State Key Laboratory of North China Crop Improvement and Regulation, Key Laboratory of Hebei Province for Plant Physiology and Molecular Pathology, College of Life Sciences, Hebei Agriculture University, Baoding, China.
CSIRO Plant Industry, QLD, Australia.
Mol Plant Pathol. 2020 May;21(5):732-746. doi: 10.1111/mpp.12929. Epub 2020 Mar 20.
Leaf rust, caused by Puccinia triticina, is one of the most destructive fungal diseases in wheat production worldwide. The hypersensitive reaction (HR) is an important defence response against P. triticina infection. In this study, the physiological races 165 and 260 of P. triticina were combined with a line derived from the bread wheat cultivar Thatcher with the leaf rust resistance locus Lr26 to form compatible and incompatible combinations, respectively. Based on an RNA-Seq database of the interaction systems, a new wheat cysteine-rich receptor-like kinase gene, TaCRK2, is specifically induced and up-regulated in the incompatible combination. We identified that TaCRK2 was regulated in a Ca -dependent manner. Knockdown of TaCRK2 by virus-induced gene silencing and RNAi leads to a dramatic increase in HR area and the number of haustorial mother cells at the single infection site. In addition, urediniospores, a P. triticina-specific pathogenic marker in compatible combinations, were observed on leaf surfaces of silenced plants at approximately 15 days after inoculation in the incompatible combination. Moreover, transcription levels of TaPR1, TaPR2, and TaPR5 were obviously reduced in TaCRK2-silenced plants. TaCRK2 overexpression in Nicotiana benthamiana induced strong HR-like cell death. Finally, transient expression of green fluorescent protein fused with TaCRK2 in N. benthamiana indicated that TaCRK2 localizes in the endoplasmic reticulum. Thus, TaCRK2 plays an important role in the resistance to P. triticina infection and has a positive regulation effect on the HR cell death process induced by P. triticina.
叶锈病是由小麦叶锈菌引起的，是全球小麦生产中最具破坏性的真菌病害之一。过敏性反应（HR）是小麦抵御小麦叶锈菌感染的重要防御反应。在本研究中，小麦叶锈菌的生理小种 165 和 260 与源自面包小麦品种 Thatcher 的具有叶锈病抗性基因 Lr26 的系分别形成了亲和和非亲和组合。基于互作系统的 RNA-Seq 数据库，我们鉴定到一个新的小麦富含半胱氨酸的受体样激酶基因 TaCRK2，它在非亲和组合中被特异性诱导和上调。我们发现 TaCRK2 的调控依赖于 Ca2+。通过病毒诱导的基因沉默和 RNAi 敲低 TaCRK2 导致 HR 面积和单个感染部位吸器母细胞数量的显著增加。此外，在非亲和组合中，沉默植株的叶片表面大约在接种后 15 天观察到亲和组合中 P. triticina 特有的致病性标记——夏孢子。此外，在 TaCRK2 沉默植株中，TaPR1、TaPR2 和 TaPR5 的转录水平明显降低。在本氏烟草中过表达 TaCRK2 诱导强烈的 HR 样细胞死亡。最后，在本氏烟草中瞬时表达与 TaCRK2 融合的绿色荧光蛋白表明 TaCRK2 定位于内质网。因此，TaCRK2 在小麦对 P. triticina 感染的抗性中发挥重要作用，并对 P. triticina 诱导的 HR 细胞死亡过程具有正向调控作用。
