College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang Province, 321004, China.
College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang Province, 321004, China.
Plant Sci. 2020 Mar;292:110386. doi: 10.1016/j.plantsci.2019.110386. Epub 2019 Dec 24.
The plasma membrane (PM)-localized receptor-like kinases (RLKs) play important roles in pathogen defense. One of the first cloned RLKs is the Arabidopsis receptor kinase FLAGELLIN SENSING 2 (FLS2), which specifically recognizes a conserved 22 amino acid N-terminal sequence of Pseudomonas syringae pv．tomato DC3000 (Pst) flagellin protein (flg22). Although extensively studied in Arabidopsis, the functions of RLKs in crop plants remain largely uninvestigated. To understand the roles of RLKs in soybean (Glycine max), GmFLS2 was silenced via virus induced gene silencing (VIGS) mediated by Bean pod mottle virus (BPMV). No significant morphological differences were observed between GmFLS2-silenced plants and the vector control plants. However, silencing GmFLS2 significantly enhanced the susceptibility of the soybean plants to Pseudomonas syringae pv．glycinea (Psg). Kinase activity assay showed that silencing GmFLS2 significantly reduced the phosphorylation level of GmMPK6 in response to flg22 treatment. However, reduced phosphorylation level of both GmMPK3 and GmMPK6 in response to Psg infection was observed in GmFLS2-silenced plants, implying that defense response is likely transduced through activation of the downstream GmMAPK signaling pathway upon recognition of bacterial pathogen by GmFLS2. The core peptides of flg22 from Pst and Psg were highly conserved and only 4 amino acid differences were seen at their N-termini. Interestingly, it appeared that the Psg-flg22 was more effective in activating soybean MAPKs than activating Arabidopsis MAPKs, and conversely, Pst-flg22 was more effective in activating Arabidopsis MAPKs than activating soybean MAPKs, suggesting that the cognate recognition is more potent than heterologous recognition in activating downstream signaling. Taken together, our results suggest that the function of FLS2 is conserved in immunity against bacteria pathogens across different plant species.
质膜（PM）定位的受体样激酶（RLKs）在病原体防御中发挥重要作用。第一个被克隆的 RLK 是拟南芥受体激酶 FLAGELLIN SENSING 2（FLS2），它特异性识别丁香假单胞菌 pv.番茄 DC3000（Pst）鞭毛蛋白（flg22）的保守 22 个氨基酸 N 端序列。尽管在拟南芥中进行了广泛研究，但 RLKs 在作物植物中的功能仍在很大程度上未被研究。为了了解大豆（Glycine max）中 RLKs 的作用，通过 Bean pod mottle virus（BPMV）介导的病毒诱导基因沉默（VIGS）沉默 GmFLS2。在 GmFLS2 沉默植物和载体对照植物之间未观察到明显的形态差异。然而，沉默 GmFLS2 显著增强了大豆植物对丁香假单胞菌 pv.大豆（Psg）的易感性。激酶活性测定表明，沉默 GmFLS2 显著降低了 flg22 处理后 GmMPK6 的磷酸化水平。然而，在 GmFLS2 沉默植物中观察到 GmMPK3 和 GmMPK6 对 Psg 感染的磷酸化水平降低，这表明防御反应可能通过 GmFLS2 识别细菌病原体后下游 GmMAPK 信号通路的激活来传递。Pst 和 Psg 的 flg22 的核心肽高度保守，仅在其 N 端有 4 个氨基酸差异。有趣的是，似乎 Psg-flg22 比激活拟南芥 MAPKs 更有效地激活大豆 MAPKs，反之，Pst-flg22 比激活大豆 MAPKs 更有效地激活拟南芥 MAPKs，这表明同源识别比异源识别更有效地激活下游信号。总之，我们的结果表明，FLS2 的功能在不同植物物种的细菌病原体免疫中是保守的。
