Wheat gene Sr60 encodes a protein with two putative kinase domains that confers resistance to stem rust

Abstract

Wheat stem rust, caused by Puccinia graminis Pers. f. sp. tritici (Pgt), is a devastating fungal disease threatening global wheat production. The present paper reports the identification of stem rust resistance gene Sr60, a race-specific gene from diploid wheat Triticum monococcum L. that encodes a protein with two putative kinase domains. This gene, designated as WHEAT TANDEM KINASE 2 (WTK2), confers intermediate levels of resistance to Pgt. WTK2 was identified by map-based cloning and validated by transformation of a c.10-kb genomic sequence including WTK2 into susceptible common wheat variety Fielder (Triticum aestivum L.). Transformation of Fielder with WTK2 was sufficient to confer Pgt resistance. Sr60 transcripts were transiently upregulated 1 d post-inoculation with Pgt, but not in mock-inoculated plants. The upregulation of Sr60 was associated with stable upregulation of several pathogenesis-related genes. The Sr60-resistant haplotype found in T. monococcum was not found in polyploid wheat, suggesting an opportunity to introduce a novel resistance gene. Sr60 was successfully introgressed into hexaploid wheat, and we developed a diagnostic molecular marker to accelerate its deployment and pyramiding with other resistance genes. The cloned Sr60 also can be a useful component of transgenic cassettes including other resistance genes with complementary resistance profiles.

A rare gain of function mutation in a wheat tandem kinase confers resistance to powdery mildew

“…Recently, TKP has emerged as a new class of disease resistance kinase protein family in plant innate immunity. Four plant disease resistance genes have been identified to contain a structure with tandem kinase domains, i.e., wheat stripe rust resistance gene Yr15 (WTK1) 35 , wheat stem rust resistance gene Sr60 (WTK2) 36 , barley (Hordeum vulgare L.) stem rust (P. graminis f. sp. tritici, Pgt) resistance gene Rpg1 37 , and the candidate gene (MLOC_38442.1) of barley loose smut (Ustilago nuda) resistance gene Un8 38 .…”

“…Yr15, Rpg1, and Un8 have been shown to provide a broadspectrum of disease resistance to their respective biotrophic fungal pathogens 35,37,38 . However, the race-specific stem rust resistance gene Sr60 conferred intermediate level of resistance to 3 of 8 tested Pgt races by delaying but not stopping the Pgt infection; therefore it is classified as a partial resistance gene 36 . In the current study, we showed that the Pm24 carrying accessions CYC, BHL, HLT, and HMM are resistant to all of the tested 93 Bgt isolates collected from 12 provinces of China.…”

Application of Genomics Tools in Wheat Breeding to Attain Durable Rust Resistance

“…These genes are believed to be regulated by NBS domains through signal transduction, and specific sites of corresponding pathogen virulence genes are recognized by LRR domains ( Gill et al., 2015 ). Six stripe rust resistance genes, Yr5/YrSP, Yr7, Yr10, Yr15, Yr36 , and YrAS2388R ( Fu et al., 2009 ; Liu H. et al., 2014 ; Klymiuk et al., 2018 ; Marchal et al., 2018 ; Zhang et al., 2019 ), four-leaf rust resistance genes Lr1, Lr10 , Lr21 , and Lr22a ( Feuillet et al., 2003 ; Huang et al., 2003 ; Cloutier et al., 2007 ; Thind et al., 2017 ), and nine major stem rust resistance genes, Sr33, Sr35, Sr50, Sr22, Sr45, Sr13, Sr46, Sr21 , and Sr60 ( Periyannan et al., 2013 ; Saintenac et al., 2013b ; Mago et al., 2015 ; Steuernagel et al., 2016 ; Zhang et al., 2017 ; Arora et al., 2018 ; Chen et al., 2018 ; Chen S. et al., 2020 ), and two pleiotropic APR ( Lr34/Yr18/Sr57 and Lr67/Yr46/Sr55 ) ( Krattinger et al., 2009 ; Moore et al., 2015 ) have been cloned ( Table 2 ).…”

Distribution and Nucleotide Diversity of Yr15 in Wild Emmer Populations and Chinese Wheat Germplasm

“…To date, three wheat resistance genes, stripe rust resistance gene Yr15 (WTK1) [20], stem rust resistance gene Sr60 (WTK2) [22], and powdery mildew resistance gene Pm24 (WTK3) [23], have been found to possess two tandem kinase (or pseudokinase) domains. Yr15 and Pm24 have been shown to confer a broader spectrum of disease resistance than Sr60.…”