Fine mapping and characterization of stripe rust resistance gene YrAYH in near-isogenic lines derived from a cross involving wheat landrace Anyuehong

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a devastating disease in wheat worldwide. Discovering and characterizing new resistance genes/QTL is crucial for wheat breeding programs. In this study, we fine-mapped and characterized a stripe rust resistance gene, YRAYH, on chromosome arm 5BL in the Chinese wheat landrace Anyuehong (AYH). Evaluations of stripe rust response to prevalent Chinese Pst races in near-isogenic lines derived from a cross of Anyuehong and Taichung 29 showed that YrAYH conferred a high level of resistance at all growth stages. Fine mapping using a large segregating population of 9,748 plants, narrowed the YRAYH locus to a 3.7 Mb interval on chromosome arm 5BL that included 61 annotated genes. Transcriptome analysis of two NIL pairs identified 64 upregulated differentially expressed genes (DEGs) in the resistant NILs (NILs-R). Annotations indicated that many of these genes have roles in plant disease resistance pathways. Through a combined approach of fine-mapping and transcriptome sequencing, we identified a serine/threonine-protein kinase SRPK as a candidate gene underlying YrAYH. A unique 25 bp insertion was identified in the NILs-R compared to the NILs-S and previously published wheat genomes. An InDel marker was developed and co-segregated with YrAYH. Agronomic trait evaluation of the NILs suggested that YrAYH not only reduces the impact of stripe rust but was also associated with a gene that increases plant height and spike length.