Peng Hsuan-Chieh, Kaloshian Isgouhi
Department of Nematology, Graduate Program in Botany and Plant Sciences, Center for Plant Cell Biology, University of California Riverside, Riverside, California, United States of America.
PLoS One. 2014 Mar 27;9(3):e93302. doi: 10.1371/journal.pone.0093302. eCollection 2014.
The Somatic Embryogenesis Receptor Kinase 3 (SERK3)/Brassinosteroid (BR) Insensitive 1-Associated Kinase 1 (BAK1) is required for pattern-triggered immunity (PTI) in Arabidopsis thaliana and Nicotiana benthamiana. Tomato (Solanum lycopersicum) has three SlSERK members. Two of them exhibit particularly high levels of sequence similarity to AtSERK3 and, therefore, were named SlSERK3A and SlSERK3B. To characterize a role for SlSERK3A and SlSERK3B in defense, we suppressed each gene individually or co-silenced both using virus-induced gene silencing (VIGS) in the tomato cv. Moneymaker. Co-silencing SlSERK3A and SlSERK3B resulted in spontaneous necrotic lesions and reduced sensitivity to exogenous BR treatment. Silencing either SlSERK3A or SlSERK3B resulted in enhanced susceptibility to root knot-nematode and to non-pathogenic Pseudomonas syringae pv. tomato (Pst) DC3000 hrcC indicating that both SlSERK3s are positive regulators of defense. Interestingly, silencing SlSERK3B, but not SlSERK3A, resulted in enhanced susceptibility to the pathogenic strain Pst DC3000 indicating distinct roles for these two SlSERK3 paralogs. SlSERK3A and SlSERK3B are active kinases, localized to the plasma membrane, and interact in vivo with the Flagellin Sensing 2 receptor in a flg22-dependent manner. Complementation of the Atserk3/bak1-4 mutant with either SlSERK3A or SlSERK3B partially rescued the mutant phenotype. Thus, SlSERK3A and SlSERK3B are likely to constitute tomato orthologs of BAK1.
体细胞胚胎发生受体激酶3（SERK3）/油菜素类固醇（BR）不敏感1相关激酶1（BAK1）是拟南芥和本氏烟草中模式触发免疫（PTI）所必需的。番茄（Solanum lycopersicum）有三个SlSERK成员。其中两个与AtSERK3表现出特别高的序列相似性，因此被命名为SlSERK3A和SlSERK3B。为了表征SlSERK3A和SlSERK3B在防御中的作用，我们在番茄品种Money maker中使用病毒诱导基因沉默（VIGS）分别抑制每个基因或同时共沉默这两个基因。共沉默SlSERK3A和SlSERK3B导致自发坏死病变，并降低对外源BR处理的敏感性。沉默SlSERK3A或SlSERK3B导致对根结线虫和非致病性丁香假单胞菌番茄致病变种（Pst）DC3000 hrcC的易感性增强，表明这两个SlSERK3都是防御的正调控因子。有趣的是，沉默SlSERK3B而不是SlSERK3A导致对致病菌株Pst DC3000的易感性增强，表明这两个SlSERK3旁系同源物具有不同的作用。SlSERK3A和SlSERK3B是活性激酶，定位于质膜，并在体内以flg22依赖的方式与鞭毛蛋白传感2受体相互作用。用SlSERK3A或SlSERK3B对Atserk3/bak1-4突变体进行互补部分挽救了突变体表型。因此，SlSERK3A和SlSERK3B可能构成BAK1的番茄直系同源物。
