CAMTA-Mediated Regulation of Salicylic Acid Immunity Pathway Genes in Arabidopsis Exposed to Low Temperature and Pathogen Infection
CAMTA-Mediated Regulation of Salicylic Acid Immunity Pathway Genes in Arabidopsis Exposed to Low Temperature and Pathogen Infection
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DOI：
10.1105/tpc.16.00865
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发表时间：
2017-10-01
期刊：
影响因子：
11.6
通讯作者：
Thomashow, Michael F.
中科院分区：
文献类型：
--
作者：
Kim, Yong Sig;An, Chuanfu;Thomashow, Michael F.
拟南芥钙调素结合转录激活子(CAMTA)因子抑制生长在22℃下的健康植物中水杨酸(SA)生物合成和SA介导的免疫相关基因的表达。这种抑制在暴露于低温(4摄氏度)一周以上的植物中被克服，在被生物营养和半生物营养病原体感染的植物中被克服。在这里，我们提供的证据表明，CAMTA3介导的非胁迫植物SA途径基因的抑制涉及一个N末端抑制模块(NRM)的作用，该模块独立于钙调蛋白(CaM)与IQ和CaM结合(Camb)结构域的结合，这一发现与目前认为CAMTA3抑制活性需要CaM与Camb结构域结合的想法相反。在只表达蛋白质的CAMTA3-NRM区域的植物中，没有发生对低温响应的SA途径基因的诱导。突变分析提供的证据表明，NRM的抑制活性是由于IQ和Camb结构域对低温反应产生的信号的反应而受到抑制。表达CAMTA3-NRM区域的植株对细菌半生物营养病原菌紫丁香假单胞菌番茄DC3000的防御能力也受到了损害。我们的结果表明，低温和病原菌侵染对CAMTA3抑制活性的调节涉及到相关的机制，但存在明显的差异。
Arabidopsis thaliana calmodulin binding transcription activator (CAMTA) factors repress the expression of genes involved in salicylic acid (SA) biosynthesis and SA-mediated immunity in healthy plants grown at warm temperature (22 degrees C). This repression is overcome in plants exposed to low temperature (4 degrees C) for more than a week and in plants infected by biotrophic and hemibiotrophic pathogens. Here, we present evidence that CAMTA3-mediated repression of SA pathway genes in nonstressed plants involves the action of an N-terminal repression module (NRM) that acts independently of calmodulin (CaM) binding to the IQ and CaM binding (CaMB) domains, a finding that is contrary to current thinking that CAMTA3 repression activity requires binding of CaM to the CaMB domain. Induction of SA pathway genes in response to low temperature did not occur in plants expressing only the CAMTA3-NRM region of the protein. Mutational analysis provided evidence that the repression activity of the NRM was suppressed by action of the IQ and CaMB domains responding to signals generated in response to low temperature. Plants expressing the CAMTA3-NRM region were also impaired in defense against the bacterial hemibiotrophic pathogen Pseudomonas syringae pv tomato DC3000. Our results indicate that the regulation of CAMTA3 repression activity by low temperature and pathogen infection involves related mechanisms, but with distinct differences.