保卫细胞中ABA信号调控机制研究进展

脱落酸(ABA)具有调节植物快速响应逆境的重要功能。植物细胞中ABA核心信号通路由ABA受体PYR1/PYLs/RCARs、A类碱性蛋白磷酸酶PP2Cs和Snf1相关蛋白激酶SnRK2s组成。活性氧(ROS)和Ca²⁺是保卫细胞中的重要第二信使,调控ABA诱导的气孔关闭。该文对保卫细胞中核心ABA信号蛋白的调控以及ROS和Ca²⁺介导的ABA信号转导等最新研究成果进行综述,旨在阐明保卫细胞中ABA信号调控机制。     

蛋白质可逆磷酸化对花粉管生长的调控作用

花粉管极性生长受多种信号与代谢过程的调控,主要包括Rop GTPase信号途径、磷脂酰肌醇信号通路、Ca²⁺信号途径、肌动蛋白动态变化、囊泡运输、细胞壁重塑等,这些过程都受到蛋白质可逆磷酸化作用的调节。如：(1) Rop调节蛋白(GEF、GDI和GAP)的可逆磷酸化可以改变其活性,从而调节Rop GTPase;同时,蛋白激酶还可能作为Rop下游的效应器分子参与Rop下游信号途径的调节;(2) 蛋白质可逆磷酸化作用既能够激活/失活质膜上的Ca²⁺通道或Ca²⁺泵,又参与调节胞内贮存Ca²⁺的释放,从而调控花粉管尖端Ca²⁺梯度的形成;此外,蛋白激酶还作为Ca²⁺信号的感受器,磷酸化相应的靶蛋白,参与Ca²⁺信号下游途径的调节;(3) 肌动蛋白结合蛋白(ADF和Profilin)的活性也受到蛋白质可逆磷酸化的调节,进而调控肌动蛋白聚合与解聚之间的动态平衡;(4) 蛋白质磷酸化作用调节胞吞/胞吐相关蛋白的活性,并调控质膜的磷脂代谢,从而参与调控囊泡运输过程;(5) 胞质丝氨酸/苏氨酸蛋白激酶和蔗糖合酶的可逆磷酸化可以调节其在花粉管中的功能与分布模式,参与花粉管细胞壁重塑;(6) 转录调节蛋白与真核生物翻译起始因子的可逆磷酸化可以改变其活性,从而调控RNA转录与蛋白质合成。文章主要综述了花粉管生长过程中重要蛋白质的可逆磷酸化作用对上述关键事件的调节。     

ROS信号对植物抗性的调控作用研究进展

活性氧(reactive oxygen species,ROS)是植物体代谢所产生的小分子化合物,既是生长发育和防御途径的关键调节因子,又是需氧代谢的有毒副产物。植物细胞的生理过程受一个被活性氧调节的氧化还原网状途径的调控,本文从植物体内ROS产生的部位与时空特异性、ROS信号与NO和Ca2+波信号的互作等方面综述了ROS信号对植物抗性的调控作用研究进展。     

植物与病原菌互作的分子机制研究进展

植物的先天免疫主要包括模式识别受体对保守的微生物病原相关分子模式的识别和抗病蛋白对效应蛋白的识别。植物与病原体互作过程中存在广泛的信号交流,信号分子在植物与病原体的互作攻防中发挥了重要的调控作用,决定了二者的竞争关系。当前,大量植物与病原体互作中的信号分子被定位和克隆,其作用方式被揭示。本文总结了这些信号分子及其在植物免疫过程中的作用机制,主要包括植物细胞表面的模式识别受体分子对病原相关分子模式的识别与应答,植物抗病蛋白对病原体效应蛋白的识别与应答,以及免疫反应下游相关信号分子及其在植物抗病中的作用。此外,本文对未来相关研究提出了展望。     

活性氧调控植物生长发育的研究进展

活性氧(ROS)是植物有氧代谢过程中的副产物, 它在植物的许多生命过程中均具有有害和有利的双重功能。ROS对细胞的氧化损伤作用和信号转导诱导植物防卫反应已有详尽的研究。近年来, 越来越多的关于ROS调控植物生长发育的证据开始引起了人们的广泛关注。细胞的生长是植物发育的重要部分, ROS通过直接或间接调节细胞的生长来控制植物的发育, 成为植物发育的重要调节剂。该文综述了羟自由基(.OH)及其前体超氧阴离子自由基(O2^–. )和过氧化氢(H₂O₂)调控植物生长发育的研究进展, 包括ROS调控植物不同器官生长的证据和机理、ROS产生的途径及其检测方法, 同时对今后的研究进行了展望。     

褪黑素调节烟草丁香假单胞菌抗性的功能研究

为分析褪黑素(N-乙酰-5-甲氧基色胺)在植物先天免疫中的功能及调控机理,研究以病原菌丁香假单胞杆菌(Pseudomonas syringae pv.tomato DC3000,Pst DC3000)—烟草互作系统为模型,检测了病原菌侵染对烟草褪黑素相关基因表达的影响,并探讨了褪黑素对植物叶片病原菌生长以及气孔开度和活性氧自由基(reactive oxygen species,ROS)含量的影响以及调控机理。结果表明:(1)Pst DC3000处理提高了烟草褪黑素合成(NtSNAT1)和受体(NtPMTR1)基因表达,且外源褪黑素处理降低了叶片中的病原菌含量。(2)与野生型植物相比,过表达大豆GmSNAT1基因显著提高了转基因烟草中内源褪黑素含量和NtPMTR1的表达,且转基因烟草叶片中的Pst DC3000菌落数显著下降。(3)外源褪黑素和细菌鞭毛蛋白多肽flg22处理诱导了野生型和转基因烟草保卫细胞中ROS产生和气孔关闭,且转基因植物对褪黑素和flg22诱导的气孔关闭和ROS产生比野生型烟草更加敏感。综上所述,研究表明褪黑素可能通过受体NtPMTR1介导的信号途径促进保卫细胞ROS产生,诱导气孔关闭,从而降低病原菌Pst DC3000的入侵。     

类受体激酶FER调节植物与病原菌相互作用的分子机制

植物细胞依赖细胞质膜上的受体感知并传递环境信号,而受体通过与配体特异结合启动一系列下游信号转导途径,维持植物正常的生命活动及其对外界环境变化的适应。类受体激酶是其中一类重要受体,通常由胞外结合结构域、跨膜结构域和胞内激酶结构域3部分组成,是植物适应外界环境变化的重要调节枢纽。FER属于CrRLK1L类受体蛋白激酶家族,...     

植物小分子信号肽参与非生物逆境胁迫应答的研究进展

植物小分子信号肽（small signaling peptides, SSPs）是一类蛋白长度小于120个氨基酸的小肽，作为新型信号分子在植物应答非生物逆境胁迫中发挥重要的作用。植物中含有千余种SSPs，多种多样的结构特点、修饰过程与不同受体的结合发挥其特异的功能，参与植物与环境之间的互作。挖掘鉴定植物SSPs功能基因，解析它们应答非生物逆境胁迫的调控机制，对增强植物抗性、改善植物生长具有重要的理论与实践意义。植物SSPs主要包括胞外非分泌型小肽、胞内非分泌型小肽、胞外翻译后修饰分泌型小肽和胞外富含半胱氨酸分泌型小肽四大类。介绍了四类植物SSPs的结构、特征；阐述了它们以SSP配体结合LRR-RLK受体激酶完成信号转导过程，以激活下游抗性基因表达为模式的调控机制；重点综述了它们在干旱、高温、盐渍、营养等非生物逆境胁迫应答中的生物学功能及调控机制。最后讨论了植物SSPs未来研究的方向和有待解决的问题，还对SSPs类生长调节剂的开发前景进行了展望，旨在为提高植物应对环境胁迫和实现农业可持续发展提供新的思路和路径。     

γδ+T细胞与真菌感染

近年来,随着免疫功能低下宿主数量的增加、耐药菌的多发以及新型抗真菌药物的研发进展缓慢等原因,全球真菌感染的发病率呈现逐年上升趋势,感染菌株也发生了变迁,白念珠菌的比例在逐渐减少而非白念珠菌呈上升趋势,同时耐唑类烟曲霉感染以及隐球菌病也均呈上升趋势。T细胞介导的免疫应答在抗真菌感染中占据重要地位,T细胞受体(T cell receptor, TCR)是T细胞上识别和结合抗原并介导机体免疫应答的关键分子。根据T细胞表面TCR的类型,可将T细胞分为αβ⁺T细胞和γδ⁺Τ细胞两类。随着研究的深入,γδ⁺T细胞在真菌感染中的免疫应答也逐渐被揭示,其参与过继免疫以及辅助疫苗接种的潜能逐步被挖掘。该文就γδ⁺T细胞在常见真菌感染性疾病中的作用以及其未来展望作一综述。     

植物JAZ蛋白的功能概述

茉莉酸作为重要的植物激素,在植物生长、繁殖和抗逆等诸多方面起重要的作用。茉莉酸途径的抑制因子JAZ(Jasmonate ZIM-domain,JAZ)蛋白(JAZs)是调节茉莉酸(JA)激素应答的关键因子,在没有JA存在时,JAZs抑制DNA-结合转录因子活性,从而调控JA应答基因转录;当有JA存在时,JAZs和冠菌素不敏感1(Coronatine insensitive 1,COI1)依赖JA分子发生互作,复合体被SCFCOI1识别并进入26S蛋白酶解途径降解,释放的转录因子启动JA应答基因转录。随着研究的深入,发现JAZs可以与许多转录因子互作,不仅调控了JA信号响应,还参与了其他激素信号通路。对JAZs的互作机制进行描述,阐述JAZs在植物激素调控网络中的作用。     

Cu2+对拟南芥根的局部毒性及诱导DNA损伤和细胞死亡

该文探讨了不同浓度的Cu²⁺胁迫对拟南芥(Arabidopsis thaliana)根生长、活性氧(ROS)积累、抗氧化酶活性、质膜完整性和细胞活性的影响, 通过分根实验初步分析了Cu²⁺毒性效应的影响范围。结果表明, Cu²⁺胁迫可显著抑制拟南芥主根伸长, 诱导ROS积累及DNA损伤, 促发抗氧化酶活性升高, 破坏质膜完整性, 且Cu²⁺浓度越高, 毒性效应越明显, 在高浓度Cu²⁺胁迫下细胞活性显著降低。分析各参数之间的关系, 表明ROS的积累与超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)及抗坏血酸过氧化物酶(APX)的活性呈显著正相关; ROS积累与DNA损伤、质膜完整性、细胞活性之间具有显著的近线性关系。分根实验结果表明, 只有在添加重金属Cu²⁺(75 μmol·L^–1)一侧培养基中的根生长受抑制, 并出现ROS积累、细胞死亡, 暗示Cu²⁺对拟南芥根系的局部毒性效应可能是由于ROS的局部性积累导致受胁迫根系一侧的细胞死亡所引起的。     

The RECEPTOR-LIKE PROTEIN53 immune complex associates with LLG1 to positively regulate plant immunity

Pattern recognition receptors(PRRs) sense ligands in pattern-triggered immunity(PTI). Plant PRRs include numerous receptor-like proteins(RLPs), but many RLPs remain functionally uncharacterized. Here, we examine an Arabidopsis thaliana RLP, RLP53, which positively regulates immune signaling. Our forward genetic screen for suppressors of enhanced disease resistance1(edr1) identified a point mutation in RLP53 that fully suppresses disease resistance and mildewinduced cell death in edr1 mutants. Th...     

Role of the plasma membrane ROS-generating NADPH oxidase in CD34+ progenitor cells preservation by hypoxia

Hypoxia favored the preservation of progenitor characteristics of hematopoietic stem and progenitor cells (HSPCs) in bone marrow. This work aimed at studying the role of reactive oxygen species (ROS)-generating NADPH oxidase system regulated by hypoxia in ex vivo cultures of cord blood CD34⁺ cells. The results showed that NADPH oxidase activity and ROS generation were reduced in hypoxia with respect to normal oxygen tension. Meanwhile the ROS generation was found to be inhibited by diphenyleneiodonium (the NADPH oxidase inhibitor), or N-acetylcysteine (the ROS scavenger). Accordingly NADPH oxidase mRNA and p67 protein levels decreased in hypoxia. The analysis of progenitor characteristics, including the proportion of cultured cells expressing the HSPCs marker CD34⁺CD38⁻, colony production ability of the colony-forming cells (CFCs), and the re-expansion capability of the cultured CD34⁺ cells, showed that either 5% pO₂ or reduced ROS favored preserving the characteristics of CD34⁺ progenitors, and promoted the expansion of CD34⁺CD38⁻ cells as well. The above results demonstrated that hypoxia effectively maintained biological characteristics of CD34⁺ cells through keeping lower intracellular ROS levels by regulating NADPH oxidase.     

Inter‐relationships between the heterotrimeric Gβ subunit AGB1, the receptor‐like kinase FERONIA,and RALF1 in salinity response

Plant heterotrimeric G proteins modulate numerous developmental stress responses. Recently, receptor‐like kinases (RLKs) have been implicated as functioning with G proteins and may serve as plant G‐protein‐coupled‐receptors. The RLK FERONIA (FER), in the Catharantus roseus RLK1‐like subfamily, is activated by a family of polypeptides called rapid alkalinization factors (RALFs). We previously showed that the Arabidopsis G protein β subunit, AGB1, physically interacts with FER, and that RALF1 regulation of stomatal movement through FER requires AGB1. Here, we investigated genetic interactions of AGB1 and FER in plant salinity response by comparing salt responses in the single and double mutants of agb1 and fer. We show that AGB1 and FER act additively or synergistically depending on the conditions of the NaCl treatments. We further show that the synergism likely occurs through salt‐induced ROS production. In addition, we show that RALF1 enhances salt toxicity through increasing Na⁺ accumulation and decreasing K⁺ accumulation rather than by inducing ROS production, and that the RALF1 effect on salt response occurs in an AGB1‐independent manner. Our results indicate that RLK epistatic relationships are not fixed, as AGB1 and FER display different genetic relationships to RALF1 in stomatal versus salinity responses.     

A critical review on natural compounds interacting with the plant plasma membrane H+-ATPase and their potential as biologicals in agriculture

The plant plasma membrane (PM) H⁺-ATPase is an essential enzyme controlling plant growth and development. It is an important factor in response to abiotic and biotic stresses and is subject to tight regulation. We are in demand for new sustainable natural growth regulators and as a key enzyme for regulation of transport into the plant cell the PM H⁺-ATPase is a potential target for these. In this review, we have evaluated the known non-protein natural compounds with regulatory effects on the PM H⁺-ATPase, focusing on their mechanism of action and their potential as biologicals/growth regulators in plant production of future sustainable agriculture.     

The Arabidopsis phosphatase PP2C49 negatively regulates salt tolerance through inhibition of AtHKT1;1

Type 2C protein phosphatases (PP2Cs) are the largest protein phosphatase family. PP2Cs dephosphorylate substrates for signaling in Arabidopsis, but the functions of most PP2Cs remain unknown. Here, we characterized PP2C49 (AT3G62260, a Group G PP2C), which regulates Na⁺ distribution under salt stress and is localized to the cytoplasm and nucleus. PP2C49 was highly expressed in root vascular tissues and its disruption enhanced plant tolerance to salt stress. Compared with wild type, the pp2c49 mutant contained more Na⁺ in roots but less Na⁺ in shoots and xylem sap, suggesting that PP2C49 regulates shoot Na⁺ extrusion. Reciprocal grafting revealed a root‐based mechanism underlying the salt tolerance of pp2c49. Systemic Na⁺ distribution largely depends on AtHKT1;1 and loss of function of AtHKT1;1 in the pp2c49 background overrode the salt tolerance of pp2c49, resulting in salt sensitivity. Furthermore, compared with plants overexpressing PP2C49 in the wild‐type background, plants overexpressing PP2C49 in the athtk1;1 mutant background were sensitive to salt, like the athtk1;1 mutants. Moreover, protein–protein interaction and two‐voltage clamping assays demonstrated that PP2C49 physically interacts with AtHKT1;1 and inhibits the Na⁺ permeability of AtHKT1;1. This study reveals that PP2C49 negatively regulates AtHKT1;1 activity and thus determines systemic Na⁺ allocation during salt stress.     

OsDRE2 contributes to chitin-triggered response through its interaction with OsRLCK185

The rice receptor-like cytoplasmic kinase 185 (OsRLCK185) interacts with the chitin receptor complex OsCERK1/CEBiP and positively regulates chitin-induced immune responses including MAP kinase activation, ROS production and defense gene expression. To elucidate the regulatory mechanisms of OsRLCK185-mediated immunity, we searched for interactors of OsRLCK185. OsDRE2a, rice homologs of the yeast Dre2 protein, were identified as novel interactors of OsRLCK185. OsDRE2a interacted with OsRLCK185 at plasma membrane. The conserved cysteine residues in CIAPIN1 domain of OsDRE2a were essential for tight interaction of OsRLCK185. OsDRE2a was phosphorylated by OsRLCK185. The expression of OsDRE2a and OsDRE2b was induced after chitin treatment. Reduction of OsDRE2a and OsDRE2b mRNA levels by RNA interference resulted in the decreased chitin-induced ROS production. Thus, it is likely that OsDRE2 regulates OsRLCK185-mediated immune responses.     

FERONIA is involved in phototropin 1-mediated blue light phototropic growth in Arabidopsis

Plant shoot phototropism is triggered by the formation of a light-driven auxin gradient leading to bending growth. The blue light receptor phototropin 1(phot1) senses light direction, but how this leads to auxin gradient formation and growth regulation remains poorly understood. Previous studies have suggested phot1’s role for regulated apoplastic acidification, but its relation to phototropin and hypocotyl phototropism is unclear. Herein, we show that blue light can cause phot1 to interact with...