The NB‐LRR gene Pm60 confers powdery mildew resistance in wheat

Abstract

Powdery mildew is one of the most devastating diseases of wheat. To date, few powdery mildew resistance genes have been cloned from wheat due to the size and complexity of the wheat genome. Triticum urartu is the progenitor of the A genome of wheat and is an important source for powdery mildew resistance genes. Using molecular markers designed from scaffolds of the sequenced T. urartu accession and standard map-based cloning, a powdery mildew resistance locus was mapped to a 356-kb region, which contains two nucleotide-binding and leucine-rich repeat domain (NB-LRR) protein-encoding genes. Virus-induced gene silencing, single-cell transient expression, and stable transformation assays demonstrated that one of these two genes, designated Pm60, confers resistance to powdery mildew. Overexpression of full-length Pm60 and two allelic variants in Nicotiana benthamiana leaves induced hypersensitive cell death response, but expression of the coiled-coil domain alone was insufficient to induce hypersensitive response. Yeast two-hybrid, bimolecular fluorescence complementation and luciferase complementation imaging assays showed that Pm60 protein interacts with its neighboring NB-containing protein, suggesting that they might be functionally related. The identification and cloning of this novel wheat powdery mildew resistance gene will facilitate breeding for disease resistance in wheat.

Mechanisms of powdery mildew resistance of wheat – a review of molecular breeding

“…In wheat, arrays of powdery mildew R genes ( Pm genes and temporarily designated genes) and alleles have been documented over 30 years, and in this review we have provided an updated list based on current knowledge (Table ). Of these powdery mildew resistance genes documented in the wheat gene pool, only six ( Pm2 , Pm3 , Pm8 , Pm17 , Pm21 , and Pm60 ) have been cloned to date, all encoding proteins of the NLR class (Yahiaoui et al , 2004; Cao et al , 2011; Hurni et al , 2013; Sanchez‐Martin et al , 2016; Xing et al , 2017; He et al , 2018; Singh et al , 2018; Zou et al , 2018). The gene‐for‐gene interaction always results in the host having a full resistance rating to the pathogen.…”

Discovery of powdery mildew resistance gene candidates fromAegilops biuncialischromosome 2Mbbased on transcriptome sequencing

“…However, some cloned genes of disease resistance in plants were reported to be not significantly up-regulated expression after pathogens inoculation. For example, Zou et al (2017) cloned wheat powdery mildew resistance gene Pm60 using standard map-based cloning, and showed that the transcript levels of Pm60 were no significantly difference after Bgt E09 infection at various time points by qRT-PCR [9]. In addition, Li et al (2017) discovered the expression level of broad-spectrum blast resistance gene bsr-d1 in rice was also not induced before and after blast infection [41].…”

“…Of which, 4,382 unigenes were differentially expressed genes (DEGs) in TA7733 post vs before Bgt -inoculation, and the remaining 2,896 unigenes had expression levels of no significant difference. In consideration of the fact that expression levels of some cloned resistance genes did show no significant difference before and after pathogen infection [9,41], we also take into account these 2,896 unigenes as putative candidate genes involved in powdery mildew resistance from chromosome 2M b .…”

“…Wild relatives of common wheat contain a large number of Bgt resistance genes for wheat improvement. Up to now, the number of designated genes of powdery mildew resistance was more than 80 at 54 loci [8,9], of which approximately half of the powdery mildew resistance genes ( Pm ) were derived from wild relatives of common wheat. However, some Pm genes had been defeated by new virulent races or by races that were previously present at very low frequencies in the pathogen population [10,11], and some were difficult to use in wheat breeding because of linkage drags [12,13].…”

“…For example, Li et al (2016) obtained eight powdery mildew resistance related genes from Thinopyrum intermedium by RNA-seq analysis [35]. Zou et al (2018) successfully isolated a powdery mildew resistance gene Pm60 from T. urartu by combining genetic mapping and RNA-seq analysis [9].…”