Immunity to stripe rust in wheat: A case study of a hypersensitive-response (HR)- independent resistance to Puccinia striiformis f. sp. tritici in Avocet-Yr15

Stripe (yellow) rust, caused by the biotrophic fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is emerging as a serious threat to wheat (Triticum aestivum L.) production in many regions of North America. Genetic resistance stripe rust typically conditioned products genes that detect pathogen-associated molecular patterns and initiate cascade signalling events, culminating generation reactive oxygen species (ROS) hypersensitive response (HR) eventually suppress pathogen. Complete with no symptoms (immunity response) has also been observed, but less frequently, certain Pst-wheat interactions. However, such HR-independent responses Pst have not well studied. Here we report Pst-resistant near isogenic line Avocet-Yr15 (carrying Yr15 gene) exhibited an immunity isolate collected Elora, Ontario, while Avocet-S (lacking Yr15) was highly susceptible same isolate. In particular, histochemical assays defence-associated ROS HR were negative during early stages interaction between resistant Avocet-Yr15. Microscopic analysis indicated able penetrate stomata Moreover, RNA-sequencing highlighted activation global anti-oxidative-stress consisting involved maintenance cell viability, redox homoeostasis photosynthesis. These results provide insights into mechanisms controlling wheat.