An RXLR effector PlAvh142 from Peronophythora litchii triggers plant cell death and contributes to virulence
An RXLR effector PlAvh142 from Peronophythora litchii triggers plant cell death and contributes to virulence
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荔枝霜霉的 RXLR 效应子 PlAvh142 触发植物细胞死亡并增强毒力
DOI：
10.1111/mpp.12905
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发表时间：
2020-01-07
影响因子：
4.9
通讯作者：
Jiang, Zide
中科院分区：
文献类型：
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作者：
Situ, Junjian;Jiang, Liqun;Jiang, Zide
摘要荔枝青枯病是由荔枝疫霉（Peronophythora litchii）引起的一种植物病害，每年给荔枝生产造成巨大的经济损失。为了成功地定植宿主细胞，疫霉菌会分泌数百种干扰植物免疫并促进感染过程的RXLR效应物。先前的研究已经预测了荔枝中245个候选RXLR效应编码基因，其中212个基因已被克隆并在本研究中进行了植物细胞死亡诱导活性测试。我们发现三种RXLR效应物可以通过在烟叶中的瞬时表达触发植物细胞死亡。进一步的实验表明，PlAvh142可以诱导多种植物的细胞死亡和免疫反应。我们还发现PlAvh142定位于植物细胞的细胞质和细胞核中。细胞质定位是其诱导细胞死亡活性的关键。此外，删除PlAvh142中两个内部重复序列中的任何一个都可以消除细胞诱导死亡的活性。病毒诱导的基因沉默实验表明，PlAvh142引发的细胞死亡依赖于植物转导成分RAR1 （Mla12抗性所需）、SGT1 （skp1的G2等位基因抑制因子）和HSP90（热休克蛋白90）。最后，敲除PlAvh142可显著降低荔枝假体对荔枝植株的毒力，而过表达PlAvh142的突变体更具侵袭性。这些数据表明，PlAvh142在植物细胞质中可以被识别，是荔枝RXLR的重要毒力效应因子。
Abstract Litchi downy blight, caused by the phytopathogenic oomycete Peronophythora litchii, results in tremendous economic loss in litchi production every year. To successfully colonize the host cell, Phytophthora species secret hundreds of RXLR effectors that interfere with plant immunity and facilitate the infection process. Previous work has already predicted 245 candidate RXLR effector‐encoding genes in P. litchii, 212 of which have been cloned and tested for plant cell death‐inducing activity in this study. We found three such RXLR effectors could trigger plant cell death through transient expression in Nicotiana benthamiana. Further experiments demonstrated that PlAvh142 could induce cell death and immune responses in several plants. We also found that PlAvh142 localized in both the cytoplasm and nucleus of plant cells. The cytoplasmic localization was critical for its cell death‐inducing activity. Moreover, deletion either of the two internal repeats in PlAvh142 abolished the cell death‐inducing activity. Virus‐induced gene silencing assays showed that cell death triggered by PlAvh142 was dependent on the plant transduction components RAR1 (require for Mla12 resistance), SGT1 (suppressor of the G2 allele of skp1) and HSP90 (heat shock protein 90). Finally, knockout of PlAvh142 resulted in significantly attenuated P. litchii virulence on litchi plants, whereas the PlAvh142‐overexpressed mutants were more aggressive. These data indicated that PlAvh142 could be recognized in plant cytoplasm and is an important virulence RXLR effector of P. litchii.