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Summary: The LRK10‐like receptor kinases (LRK10L‐RLKs) are ubiquitously present in higher plants, but knowledge of their expression and function is still limited. Here, we report expression and functional analysis of TtdLRK10L‐1, a typical LRK10L‐RLK in durum wheat (Triticum turgidum L. ssp. durum). The introns of TtdLRK10L‐1 contained multiple kinds of predicted cis‐elements. To investigate the potential effect of these cis‐elements on TtdLRK10L‐1 expression and function, two types of transgenic wheat lines were prepared, which expressed a GFP‐tagged TtdLRK10L‐1 protein (TtdLRK10L‐1:GFP) from the cDNA or genomic DNA (gDNA) sequence of TtdLRK10L‐1 under the native promoter. TtdLRK10L‐1:GFP expression was up‐regulated by the powdery mildew pathogen Blumeria graminis f. sp. tritici (Bgt) in both types of transgenic plants, with the scale of the elevation being much stronger in the gDNA lines. Both types of transgenic plants exhibited enhanced resistance to Bgt infection relative to wild type control. Notably, the Bgt defence activated in the gDNA lines was significantly stronger than that in the cDNA lines. Further analysis revealed that a putative MYB transcription factor binding site (MYB‐BS, CAGTTA) located in TtdLRK10L‐1 intron I was critical for the efficient expression and function of TtdLRK10L‐1 in Bgt defence. This MYB‐BS could also increase the activity of a superpromoter widely used in ectopic gene expression studies in plants. Together, our results deepen the understanding of the expression and functional characteristics of LRK10L‐RLKs. TtdLRK10L‐1 is likely useful for further dissecting the molecular processes underlying wheat defence against Bgt and for developing Bgt resistant wheat crops. [ABSTRACT FROM AUTHOR]

Summary: Powdery mildew disease, elicited by the obligate fungal pathogen Blumeria graminis f.sp. tritici (Bgt), causes widespread yield losses in global wheat crop. However, the molecular mechanisms governing wheat defense to Bgt are still not well understood.Here we found that TuACO3, encoding the 1‐aminocyclopropane‐1‐carboxylic acid (ACC) oxidase functioning in ethylene (ET) biosynthesis, was induced by Bgt infection of the einkorn wheat Triticum urartu, which was accompanied by increased ET content. Silencing TuACO3 decreased ET production and compromised wheat defense to Bgt, whereas both processes were enhanced in the transgenic wheat overexpressing TuACO3.TuMYB46L, phylogenetically related to Arabidopsis MYB transcription factor AtMYB46, was found to bind to the TuACO3 promoter region in yeast‐one‐hybrid and EMSA experiments. TuMYB46L expression decreased rapidly following Bgt infection. Silencing TuMYB46L promoted ET content and Bgt defense, but the reverse was observed when TuMYB46L was overexpressed.Hence, decreased expression of TuMYB46L permits elevated function of TuACO3 in ET biosynthesis in Bgt‐infected wheat. The TuMYB46L‐TuACO3 module regulates ET biosynthesis to promote einkorn wheat defense against Bgt. Furthermore, we found four chitinase genes acting downstream of the TuMYB46L‐TuACO3 module. Collectively, our data shed a new light on the molecular mechanisms underlying wheat defense to Bgt. [ABSTRACT FROM AUTHOR]