Redesigning the effectiveness of the stripe rust resistance gene Yr10 against current virulent fungal isolates

Stripe rust caused by Puccinia striiformis Westend. f. sp. tritici Erikss., (Pst), is an issue in every region of the world where wheat is grown. Ever evolving rust isolates are challenging the pool of resistance (R) genes in currently grown wheat cultivars. Although some R genes are still effective in specific regions, only two genes (Yr5, Yr15) are effective worldwide. Consequently, there is an urgent need to identify novel and effective resistance genes against different pathogens. The majority of known R genes in cereals and monocots belong to the CC-NBS-LRR group. Recently, roles for the coiled-coil (CC) and leucine-rich repeats (LRR) domains in the functioning of R genes for effective protection against pathogens have been shown. The Yr10 R gene, previously characterized and cloned in our lab, has been defeated in 2010 in southern Alberta but remains functional in central and northern Alberta. Modifications of R genes functional domains in Arabidopsis, rice and barley yielded alterations in the avirulence/virulence patterns of different pathogen isolates. We will report on modification to sequences of the CC and LRR domains of Yr10, and the rationale for such modifications. Additionally, we will describe our approach to insert modified Yr10 genes into the stripe rust susceptible wheat line Fielder. This work will demonstrate that target mutations toward improving the avirulence spectrum of a stripe rust R gene works within Canadian germplasm. This will also contribute to demonstrating that re-utilization of different ‘versions’ of defeated genes is an effective and efficient way for protecting wheat.