Zhu Xiuliang, Wang Yuanyuan, Su Zhenqi, Lv Liangjie, Zhang Zengyan
The National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China.
Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2018 Oct 31;9:1437. doi: 10.3389/fpls.2018.01437. eCollection 2018.
Eukaryotic type 2A protein phosphatases (protein phosphatase 2A, PP2A) consist of a scaffold subunit A, a regulatory subunit B, and a catalytic subunit C. Little is known about the roles of PP2Ac proteins that are involved in plant responses to necrotrophic fungal pathogens. Sharp eyespot, caused by the necrotrophic fungus , is a destructive disease of wheat (), an important staple food crop. Here, we isolated from wheat, which encodes a catalytic subunit of the heterotrimeric PP2A, and characterized its properties and role in plant defense response to . Based on the sequence alignment of with the draft sequences of wheat chromosomes from the International Wheat Genome Sequencing Consortium (IWGSC), it was found that gene is located on the long arm of the wheat chromosome 4D and has two homologs assigned on wheat chromosomes 4A and 4B. Sequence and phylogenetic tree analyses revealed that the TaPP2Ac protein is a typical member of the PP2Ac family and belongs to the subfamily II. and displayed higher transcriptional levels in the -susceptible wheat cultivar Wenmai 6 than those seen in the resistant wheat line CI12633. The transcriptional levels of and were significantly elevated in wheat after infection and upon HO treatment. Virus-induced gene silencing results revealed that the transcriptional knockdown of and significantly increased wheat resistance to infection. Meanwhile, the transcriptional levels of certain pathogenesis-related (PR) and reactive oxygen species (ROS)-scavenging enzyme encoding genes were increased in silenced wheat plants. These results suggest that TaPP2Ac-4B and TaPP2Ac-4D negatively regulate defense response to infection possibly through modulation of the expression of certain and ROS-scavenging enzyme genes in wheat. This study reveals a novel function of the plant PP2Ac genes in plant immune responses.
真核2A型蛋白磷酸酶（蛋白磷酸酶2A，PP2A）由一个支架亚基A、一个调节亚基B和一个催化亚基C组成。关于参与植物对坏死营养型真菌病原体反应的PP2Ac蛋白的作用，人们了解甚少。由坏死营养型真菌引起的小麦眼斑病是小麦（一种重要的主食作物）的一种毁灭性病害。在这里，我们从小麦中分离出了 ，它编码异源三聚体PP2A的催化亚基，并对其特性以及在植物对 的防御反应中的作用进行了表征。基于 与国际小麦基因组测序联盟（IWGSC）的小麦染色体草图序列的比对，发现 基因位于小麦4D染色体的长臂上，并且在小麦4A和4B染色体上有两个同源基因。序列和系统发育树分析表明，TaPP2Ac蛋白是PP2Ac家族的典型成员，属于亚家族II。 在感病小麦品种温麦6中的转录水平高于抗病小麦品系CI12633。 在感染 和经HO处理后的小麦中， 和 的转录水平显著升高。病毒诱导的基因沉默结果表明， 和 的转录水平降低显著提高了小麦对 感染的抗性。同时，在沉默的小麦植株中，某些病程相关（PR）和活性氧（ROS）清除酶编码基因的转录水平有所增加。这些结果表明，TaPP2Ac - 4B和TaPP2Ac - 4D可能通过调节小麦中某些 和ROS清除酶基因的表达来负向调节对 感染的防御反应。本研究揭示了植物PP2Ac基因在植物免疫反应中的新功能。
