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.

中文翻译：

---

TuMYB46L-TuACO3模块可调节单核小麦防御白粉病中的乙烯生物合成。

由专性真菌病原体Blumeria graminis f.sp.引起的白粉病。Tritici（Bgt）导致全球小麦作物普遍减产。但是，控制小麦防御Bgt的分子机制仍然不很清楚。在这里我们发现，TuACO3编码在乙烯（ET）生物合成中起作用的1-氨基环丙烷-1-羧酸（ACC）氧化酶，是由Bgt感染单核小麦Triticum urartu的Bgt感染引起的，并伴有ET含量增加。沉默TuACO3会降低ET的产生并损害小麦对Bgt的防御，而在过表达TuACO3的转基因小麦中这两个过程均得到增强。与拟南芥MYB转录因子AtMYB46系统发育相关的TuMYB46L在酵母单杂交和EMSA实验中发现与TuACO3启动子区域结合。Bgt感染后，TuMYB46L表达迅速下降。沉默TuMYB46L促进了ET含量和Bgt防御，但是当TuMYB46L过表达时，观察到相反的情况。因此，减少的TuMYB46L表达使TuACO3在Bgt感染小麦的ET生物合成中的功能得以提高。TuMYB46L-TuACO3模块调节ET生物合成，以促进小麦对Bgt的防御。此外，我们发现了在TuMYB46L-TuACO3模块下游起作用的四个几丁质酶基因。总体而言，我们的数据为小麦防御Bgt的分子机制提供了新的思路。TuMYB46L表达的降低使TuACO3在Bgt感染小麦的ET生物合成中的功能增强。TuMYB46L-TuACO3模块调节ET生物合成，以促进小麦对Bgt的防御。此外，我们发现了在TuMYB46L-TuACO3模块下游起作用的四个几丁质酶基因。总体而言，我们的数据为小麦防御Bgt的分子机制提供了新的思路。TuMYB46L表达的降低使TuACO3在Bgt感染小麦的ET生物合成中的功能增强。TuMYB46L-TuACO3模块调节ET生物合成，以促进小麦对Bgt的防御。此外，我们发现了在TuMYB46L-TuACO3模块下游起作用的四个几丁质酶基因。总体而言，我们的数据为小麦防御Bgt的分子机制提供了新的思路。