factors. |
