Multiple candidate effectors from the oomycete pathogen Hyaloperonospora arabidopsidis suppress host plant immunity.
Multiple candidate effectors from the oomycete pathogen Hyaloperonospora arabidopsidis suppress host plant immunity.
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DOI：
10.1371/journal.ppat.1002348
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发表时间：
2011-11
期刊：
影响因子：
6.7
通讯作者：
Jones JD
中科院分区：
文献类型：
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作者：
Fabro G;Steinbrenner J;Coates M;Ishaque N;Baxter L;Studholme DJ;Körner E;Allen RL;Piquerez SJ;Rougon-Cardoso A;Greenshields D;Lei R;Badel JL;Caillaud MC;Sohn KH;Van den Ackerveken G;Parker JE;Beynon J;Jones JD
卵菌病原体引起多种植物病害。为了成功地定殖它们的宿主，它们提供了一套可以削弱植物防御的效应蛋白。在卵菌纲绒毛霉菌中，效应子携带信号肽和RxLR基序。透明霜霉（Hyaloperonospora arabidopsidis，Hpa）在模式植物拟南芥（Arabidopsis thaliana，Arabidopsis）上引起霜霉病。我们研究了Hpa分离物Hacy 2（HaRxLs）的基因组序列中预测的候选效应子是否能够操纵不同拟南芥种质中的宿主防御。我们开发了一种快速和灵敏的筛选方法来测试HaRxLs，通过将它们通过细菌型3分泌系统（TTSS）的假单胞菌番茄致病变种DC 3000-LUX（Pst-LUX）和评估的变化，Pst-LUX生长在植物上的12个拟南芥种质。测试的64个候选物中的大多数（约70%）对Pst-LUX在多于一个加入物上的生长有积极贡献，表明Hpa毒力可能涉及具有弱加入物特异性效应的多个效应物。用Pst突变体（ΔCEL）进行的进一步筛选显示，允许增强的Pst-LUX生长的HaRxL通常抑制胼胝质沉积，这是病原体相关分子模式（PAMP）触发的免疫（PTI）的标志。我们发现HaRxLs很少是强无毒决定子。虽然有些下降Pst-LUX增长在特定的加入，没有激活宏观细胞死亡。较少的HaRxLs赋予增强的Pst生长在芜菁上，芜菁是Hpa的非宿主，而几个降低了它，这与芜菁对Hpa的非宿主抗性可能涉及公认的HaRxLs和无效的HaRxLs的组合的想法一致。我们通过在拟南芥中组成型表达HaRxLs的一个子集来验证我们的结果。几个转基因株系显示出对Hpa的敏感性增加和拟南芥PTI反应的减弱，证实了HaRxLs在Hpa毒力中的作用。本研究表明，TTSS筛选系统提供了一个有用的工具，以测试是否候选效应子从真核病原体可以抑制/触发植物防御机制，并排名其有效性之前，随后的机制调查。 阿拉伯透明霜霉（Hyaloperonospora arabidopsidis，Hpa）是一种专性生物营养菌，其种群与其宿主拟南芥（Arabidopthaliana）共同进化。Hpa分离株p53 y2基因组已被测序，允许发现数十个分泌的候选效应子。我们开始为这些候选效应子分配功能，调查它们是否抑制宿主防御。我们分析了一个子集的Hpa候选效应（HaRxLs）进行RxLR基序，使用细菌系统在植物交付。令我们惊讶的是，我们发现大多数HaRxLs增强植物的易感性至少在一些accessions. These表型主要是证实拟南芥转基因株系稳定表达HaRxLs，变得更容易兼容Hpa分离物。此外，赋予增强的毒力的效应子通常抑制胼胝质沉积，这是植物防御的标志。这表明Hpa的“效应子组”包含多种不同的效应子，其可以减弱拟南芥属的免疫力。我们发现，许多HaRxLs并没有赋予增强的毒力对所有的主机加入，也只有约50%的效应，赋予增强的Pst生长拟南芥，能够这样做的芜菁，一个非主机的Hpa。我们的数据揭示了有趣的HaRxLs在未来的实验中进行详细的机制研究。
Oomycete pathogens cause diverse plant diseases. To successfully colonize their hosts, they deliver a suite of effector proteins that can attenuate plant defenses. In the oomycete downy mildews, effectors carry a signal peptide and an RxLR motif. Hyaloperonospora arabidopsidis (Hpa) causes downy mildew on the model plant Arabidopsis thaliana (Arabidopsis). We investigated if candidate effectors predicted in the genome sequence of Hpa isolate Emoy2 (HaRxLs) were able to manipulate host defenses in different Arabidopsis accessions. We developed a rapid and sensitive screening method to test HaRxLs by delivering them via the bacterial type-three secretion system (TTSS) of Pseudomonas syringae pv tomato DC3000-LUX (Pst-LUX) and assessing changes in Pst-LUX growth in planta on 12 Arabidopsis accessions. The majority (∼70%) of the 64 candidates tested positively contributed to Pst-LUX growth on more than one accession indicating that Hpa virulence likely involves multiple effectors with weak accession-specific effects. Further screening with a Pst mutant (ΔCEL) showed that HaRxLs that allow enhanced Pst-LUX growth usually suppress callose deposition, a hallmark of pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). We found that HaRxLs are rarely strong avirulence determinants. Although some decreased Pst-LUX growth in particular accessions, none activated macroscopic cell death. Fewer HaRxLs conferred enhanced Pst growth on turnip, a non-host for Hpa, while several reduced it, consistent with the idea that turnip's non-host resistance against Hpa could involve a combination of recognized HaRxLs and ineffective HaRxLs. We verified our results by constitutively expressing in Arabidopsis a sub-set of HaRxLs. Several transgenic lines showed increased susceptibility to Hpa and attenuation of Arabidopsis PTI responses, confirming the HaRxLs' role in Hpa virulence. This study shows TTSS screening system provides a useful tool to test whether candidate effectors from eukaryotic pathogens can suppress/trigger plant defense mechanisms and to rank their effectiveness prior to subsequent mechanistic investigation. Hyaloperonospora arabidopsidis (Hpa) is an obligate biotroph whose population coevolves with its host, Arabidopsis thaliana. The Hpa isolate Emoy2 genome has been sequenced, allowing the discovery of dozens of secreted candidate effectors. We set out to assign functions to these candidate effectors, investigating if they suppress host defenses. We analyzed a sub-set of Hpa candidate effectors (HaRxLs) that carry the RxLR motif, using a bacterial system for in planta delivery. To our surprise, we found that most of the HaRxLs enhanced plant susceptibility on at least some accessions, while few decreased it. These phenotypes were mostly confirmed on Arabidopsis transgenic lines stably expressing HaRxLs that became more susceptible to compatible Hpa isolates. Furthermore, effectors that conferred enhanced virulence generally suppressed callose deposition, a hallmark of plant defense. This indicates that the “effectorome” of Hpa comprises multiple distinct effectors that can attenuate Arabidopsis immunity. We found that many HaRxLs did not confer enhanced virulence on all host accessions, and also that only ∼50% of the effectors that conferred enhanced Pst growth on Arabidopsis, were able to do so on turnip, a non-host for Hpa. Our data reveal interesting HaRxLs for detailed mechanistic investigation in future experiments.
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影响因子：
4.3
作者：
Dong, Xiaoyun;Hong, Zonglie;Verma, Desh Pal S.
通讯作者：
Verma, Desh Pal S.
影响因子：
64.5
作者：
Axtell, MJ;Staskawicz, BJ
通讯作者：
Staskawicz, BJ
影响因子：
11.6
作者：
Dou, Daolong;Kale, Shiv D.;Tyler, Brett M.
通讯作者：
Tyler, Brett M.
影响因子：
64.8
作者：
Fu, Zheng Qing;Guo, Ming;Alfano, James R.
通讯作者：
Alfano, James R.
DOI：
10.1126/science.1171647
发表时间：
2009-05-08
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Boller T;He SY
通讯作者：
He SY