今天介紹的是新發表在《Plant Physiology》上的研究論文，由山東大學侯丙凱團隊發表的題為《Methyl salicylate glucosylation regulates plant defense signalling and systemic acquired resistance》的論文。
植物系統獲得性抗性（SAR）為病原體提供有效的廣譜免疫應答。SAR涉及由受感染組織產生並轉運至全身組織的移動信號分子。水楊酸甲酯（MeSA）是一種可轉化為水楊酸（SA）的分子，是建立SAR的重要信號，特別是在病原體感染後短時間暴露於光線下。因此，MeSA穩態的控制對於SAR最佳的響應是重要的。
在本文中，作者在擬南芥中克隆了尿苷二磷酸 - 糖基轉移酶UGT71C3，其主要在葉組織中被病原體（Pst DC3000/avrRpt2）誘導。生化分析表明，UGT71C3在體外和體內對MeSA表現出強的酶活性，形成MeSA葡萄糖苷。
在通過Pst DC3000 / avrRpt2感染原發病原體後，ugt71c3敲除突變體對次級病原體感染表現出比野生型（WT）植物更強的系統抗性，而UGT71C3過表達株系中的系統抗性受到損害。
一致的是，在局部葉片的原發感染後，ugt71c3敲除突變體比WT植物中積累的MeSA和SA顯著更多，而UGT71C3過表達株系積累更少。
作者的結果表明，UGT71C3的MeSA糖基化通過調節MeSA和SA的體內平衡促進SAR反應的負調節。該研究揭示了進一步的SAR調節機制，並強調了MeSA的葡糖基化作用以及潛在的其他系統信號在負調節植物系統防禦中的作用。
Plant systemic acquired resistance (SAR) provides an efficient broad-spectrum immune response to pathogens. SAR involves mobile signal molecules that are generated by infected tissues and transported to systemic tissues. Methyl salicylate (MeSA), a molecule that can be converted to salicylic acid (SA), is an essential signal for establishing SAR, particularly under a short period of exposure to light after pathogen infection. Thus, the control of MeSA homeostasis is important for an optimal SAR response. Here, we characterized a uridine diphosphate-glycosyltransferase, UGT71C3, in Arabidopsis thaliana, which was induced mainly in leaf tissue by pathogens including Pst DC3000/avrRpt2 (Pseudomonas syringae pv. tomato strain DC3000 expressing avrRpt2). Biochemical analysis indicated that UGT71C3 exhibited strong enzymatic activity towards MeSA to form MeSA glucosides in vitro and in vivo. Following primary pathogen infection by Pst DC3000/avrRpt2, ugt71c3 knockout mutants exhibited more powerful systemic resistance to secondary pathogen infection than that of wild-type (WT) plants, whereas systemic resistance in UGT71C3 overexpression lines was compromised. In agreement, following primary infection of local leaves, ugt71c3 knockout mutants accumulated significantly more systemic MeSA and SA than that in WT plants whereas UGT71C3 overexpression lines accumulated less. Our results suggest that MeSA glucosylation by UGT71C3 facilitates negative regulation of the SAR response by modulating homeostasis of MeSA and SA. This study unveils further SAR regulation mechanisms and highlights the role of glucosylation of MeSA and potentially other systemic signals in negatively modulating plant systemic defense.
今天就策到這裡，點擊閱讀原文可以查看原文。
"植物病毒與抗逆研究"由浙江大學植物病理學博士研究生黑暗大邪神管理與運營。
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