Table_3_MeWRKY IIas, Subfamily Genes of WRKY Transcription Factors From Cassava, Play an Important Role in Disease Resistance.XLS

Cassava (Manihot esculenta Crantz) is an important tropical crop for food, fodder, and energy. Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. manihotis (Xam) occurs in all cassava growing regions and threatens global cassava production. WRKY transcription factor family plays the essential roles during plant growth, development, and abiotic or biotic stress. Particularly, previous studies have revealed the important role of the group IIa WRKY genes in plant disease resistance. However, a comprehensive analysis of group IIa subfamily in cassava is still missing. Here, we identified 102 WRKY members, which were classified into three groups, I, II, and III. Transient expression showed that six MeWRKY IIas were localized in the nucleus. MeWRKY IIas transcripts accumulated significantly in response to SA, JA, and Xam. Overexpression of MeWRKY27 and MeWRKY33 in Arabidopsis enhanced its resistance to Pst DC3000. In contrast, silencing of MeWRKY27 and MeWRKY33 in cassava enhanced its susceptibility to Xam. Co-expression network analysis showed that different downstream genes are regulated by different MeWRKY IIa members. The functional analysis of downstream genes will provide clues for clarifying molecular mechanism of cassava disease resistance. Collectively, our results suggest that MeWRKY IIas are regulated by SA, JA signaling, and coordinate response to Xam infection.

木薯（Manihot esculenta Crantz）是一类重要的热带作物，可应用于食品、饲料及能源生产。由野油菜黄单胞菌木薯致病变种（Xanthomonas axonopodis pv. manihotis, Xam）引发的木薯细菌性枯萎病（CBB）在全球所有木薯种植区均有发生，对全球木薯生产造成严重威胁。WRKY转录因子家族（WRKY）在植物生长发育以及非生物、生物胁迫响应过程中发挥关键作用。既往研究已揭示IIa亚族WRKY基因在植物抗病过程中的重要功能。然而，目前针对木薯IIa亚族WRKY基因的系统性分析仍存在空白。本研究共鉴定得到102个WRKY家族成员，可划分为I、II、III共3个类群。瞬时表达实验显示，6个MeWRKY IIa蛋白定位于细胞核中。MeWRKY IIa基因的转录本积累水平在水杨酸（SA）、茉莉酸（JA）以及Xam处理下显著上调。在拟南芥中过表达MeWRKY27与MeWRKY33可增强其对丁香假单胞菌番茄致病变种DC3000（Pst DC3000）的抗性；与之相反，在木薯中沉默MeWRKY27与MeWRKY33则会增强植株对Xam的感病性。共表达网络分析表明，不同的MeWRKY IIa成员调控不同的下游基因。对下游基因的功能解析将为阐明木薯抗病的分子机制提供重要线索。综上，本研究结果表明，MeWRKY IIa基因受SA与JA信号通路调控，并协同参与植株对Xam侵染的响应。