AP2/ERF转录因子调控植物非生物胁迫响应研究进展

低温、干旱、高盐和缺氧等多种不良环境影响植物的生长发育, 植物通过长期进化形成复杂的调节机制来适应这些不利条件。AP2/ERF是植物特有的转录因子, 在各种胁迫响应过程中发挥关键调控作用。近年来, 越来越多的研究表明, 植物激素介导的信号级联通路与逆境胁迫响应关系密切, AP2/ERF转录因子可与激素信号转导协同形成交叉调控网络。许多AP2/ERF转录因子通过响应植物激素脱落酸和乙烯, 激活依赖或不依赖于脱落酸和乙烯的胁迫响应基因的表达。此外, AP2/ERF转录因子参与赤霉素、细胞分裂素和油菜素内酯介导的生长发育和胁迫应答。该文简要综述了AP2/ERF转录因子的结构特征、转录调控、翻译后修饰、结合位点、协同互作蛋白及其参与调控依赖或不依赖激素信号转导途径的非生物胁迫响应研究进展, 为解析不同AP2/ERF转录因子在调控激素和胁迫响应网络中的作用提供理论依据。     

A Role for Arabidopsis miR399f in Salt,Drought, and ABA Signaling

MiR399f plays a crucial role in maintaining phosphate homeostasis in Arabidopsis thaliana. Under phosphate starvation conditions, AtMYB2, which plays a role in plant salt and drought stress responses, directly regulates the expression of miR399f. In this study, we found that miR399f also participates in plant responses to abscisic acid (ABA), and to abiotic stresses including salt and drought. Salt and ABA treatment induced the expression of miR399f, as confirmed by histochemical analysis of promoter-GUS fusions. Transgenic Arabidopsis plants overexpressing miR399f (miR399f-OE) exhibited enhanced tolerance to salt stress and exogenous ABA, but hypersensitivity to drought. Our in silico analysis identified ABF3 and CSP41b as putative target genes of miR399f, and expression analysis revealed that mRNA levels of ABF3 and CSP41b decreased remarkably in miR399f-OE plants under salt stress and in response to treatment with ABA. Moreover, we showed that activation of stress-responsive gene expression in response to salt stress and ABA treatment was impaired in miR399f-OE plants. Thus, these results suggested that in addition to phosphate starvation signaling, miR399f might also modulates plant responses to salt, ABA, and drought, by regulating the expression of newly discovered target genes such as ABF3 and CSP41b.     

Calmodulin-like protein CML37 is a positive regulator of ABA during drought stress in Arabidopsis

Plants need to adapt to various stress factors originating from the environment. Signal transduction pathways connecting the recognition of environmental cues and the initiation of appropriate downstream responses in plants often involve intracellular Ca²⁺ concentration changes. These changes must be deciphered into specific cellular signals. Calmodulin-like proteins, CMLs, act as Ca²⁺ sensors in plants and are known to be involved in various stress reactions. Here, we show that in Arabidopsis 2 different CMLs, AtCML37 and AtCML42 are antagonistically involved in drought stress response. Whereas a CML37 knock-out line, cml37, was highly susceptible to drought stress, CML42 knockout line, cml42, showed no obvious effect compared to wild type (WT) plants. Accordingly, the analysis of the phytohormone abscisic acid (ABA) revealed a significant reduction of ABA upon drought stress in cml37 plants, while in cml42 plants an increase of ABA was detected. Summarizing, our results show that both CML37 and CML42 are involved in drought stress response but show antagonistic effects.     

Identification and functional roles of CaDIN1 in abscisic acid signaling and drought sensitivity

Plants frequently face challenges caused by various abiotic stresses, including drought, and have evolved defense mechanisms to counteract the deleterious effects of these stresses. The phytohormone abscisic acid (ABA) is involved in signal transduction pathways that mediate defense responses of plants to abiotic stress. Here, we report a new function of the CaDIN1 protein in defense responses to abiotic stress. The CaDIN1 gene was strongly induced in pepper leaves exposed to ABA, NaCl, and drought stresses. CaDIN1 proteins share high sequence homology with other known DIN1 proteins and are localized in chloroplasts. We generated CaDIN1-silenced peppers and overexpressing transgenic Arabidopsis plants and evaluated their response to ABA and drought stress. Virus-induced gene silencing of CaDIN1 in pepper plants conferred enhanced tolerance to drought stress, which was accompanied by low levels of lipid peroxidation in dehydrated leaves. CaDIN1-overexpressing transgenic plants exhibited reduced sensitivity to ABA during seed germination and seedling stages. Transgenic plants were more vulnerable to drought than that by the wild-type plants because of decreased expression of ABA responsive stress-related genes and reduced stomatal closure in response to ABA. Together, these results suggest that CaDIN1 modulates drought sensitivity through ABA-mediated cell signaling.     

Plant stress surveillance monitored by ABA and disease signaling interactions

Abiotic and biotic stresses are the major factors that negatively impact plant growth. In response to abiotic environmental stresses such as drought, plants generate resistance responses through abscisic acid (ABA) signal transduction. In addition to the major role of ABA in abiotic stress signaling, ABA signaling was reported to downregulate biotic stress signaling. Conversely recent findings provide evidence that initial activation of plant immune signaling inhibits subsequent ABA signal transduction. Stimulation of effector-triggered disease response can interfere with ABA signal transduction via modulation of internal calcium-dependent signaling pathways. This review overviews the interactions of abiotic and biotic stress signal transduction and the mechanism through which stress surveillance system operates to generate the most efficient resistant traits against various stress condition.     

谷子bZIP转录因子的全基因组鉴定及其在干旱和盐胁迫下的表达分析

bZIP蛋白是植物转录因子中最大和最保守的一类转录因子, 参与调控植物生长发育等多种生命活动。谷子(Setaria italica)是一种重要的C4杂粮作物, 其bZIP基因家族与功能报道较少。利用生物信息学工具, 从谷子全基因组中鉴定出73个SibZIP转录因子, 划分为A、B、C、D、E、G、H、I和X等亚家族。与已测序的禾谷类作物相比, 谷子SibZIP基因家族在进化中发生缩减。在谷子SibZIP蛋白中检测到25种不同的保守氨基酸基序。RNA-seq和定量PCR检测结果表明, 在干旱和盐胁迫条件下, 多数SibZIPs基因不同程度地被诱导表达, 预示着部分SibZIP成员在谷子干旱和盐胁迫响应中起重要作用。共表达关联性分析进一步揭示19个谷子SibZIP转录因子可通过与蛋白激酶或NPR1相关调节蛋白等互作介导谷子胁迫响应。研究结果为全面解析谷子SibZIPs基因结构与生物学功能、抗旱分子机制以及分子育种提供了新信息。