植物耐盐的生理机制及基因工程新进展

在各种环境胁迫中,盐胁迫是造成作物减产的严重环境因素之一。主要从耐盐的生理机制和一些下游调节过程入手,包括:离子区隔化、渗透调节、激素调节、去毒化作用、光合途径的改变等,讨论了植物耐盐工程的新进展;同时还讨论了分子水平育种的影响因子。     

植物盐腺泌盐及发育研究进展

盐腺是泌盐盐生植物抵御盐胁迫的重要表皮结构，泌盐盐生植物可以通过盐腺将体内多余的盐离子排出体外，从而避免盐胁迫。盐腺作为泌盐盐生植物实现高效抗盐的重要结构，在逆境生理、发育和进化等领域都引起了关注和讨论，集中在盐腺的超微结构、生理功能、泌盐机制以及发育模式等不同层面已有广泛的研究报道。本文综述了盐腺结构、分泌机制、盐腺发育的研究进展，总结了盐腺泌盐的可能途径以及盐腺发育的调控方式和关键基因，对未来盐腺泌盐和发育的研究提出了相关见解，讨论了盐腺这一独特形态学结构对于植物耐盐性的作用，并对提高植物耐盐性、培育耐盐品种提出了理论依据和建议，有利于深入解析植物耐盐适应演化、培育抗盐作物和高效利用盐碱地。     

盐胁迫对植物叶绿素荧光影响的研究进展

盐胁迫是制约植物生长发育的主要非生物胁迫之一, 研究植物的耐盐机理对开发和有效利用盐碱地有重要的意义。叶绿素荧光动力技术作为研究植物光合生理状况及植物与逆境胁迫关系的理想方法, 可表明外界胁迫环境对植物光合器官的伤害程度。通过总结性阐述盐胁迫对植物叶绿素荧光的影响, 分别从盐分类型、植物类型、光照强度以及盐旱交互作用等方面分析了植物叶绿素荧光对盐胁迫的响应, 进而反映盐胁迫对植物光合能力的影响程度, 并提出增强植物抗盐性的途径, 包括施加外源物质、利用转基因技术、真菌的协同效应和培育耐盐品种。最后对叶绿素荧光动力技术在抗盐胁迫的运用前景进行了展望, 提出了当前研究需要解决的问题, 旨在为提高植物耐盐能力提供一定的理论依据。     

植物根系耐盐机制的研究进展

植物根系能够摄取土壤环境中的养分与水分,在植物的生长发育中起重要的作用。植物根系由于直接与土壤环境相接触会受到非生物胁迫较大的影响。盐胁迫是主要的非生物胁迫之一,对植物根系会产生较大的伤害。综述根系在组织形态和细胞水平上对盐胁迫的应答,以及根系响应盐胁迫的信号传导途径、转录因子与基因,对植物根部耐盐机制的解析和植物耐盐基因工程工具基因的挖掘具有重要意义。     

水稻耐盐/碱性鉴定评价方法

土壤盐/碱化是盐/碱稻作区水稻生产稳定发展的主要限制因素.为了提高水稻耐盐/碱性,扩大水稻种植面积,减轻盐/碱胁迫导致的水稻减产,许多学者广泛开展了水稻耐盐/碱性的基因型差异、生理生化、遗传及定位等研究,并取得了显著成绩.但国内在耐盐/碱性鉴定评价方法方面还缺乏统一标准,这影响着水稻耐盐/碱性研究的深入开展.本文阐述了国内外至今所采用的水稻耐盐/碱性鉴定方法、耐盐/碱指标和分级标准等,以期为我国水稻耐盐/碱性鉴定评价技术规范的制定以及水稻耐盐/碱性种质资源鉴定、生理生化分析和遗传育种提供参考依据.     

棉花的抗盐性及提高抗盐性的途径

棉花是较耐盐碱的作物,本文阐述了盐胁迫对棉花生长发育的影响,棉花的抗盐机理和提高棉花抗盐性的途径。     

藜科盐生植物的形态特征与耐盐分子机理研究进展

在非生物环境胁迫因子中,盐胁迫是造成农作物减产的主要因素之一.从藜科植物耐盐的形态生理学机制和分子生物学角度入手,讨论了藜科植物耐盐基因工程的新进展,探讨藜科盐生植物的盐胁迫机理,为利用基因工程手段培育耐盐植物奠定基础.     

植物耐盐蛋白的研究

植物耐盐蛋白的研究邵宏波,初立业（四平师范学院生物工程研究所,吉林四平１３６０００）关键词植物耐盐蛋白迄今为止,世界上还没有真正育成一种耐盐的作物品种。究其原因,就是不了解植物耐盐的分子生物学基础。近年来,有关植物在盐胁迫条件下基因表达变化的研究引起...     

植物同源多倍体耐盐性研究进展

多倍化是高等植物进化最重要的动力之一,多倍体植物由于基因组组成以及基因表达方面的变化,通常会表现出不同的生理现象,多倍体的抗性优于其同源二倍体祖先。土壤盐碱化和次生盐渍化是影响农作物生产的重要因素,严重制约着我国农业的可持续发展。同源多倍体植物耐盐能力较强,是作物遗传改良的重要种质资源,了解其耐盐机理对培育耐盐品种具有重要意义。本文从与盐胁迫相关的耐盐性进化、生理生化水平、细胞结构和分子层面等多角度总结了植物同源多倍体盐胁迫研究进展,并以作者所在研究团队培育出的多倍体西瓜为例讨论了多倍体抗逆性研究存在的问题及未来的发展方向,以期为多倍体抗逆优势机理研究提供参考。     

植物对盐胁迫响应的信号转导途径

植物通过调控复杂的信号网络来应对盐胁迫。近年来,随着植物基因工程技术的发展,对植物在盐胁迫下信号转导系统的研究取得了一定进展。本文以拟南芥为代表,对盐胁迫下参与调控植物耐盐生理响应的两大类主要信号转导途径——Ca2＋依赖型信号转导通路和丝裂原活化蛋白激酶（MAPK）级联反应途径的研究进展进行综述,主要介绍参与各信号转导通路的组件及诱发的耐盐生理响应等方面,并对该研究领域存在的问题及今后可能的研究方向进行展望。     

Insights into the Role of Gasotransmitters Mediating Salt Stress Responses in Plants

Salinity stress is one of the most significant global issues that negatively affect plant growth and development. Modern agricultural practices have expanded the destructive effects of salinity stress, affecting plants through immediate osmotic stress, followed by a slow onset of ionic or hyper-osmotic stress. Plants alteration and resistance to salinity stress involve complex physiological, biochemical, and molecular systems to maintain homeostasis. As of late, the investigation of gaseous molecules in plants has attained much consideration, particularly for abiotic stress. Abiotic stresses generally initiate gasotransmitter (GT) generation in plants. In the interim, these GTs enhance the accumulation and activities of few antioxidant molecules, check the destructiveness of reactive oxygen species (ROS), and improve plant resilience under different stress conditions. The current review presented the role of gaseous molecules in plants under salinity stress, which include nitric oxide (·NO), hydrogen sulfide (H₂S), hydrogen gas (H₂), carbon monoxide (CO), methane (CH₄), and the only gaseous phytohormone ethylene. Further, we highlighted the underlying molecular mechanisms of the gasotransmitter signaling and cross-talks in salinity stress. Also, we presented a general update on the inclusion of GT in salt stress response, including the research gaps and its applications in the advancement of salinity-resistant plants.

     

Distinct Cellular and Organismic Responses to Salt Stress

We have compared metabolic effects of high salinity betweenplants and cell suspension cultures from the facultative halophyteMesembryanthemum crystallinum (common ice plant). This plantshows developmentally-programmed inducibility for a switch fromC₃-photosynthesis to CAM (Crassulacean Acid Metabolism). Themetabolic switch is enhanced by environmental factors such asdrought, low temperature, and, most effectively, soil salinity.CAM induction is dependent on organized leaf tissue and cannotbe elicited by salt stress in suspension culture cells. In contrast,the accumulation of proline [Thomas et al. (1992) Plant Physiol.98: 626] is induced by NaCl in cultured cells as well as inplants and must be considered a cellular response to stress.We have extended our observations to include another trait ofsalt- and low-temperature-stress responses in the ice plant,the accumulation of putative osmoprotective sugars and sugaralcohols. In whole plants the cyclic sugar alcohol, pinitol,accumulates to amounts that approach 1 M during stress, whilein suspension cells no increase in sugar alcohols is observed.The distribution of carbon to different sugars is markedly differentbetween cells and plants under stress. Particularly obviousis the distinction between cell types in the different compositionof sugars and polyols, as exemplified by the epidermal bladdercells of ice plants. Ion contents and the content of sugarsand sugar alcohols of bladder cells indicate that Na⁺, Cl^–,pinitol and an unknown carbohydrate compound provide osmoticpressure in these cells, while organic anion concentrationsare low. With the ice plant, we conclude that cells in culturemimic only partly the stress response mechanisms of intact plantsand we hypothesize that communication between different tissuesis required to mount a complete environmental stress response. ⁴ Present address: Department of Botany Oklahoma State University,Stillwater, OK, 74078, U.S.A.     

Salt modulates gravity signaling pathway to regulate growth direction of primary roots in Arabidopsis

Plant root architecture is highly plastic during development and can adapt to many environmental stresses. The proper distribution of roots within the soil under various conditions such as salinity, water deficit, and nutrient deficiency greatly affects plant survival. Salinity profoundly affects the root system architecture of Arabidopsis (Arabidopsis thaliana). However, despite the inhibitory effects of salinity on root length and the number of roots, very little is known concerning influence of salinity on root growth direction and the underlying mechanisms. Here we show that salt modulates root growth direction by reducing the gravity response. Exposure to salt stress causes rapid degradation of amyloplasts in root columella cells of Arabidopsis. The altered root growth direction in response to salt was found to be correlated with PIN-FORMED2 (PIN2) messenger RNA abundance and expression and localization of the protein. Furthermore, responsiveness to gravity of salt overly sensitive (sos) mutants is substantially reduced, indicating that salt-induced altered gravitropism of root growth is mediated by ion disequilibrium. Mutation of SOS genes also leads to reduced amyloplast degradation in root tip columella cells and the defects in PIN2 gene expression in response to salt stress. These results indicate that the SOS pathway may mediate the decrease of PIN2 messenger RNA in salinity-induced modification of gravitropic response in Arabidopsis roots. Our findings provide new insights into the development of a root system necessary for plant adaptation to high salinity and implicate an important role of the SOS signaling pathway in this process.     

Salt Tolerant and Sensitive Rice Varieties Display Differential Methylome Flexibility under Salt Stress

DNA methylation has been referred as an important player in plant genomic responses to environmental stresses but correlations between the methylome plasticity and specific traits of interest are still far from being understood. In this study, we inspected global DNA methylation levels in salt tolerant and sensitive rice varieties upon salt stress imposition. Global DNA methylation was quantified using the 5-methylcytosine (5mC) antibody and an ELISA-based technique, which is an affordable and quite pioneer assay in plants, and in situ imaging of methylation sites in interphase nuclei of tissue sections. Variations of global DNA methylation levels in response to salt stress were tissue- and genotype-dependent. We show a connection between a higher ability of DNA methylation adjustment levels and salt stress tolerance. The salt-tolerant rice variety Pokkali was remarkable in its ability to quickly relax DNA methylation in response to salt stress. In spite of the same tendency for reduction of global methylation under salinity, in the salt-sensitive rice variety IR29 such reduction was not statistically supported. In ‘Pokkali’, the salt stress-induced demethylation may be linked to active demethylation due to increased expression of DNA demethylases under salt stress. In ‘IR29’, the induction of both DNA demethylases and methyltransferases may explain the lower plasticity of DNA methylation. We further show that mutations for epigenetic regulators affected specific phenotypic parameters related to salinity tolerance, such as the root length and biomass. This work emphasizes the role of differential methylome flexibility between salt tolerant and salt sensitive rice varieties as an important player in salt stress tolerance, reinforcing the need to better understand the connection between epigenetic networks and plant responses to environmental stresses.     

Salt stress-induced disassembly of Arabidopsis cortical microtubule arrays involves 26S proteasome-dependent degradation of SPIRAL1

The dynamic instability of cortical microtubules (MTs) (i.e., their ability to rapidly alternate between phases of growth and shrinkage) plays an essential role in plant growth and development. In addition, recent studies have revealed a pivotal role for dynamic instability in the response to salt stress conditions. The salt stress response includes a rapid depolymerization of MTs followed by the formation of a new MT network that is believed to be better suited for surviving high salinity. Although this initial depolymerization response is essential for the adaptation to salt stress, the underlying molecular mechanism has remained largely unknown. Here, we show that the MT-associated protein SPIRAL1 (SPR1) plays a key role in salt stress-induced MT disassembly. SPR1, a microtubule stabilizing protein, is degraded by the 26S proteasome, and its degradation rate is accelerated in response to high salinity. We show that accelerated SPR1 degradation is required for a fast MT disassembly response to salt stress and for salt stress tolerance.     

植物抗旱、耐盐基因概述

干旱和盐渍化是影响植物生长发育的重要逆境因子。逆境会诱导植物特定基因表达,以保护细胞免受逆境的危害。目前所报道的与植物抗旱、耐盐性相关的基因可分为四类：渗透保护物质生物合成的基因、编码与水分胁迫相关的功能蛋白基因、与信号传递和基因表达相关的调控基因、与细胞排毒抗氧化防御能力相关的酶基因。     

油菜素甾醇调控水稻盐胁迫应答的作用研究

油菜素甾醇(BR)作为植物内源激素, 广泛参与植物的生长发育过程及逆境应答。虽然BR调控生长发育的分子机制目前已相对清楚, 但在水稻(Oryza sativa)中, BR在逆境反应中的功能还鲜有报道。该研究系统分析了BR在高盐胁迫过程中的作用, 表明盐胁迫和逆境激素脱落酸可抑制BR合成基因D2和D11的表达, 典型的BR缺陷突变体(如d2-2和d61-1)则表现出对盐胁迫敏感性增强。此外, 通过对BR核心转录因子OsBZR1的过表达株系进行分析, 发现BR可显著诱导OsBZR1的去磷酸化, 盐胁迫对OsBZR1蛋白的积累水平和磷酸化状态均有调控作用。转录组数据分析表明, BR处理前后差异表达基因中有38.4%同时受到盐胁迫调控, 其中91.5%受到BR和高盐一致调控, 并显著富集在应激反应过程中。研究结果表明, BR正调控水稻的耐盐性, 而盐胁迫通过抑制BR合成来限制水稻的生长。     

ATPase与植物抗盐性

本文综述了高等植物细胞ATPase在盐胁迫下的活性变化及其调控机制。V型H+_ATPase与细胞离子区隔化和植物抗盐性密切相关。盐胁迫提高抗盐植物液泡膜H+_ATPase活性,主要是通过增加V型H+_ATPase主要功能亚基的基因表达以及蛋白质合成。盐胁迫通常降低质膜H+-ATPase活性,很可能是由于酶蛋白质合成受阻,质膜H+-ATPase活性的变化与盐胁迫的强度和时间长短有关。此外,本文还对ABA和Ca2+-CaM等胁迫信号物质对ATPase活性的调控及其与植物抗盐性的关系进行了总结。研究ATPase对盐胁迫的响应和调控机制,有助于阐明植物的盐生境适应机制,也有利于植物的抗盐育种工作。     

Proteomics Reveals New Salt Responsive Proteins Associated with Rice Plasma Membrane

The signaling processes in plants that initiate cellular responses to biotic and abiotic factors are believed to be located in the plasma membrane (PM). A better understanding of the PM proteome response to environmental stresses might lead to new strategies for improving stress-tolerant crops. A sub-cellular proteomics approach was applied to monitor changes in abundance of PM-associated protein in response to salinity, a key abiotic stress affecting rice productivity worldwide. Proteome was extracted from a root plasma-membrane-rich fraction of a rice salt tolerant variety, IR651, grown under saline and normal conditions. Comparative two-dimensional electrophoresis revealed that 24 proteins were differentially expressed in response to salt stress. From these, eight proteins were identified by mass spectrometry analysis. Most of the proteins identified are likely to be PM-associated and are known to be involved in several important mechanisms of plant adaptation to salt stress. These include regulation of PM pumps and channels, membrane structure, oxidative stress defense, signal transduction, protein folding, and the methyl cycle. To investigate the correlation between mRNA and protein level in response to salinity, we performed quantitative Real-Time PCR analysis of three genes that were salt responsive at the protein level, including 1,4-Benzoquinone reductase, a putative remorin and a hypersensitive induced response protein. No concordance was detected between the changes in levels of gene and protein expression. Our results indicate that the proteomics approach is suitable for expression analysis of membrane associated proteins under salt stress.