PS Seminar Series- Understanding the wheat stem rust resistance immune receptors: from characterization to functional mechanisms

Abstract - The emergence of widely virulent Puccinia graminis f. sp. tritici (Pgt) races over the past two decades has motivated global efforts to identify effective stem rust (Sr) resistance genes. We isolate from wheat, Sr26 and Sr61, with both genes independently introduced as alien chromosome introgressions from tall wheat grass (Thinopyrum ponticum), both located on chromosome subgroup 6 distal region translocated segment. Mutational genomics and targeted exome capture identify Sr26 and Sr61 as separate single genes that encode unrelated (34.8%) nucleotide binding site leucine rich repeat proteins. The co-location of these genes on a small non-recombinogenic segment simplifies their deployment as a gene stack and potentially enhances their resistance durability.

To date, twelve seedling (or all stage) Sr genes (viz. Sr13, Sr21, Sr22, Sr26, Sr27, Sr33, Sr35, Sr45, Sr46, Sr50, Sr60, and Sr61) have been cloned, eleven of which encode coiled-coil, nucleotide-binding, leucine-rich-repeat (CNL) type immune receptors. In light of the recent revealed structure of CNL type R protein ZAR1 (HOPZ-ACTIVATED RESISTANCE 1), we have performed some functional analyses of these cloned Sr genes with a focus on their signalling domains.

Biography - Dr Zhang received her PhD from a joint program between the University of Sydney (PBI) and CSIRO (plant immunity group) on the study of wheat rust pathosystem (stem rust, stripe rust, and leaf rust) under the supervision of Prof Evans Lagudah, Dr Peng Zhang, and Prof Robert Park. She is now pursuing her interests in understanding the immune receptor functional mechanisms as a postdoc research fellow in the Dodds’s lab at CSIRO.