褪黑素参与植物抗逆功能研究进展

褪黑素(N-乙酰基-5-甲氧基色胺)是一种生命必需的小分子吲哚胺类物质, 广泛存在于动植物体内, 对动植物的生长发育起至关重要的作用。随着植物褪黑素研究的逐渐深入, 褪黑素在植物体内的合成途径及作用也更加明确。研究表明, 褪黑素在提高植物抵抗非生物和生物胁迫能力等方面具有调控作用。该文对近年来有关植物褪黑素参与非生物和生物胁迫的研究进展进行总结, 旨在为阐明褪黑素影响植物抵御逆境胁迫的调控机理提供参考。     

NAC转录因子在植物抗病和抗非生物胁迫反应中的作用

NAC转录因子是植物特有的一类转录因子,其共同特点是在N端含有一段高度保守、由约150个氨基酸组成的NAC结构域,而C端为高度变异的转录调控区。研究表明,NAC转录因子不仅参与植物生长发育的调控,而且在植物抗逆反应中具有重要的调控作用。文章着重介绍NAC转录因子在植物抗逆反应中的作用及其调控机制,并简要讨论NAC转录因子生物学功能的研究方向。     

Ectopic expression of an expansin-like B gene from wild Arachis enhances tolerance to both abiotic and biotic stresses

Plant expansins are structural cell wall-loosening proteins implicated in several developmental processes and responses to environmental constraints and pathogen infection. To date, there is limited information about the biological function of expansins-like B (EXLBs), one of the smallest and less-studied subfamilies of plant expansins. In the present study, we conducted a functional analysis of the wild Arachis AdEXLB8 gene in transgenic tobacco (Nicotiana tabacum) plants to clarify its putative role in mediating defense responses to abiotic and biotic stresses. First, its cell wall localization was confirmed in plants expressing an AdEXLB8:eGFP fusion protein, while nanomechanical assays indicated cell wall reorganization and reassembly due to AdEXLB8 overexpression without compromising the phenotype. We further demonstrated that AdEXLB8 increased tolerance not only to isolated abiotic (drought) and biotic (Sclerotinia sclerotiorum and Meloidogyne incognita) stresses but also to their combination. The jasmonate and abscisic acid signaling pathways were clearly favored in transgenic plants, showing an activated antioxidative defense system. In addition to modifications in the biomechanical properties of the cell wall, we propose that AdEXLB8 overexpression interferes with phytohormone dynamics leading to a defense primed state, which culminates in plant defense responses against isolated and combined abiotic and biotic stresses.     

抗逆相关AP2/EREBP转录因子研究进展

干旱、低温、土地盐碱化等非生物胁迫是影响植物生长发育以及作物产量的重要因素。近年来大量研究表明,多种转录因子参与调控植物对各种生物及非生物胁迫的应答与防御反应,与此同时人们对其作用机理的探索也日渐深入。AP2/ERF转录因子家族是植物所特有的一类转录因子,在拟南芥中该家族至少有146个成员;而在水稻中该基因家族多达181个,是已知水稻转录因子基因中最大的家族。这些编码含有一个保守APETALA(AP2)结构域的蛋白质可能在植物多个发育过程及应答外界环境信号过程中发挥重要功能。综述了AP2/EREBP类转录因子的结构特征及其功能特性,并重点讨论了它们在植物抗逆中的调控作用及其在植物抗逆性分子遗传改良上的意义。     

GABA signaling: a conserved and ubiquitous mechanism

In plants, research on γ-aminobutyric acid (GABA) has focused on its role as a metabolite, mainly in the context of responses to biotic and abiotic stresses. By contrast, studies of GABA in vertebrates have concentrated mainly on its role as a neurotransmitter and signaling molecule. Here, we discuss recent findings that point towards a possible role for GABA as a signaling molecule in plants.     

植物CBL-CIPK信号系统的功能及其作用机理

由类钙调磷酸酶B蛋白CBLs及其互作蛋白激酶CIPKs组成的信号系统是植物逆境胁迫信号传导的关键调控节点,是近几年植物逆境胁迫生理与分子生物学研究领域中的重要热点之一。文章主要介绍了CBLs和CIPKs基本功能结构域、CBL-CIPK信号系统在各种生物和非生物逆境胁迫响应、营养物质吸收及植物激素应答中的生物学功能及其作用机理。     

The rice pathogen-related protein 10 (JIOsPR10) is induced by abiotic and biotic stresses and exhibits ribonuclease activity

We previously reported that rice blast fungus or jasmonic acid induced the expression of rice pathogenesis-related class 10 (JIOsPR10) proteins (Kim et al. 2003, 2004). However, no further studies have been carried out to examine the expression, localization, and enzymatic activity of this protein in either developmental tissues or in tissues under abiotic stress conditions. In this study, rice JIOsPR10 was examined by Western blot analysis, immunolocalization, and biochemical assays. Western blots revealed that the JIOsPR10 protein was expressed in developmental tissues, including in flower and root. The protein was also expressed under abiotic stresses, such as occurs during senescence and wounding. Using immunohistochemical techniques, we determined that expression of JIOsPR10 was localized to the palea of flower, in the exodermis, and inner part of the endodermis of the root. In senescencing tissues of leaf and coleoptiles, its expression was localized in vascular bundles. The RNase activity using JIOsPR10 recombinant protein was determined and abolished after treatment with DTT in a native in-gel assay. To test this, we created JIOsPR10 mutant proteins containing serine substitutions of amino acids C81S, C83S, or both and examined their RNase activities. The activity of the C83S mutant was decreased in the agarose gel assay compared to the wild type. Taken together, we hypothesize that the JIOsPR10 protein possesses RNase activity that is sensitive to DTT, suggesting the importance of the disulfide bonding between cysteine residues and that it might play a role in constitutive self-defense mechanisms in plants against biotic and abiotic stresses.     

The pepper extracellular peroxidase CaPO2 is required for salt, drought and oxidative stress tolerance as well as resistance to fungal pathogens

In plants, biotic and abiotic stresses regulate the expression and activity of various peroxidase isoforms. Capsicum annuum EXTRACELLULAR PEROXIDASE 2 (CaPO2) was previously shown to play a role in local and systemic reactive oxygen species bursts and disease resistance during bacterial pathogen infection. Here, we report CaPO2 expression patterns and functions during conditions of biotic and abiotic stress. In pepper plants, CaPO2 expression was strongly induced by abscisic acid, but not by defense-related plant hormones such as salicylic acid, ethylene and jasmonic acid. CaPO2 was also strongly induced by abiotic and biotic stress treatments, including drought, cold, high salinity and infection by the hemibiotrophic fungal pathogen Colletotrichum coccodes. Loss-of-function of CaPO2 in virus-induced gene silenced pepper plants led to increased susceptibility to salt- and osmotic-induced stress. In contrast, CaPO2 overexpression in transgenic Arabidopsis thaliana plants conferred enhanced tolerance to high salt, drought, and oxidative stress, while also enhancing resistance to infection by the necrotrophic fungal pathogen Alternaria brassicicola. Taken together, these results provide evidence for the involvement of pepper extracellular peroxidase CaPO2 in plant defense responses to various abiotic stresses and plant fungal pathogens.     

Polyamines, polyamine oxidases and nitric oxide in development, abiotic and biotic stresses

Nitric oxide (NO), polyamines (PAs), diamine oxidases (DAO) and polyamine oxidases (PAO) play important roles in wide spectrum of physiological processes such as germination, root development, flowering and senescence and in defence responses against abiotic and biotic stress conditions. This functional overlapping suggests interaction of NO and PA in signalling cascades. Exogenous application of PAs putrescine, spermidine and spermine to Arabidopsis seedlings induced NO production as observed by fluorimetry and fluorescence microscopy using the NO-binding fluorophores DAF-2 and DAR-4M. The observed NO release induced by 1 mM spermine treatment in the Arabidopsis seedlings was very rapid without apparent lag phase. These observations pave a new insight into PA-mediated signalling and NO as a potential mediator of PA actions. When comparing the functions of NO and PA in plant development and abiotic and biotic stresses common to both signalling components it can be speculated that NO may be a link between PA-mediated stress responses filing a gap between many known physiological effects of PAs and amelioration of stresses. NO production indicated by PAs could be mediated either by H₂O₂, one reaction product of oxidation of PAs by DAO and PAO, or by unknown mechanisms involving PAs, DAO and PAO.     

丛枝菌根真菌在寄主植物抵御生物和非生物胁迫中的作用

丛枝菌根真菌(arbuscular mycorrhiza fungi,AMF)是生态系统中普遍存在的土壤微生物,能与绝大多数植物形成共生关系,它在寄主植物抵御生物和非生物胁迫中所起的作用逐渐引起国内外学者的关注.论文综述了丛枝菌根真菌在植物抵御非生物胁迫(重金属污染、有机污染、盐胁迫和干旱胁迫)以及生物胁迫(致病菌和线虫侵染)中的作用,并在此基础上提出了未来该领域值得进一步研究的方向.