A Plant Phytosulfokine Peptide Initiates Auxin-Dependent Immunity through Cytosolic Ca2+ Signaling in Tomato 

First author: Huan Zhang; Affiliations: Zhejiang University (浙江大学): Zhejiang, China

Corresponding author: Kai Shi (师恺)

Phytosulfokine (PSK; 磺肽素) is a disulfated (硫酸化) pentapeptide (五肽) that is an important signaling molecule. Although it has recently been implicated (牵涉其中的) in plant defenses to pathogen infection, the mechanisms involved remain poorly understood. Using surface plasmon resonance (表面等离子体共振) and gene silencing approaches, we showed that the tomato (Solanum lycopersicum, Sl) PSK receptor PSKR1, rather than PSKR2, functioned as the major PSK receptor in immune responses. Silencing of PSK signaling genes rendered (提供) tomato more susceptible to infection by the economically-important necrotrophic (死体营养的) pathogen Botrytis cinerea (灰霉病). Analysis of tomato mutants defective in either defense hormone biosynthesis or signaling demonstrated that PSK-induced immunity required auxin biosynthesis and associated defense pathways. Using aequorin-expressing (发光蛋白) tomato plants, we here provide evidence that PSK perception by tomato PSKR1 elevated cytosolic [Ca2+], leading to auxin-dependent immune responses via enhanced binding activity between CaMs and the auxin biosynthetic YUCs. Thus, our data demonstrate that PSK acts as a damage-associated molecular pattern and is perceived mainly by PSKR1, which increases cytosolic [Ca2+] and activates auxin-mediated pathways that enhance immunity of tomato plants to B. cinerea.

磺肽素PSK是硫酸化的五肽，是一个重要的信号分子。尽管已有研究显示PSK参与植物对于病原菌侵染的抗性，然而背后的分子机制还不清楚。利用表面等离子体共振和基因沉默的方法，作者的研究显示番茄PSK受体PSKR1要比PSKR2更加在免疫响应中作为主要的PSK受体。对PSK信号转导基因的沉默使得番茄更加容易被死体营养的灰霉病侵染。通过对抗性激素生物合成或信号转导缺陷的番茄突变体的分析显示PSK诱导的免疫需要生长素生物合成和相关的防御通路。利用表达发光蛋白的番茄植株，作者显示番茄PSKR1对于PSK的感知会提升胞质中Ca2+浓度，进而通过增强CaMs和生长素生物合成YUCs之间的结合活性增加生长素依赖的免疫响应。因此，本研究显示PSK作为一个伤害相关的分子模式，主要由PSKR1来感知PSK，通过增加胞质中的Ca2+浓度和激活生长素介导的通路来增加番茄对于灰霉病的免疫。

通讯：师恺 (http://www.cab.zju.edu.cn/ivs/2017/0330/c7881a492202/page.htm)

个人简介：1998-2002年，河南农业大学园艺系，学士；2002-2007年，浙江大学园艺系，博士；2007- 2009年，浙江大学生物学，博士后；2012-2013年，美国康奈尔大学，访问学者。

研究方向：番茄免疫机制及调控；设施环境—番茄作物—病原生物互作机制及调控。

doi: https://doi.org/10.1105/tpc.17.00537

Journal: Plant Cell

First Published date: 06 March, 2018

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