植物响应Cd胁迫研究进展

镉(Cd)是一种毒性极强的重金属污染物,位于土壤无机污染物首位。Cd因具有强流动性和溶解性而容易被植物体吸收,不仅影响植物正常生理代谢并降低作物品质,还能通过食物链的传递和富集危害人体健康,因此植物对Cd胁迫的响应机制已成为研究的热点。本文综述了Cd胁迫对植物生理代谢和分子层次危害的同时,总结了植物在Cd胁迫下进化出的耐受性机制,以期为培育低积累作物和超积累Cd污染土壤修复植物提供理论依据。     

双酚A与镉对植物光合作用的复合微生态效应

近年来,国内外学者研究了双酚A (BPA)及重金属镉(Cd)单一因子对植物光合作用的影响.但在自然背景下,污染多呈复合型,因此研究BPA和Cd对二者叠加的空间内植物光合作用的复合影响意义重大.本文综述了BPA对植物光合作用的影响及机制,及Cd对植物光合作用的影响及其机制,其中单一BPA和Cd对植物光合作用的影响均表现为:低浓度促进光合作用,高浓度反之.根据相关研究推测了植物在受到复合胁迫时的生态响应,相应的生理生化反应,及光合过程的响应机制.最后提出了BPA与Cd对植物复合胁迫可能开展的相关研究方向.     

植物重金属胁迫耐受机制

重金属是一类会对植物产生毒害作用的污染物,植物在长期进化过程中演变出耐受重金属胁迫的相关机制。以植物重金属耐受性为基础,对近几年来国内外植物响应重金属胁迫的耐受机制研究作一简要综述。主要概述了重金属对植物的胁迫影响及植物抗氧化系统,脯氨酸、可溶性糖、可溶性蛋白等渗透调节物质和不同类型基因家族等方面对植物耐受重金属胁迫机制的研究进展。以期为提高植物耐重金属胁迫能力及研究植物修复重金属污染土壤的应用奠定一定的基础。     

基于菌植互作的植物根际细菌钝化镉作用和机制研究进展

土壤重金属镉(Cd)污染严重危害农产品安全生产,植物根际细菌在钝化土壤Cd和帮助作物抵御Cd胁迫方面发挥重要作用。本文首先概括在修复Cd污染土壤中得到广泛应用的植物根际细菌种类,并从根际细菌直接吸附Cd、调整土壤理化特性、调控土壤微生物群落和其他作用4方面阐述了植物根际细菌对Cd的钝化作用,其次从菌植互作角度阐述植物根系分泌物与根际细菌群落相互影响对土壤Cd的钝化作用。最后展望重金属胁迫下植物根际钝化Cd核心菌群的构建,以在新兴学科与技术的快速发展中探明植物根系-微生物互作体系的分子机制,深入开展植物根际细菌钝化修复重金属污染土壤的理论研究和实践。     

植物响应联合胁迫机制的研究进展

自然界中, 植物通常面对多重联合胁迫。在全球气候变化日益加剧的背景下, 多重联合胁迫对植物生长发育及作物产量形成的不利影响日益显著。阐明植物响应和适应联合胁迫的生理与分子机制, 对人们理解植物对自然环境的适应机理, 及培育耐受联合胁迫的新品种有重要意义。研究表明, 植物响应联合胁迫的机制是特异的, 不能简单地从单一胁迫响应叠加来推断。植物遭受联合胁迫时, 各种生理、代谢和信号途径相互作用, 使得植物响应联合胁迫非常复杂。该文综述了植物响应联合胁迫的生理与分子机理的最新进展, 并阐述了植物响应联合胁迫的研究方法。     

红树植物淹水胁迫响应研究进展

潮汐淹水是红树植物面临的主要环境胁迫之一,也是导致目前红树林造林成活率低的一个关键因子。由于长期适应于水淹生境,红树植物发育出一套适应于潮间带生长的抗淹水机制。综述了与红树植物相关的抗淹水胁迫响应机制,包括了形态结构、生长、水分和光合作用、膜脂过氧化系统和根系脱氢酶系统、内源激素和胁迫多胺等5个方面。提出应用人工潮汐系统研究红树植物的淹水抗性机理是确定不同种类红树植物的耐淹水能力的有效手段。并指出生长的研究是淹水胁迫响应研究的基础,而与分子手段相结合的激素水平的研究将在红树植物抗性胁迫研究中得到重视。     

植物响应联合胁迫机制的研究进展

自然界中, 植物通常面对多重联合胁迫。在全球气候变化日益加剧的背景下, 多重联合胁迫对植物生长发育及作物产量形成的不利影响日益显著。阐明植物响应和适应联合胁迫的生理与分子机制, 对人们理解植物对自然环境的适应机理, 及培育耐受联合胁迫的新品种有重要意义。研究表明, 植物响应联合胁迫的机制是特异的, 不能简单地从单一胁迫响应叠加来推断。植物遭受联合胁迫时, 各种生理、代谢和信号途径相互作用, 使得植物响应联合胁迫非常复杂。该文综述了植物响应联合胁迫的生理与分子机理的最新进展, 并阐述了植物响应联合胁迫的研究方法。     

镉（Cd）胁迫下蓖麻蛋白质组学筛查及RcBSK7抗性功能研究

为揭示蓖麻(Ricinus communis)植株响应重金属镉(Cd)胁迫相关机制,筛选出蓖麻中参与Cd胁迫的抗性基因。本研究通过观察种子发芽及植株生长状态,最终确定以水处理的蓖麻植株为对照,研究其在3种剂量(300、700、1 000 mg·L^-1)Cd胁迫处理下的反应机制,以期为揭示蓖麻响应Cd胁迫的防御和解毒机制提供新思路。利用差异蛋白质组学分析蓖麻在Cd胁迫下的网络调控机制,即随着Cd胁迫浓度的增加,蓖麻植株分别通过阻隔根系对重金属Cd的吸收、提高自身抗氧化能力、抑制Cd²⁺运转以及诱导细胞程序性死亡等防御解毒过程以抵抗Cd胁迫损伤。根据组学分析结果筛选出差异显著基因RcBSK7,通过在拟南芥(Arabidopsis thaliana)中进行功能验证可知,该基因对提高蓖麻对Cd耐受性具有重要的作用。本研究增强了对蓖麻植株在3种Cd胁迫下多样性和复杂性的认识,为耐Cd基因鉴定和土壤中重金属污染修复提供了有价值的理论依据。     

植物涝渍胁迫应激机制研究进展

涝渍胁迫使植物从有氧呼吸转变为无氧呼吸,为了适应水淹环境,植物会根据自身特点启动应激机制。从植物形态、植物生理代谢、植物应激反应以及植物根际土壤微生物的变化阐述了植物对涝渍胁迫的应激机制,并对微生物生态响应机制与涝渍胁迫的关系方面的研究提出了展望,以期为植物抗性应激机制研究提供参考。     

铜、镉胁迫下外源NO介导的番茄解毒途径

一氧化氮(NO)作为信号分子,在抵御重金属胁迫中起重要作用,但对不同离子胁迫下的解毒机制尚缺乏研究.本研究采用营养液培养法,研究了铜(Cu)、镉(Cd)单一或复合胁迫下,番茄幼苗对Cu、Cd的吸收转运特性及对外源NO的响应机制.结果表明: 50 μmol·L^-1的Cu²⁺、Cd²⁺均显著抑制番茄植株的生长,其中Cd胁迫对生长的抑制效应远高于Cu胁迫.Cu、Cd单一或复合胁迫均使番茄根系Cu、Cd含量显著升高,但根系对Cu、Cd吸收存在严格选择性.根细胞对必需元素Cu表现出“奢侈吸收”的现象,而对毒性较强的Cd则吸收相对较少,胞内Cd浓度仅为Cu的1/10左右.外源NO处理可不同程度地缓解Cu、Cd胁迫,其中缓解Cd胁迫的效能更强.番茄对被动进入细胞的Cu、Cd具有相似的解毒机制:一方面,Cu、Cd胁迫诱导细胞质中产生谷胱甘肽(GSH)、植物螯合肽(PCs)和金属硫蛋白(MTs),络合过多的Cu、Cd离子,降低其生物毒性;另一方面,过多的Cu、Cd离子或螯合物被转运至液泡区隔化.外源NO通过调控GSH-GSSG(氧化型谷胱甘肽)氧化还原状态及GSH-PCs代谢方向的改变,促进Cu、Cd离子转运至液泡区隔化来缓解胁迫抑制;NO还可诱导植株叶片或根系表达更多的金属硫蛋白、GSH和PCs,而且上述响应普遍存在叠加效应.这可能是NO介导番茄对Cu、Cd胁迫的另一主要解毒途径.     

Physiological and biochemical analysis of mechanisms underlying cadmium tolerance and accumulation in turnip

The capacity of plants to accumulate cadmium (Cd) is significant for phytoremediation of Cd-polluted soils. Turnips cultivated in China include species featuring high Cd accumulation and some of these plants act as Cd hyperaccumulator landraces. These plants can accumulate over 100 mg Cd kg^-1 dry weight in leaves without injury. Hence, studies that explore mechanisms underlying Cd detoxification and transport in turnip plants are essential. In the present study, we compared physiological and biochemical changes in turnip leaves treated with two Cd concentrations to controls. We discovered that Cd stress significantly increased the enzymatic activities or compound contents in the antioxidant system, including members of the glutathione-ascorbic acid cycle, whereas oxidation of reactive oxygen species (ROS) remained stable. Cd treatments also increased the contents of phytochelatins as well as a number of amino acids. Based on these results, we conclude that turnips initiate a series of response processes to manage Cd treatment. First, the antioxidant system maintaining ROS homeostasis and osmotic adjustment is excited to maintain stability of cell osmotic potential. Cd is chelated into its stable form to reduce its toxicity. Cd is possibly transported to vacuoles or non-protoplasts for isolation. Amino acid synthesis may directly and indirectly play an important role in these processes. This study partly revealed physiological and biochemical mechanisms underlying turnip response to Cd stress and provides information on artificially increasing or decreasing Cd accumulation in turnips and other plants.     

Effects of nitrogen on the activity of antioxidant enzymes and gene expression in leaves of Populus plants subjected to cadmium stress

The research aimed to verify the important physiological effect of nitrogen (N) on plants exposed to cadmium (Cd). The poplar plants were grown in a Hoagland nutrient solution and treated with extra N, Cd, and N + Cd. After treatment, plant growth and chlorophyll content were recorded. The oxidative stress, the activity of antioxidant enzymes, and the expression of related genes were also examined. The results indicated the plants treated with sole Cd presented obvious toxicity symptoms, i.e. growth inhibition, reactive oxygen species accumulation, and chlorophyll content decrement. However, when N was added to the plants under Cd stress, plant growth was enhanced, chlorophyll synthesis was promoted, and the oxidative stress was alleviated. Further, the expression of antioxidant enzymes genes was upregulated by N. The results indicated that N partially reversed the toxic effect of Cd on poplar plants, which can provide new methodology to enhance the phytoremediation technology for heavy metal pollution soil.     

镉毒害下植物氧化胁迫发生及其信号调控机制的研究进展

土壤重金属污染引发了一系列严峻的环境问题.其中,镉(Cd)是生物毒性最强的重金属元素之一.活性氧(ROS)过量积累引起的氧化胁迫,是Cd毒害植物的主要原因之一.本文围绕Cd胁迫引起的ROS积累及清除过程,重点阐述介导上述过程的一些信号调控物质包括一氧化氮(NO)、钙(Ca)、植物激素如生长素(IAA)和脱落酸(ABA)等及有丝分裂原活化蛋白激酶(MAPKs)的变化及其在缓解Cd诱导的氧化胁迫中的作用,以期为今后植物抗Cd胁迫生理生化机制的研究提供一定的理论依据.     

Role of salicylic acid in resistance to cadmium stress in plants

Key message

We review and introduce the importance of salicylic acid in plants under cadmium stress, and provide insights into potential regulatory mechanisms for alleviating cadmium toxicity.

Abstract

Cadmium (Cd) is a widespread and potentially toxic environmental pollutant, originating mainly from rapid industrial processes, the application of fertilizers, manures and sewage sludge, and urban activities. It is easily taken up by plants, resulting in obvious toxicity symptoms, including growth retardation, leaf chlorosis, leaf and root necrosis, altered structures and ultrastructures, inhibition of photosynthesis, and cell death. Therefore, alleviating Cd toxicity in plants is a major aim of plant research. Salicylic acid (SA) is a ubiquitous plant phenolic compound that has been used in many plant species to alleviate Cd toxicity by regulating plant growth, reducing Cd uptake and distribution in plants, protecting membrane integrity and stability, scavenging reactive oxygen species and enhancing antioxidant defense system, improving photosynthetic capacity. Furthermore, SA functions as a signaling molecule involved in the expression of several important genes. Significant amounts of research have focused on understanding SA functions and signaling in plants under Cd stress, but several questions still remain unanswered. In this article, the influence of SA on Cd-induced stress in plants and the potential regulation mechanism for alleviating Cd toxicity are reviewed.

     

Morphogenic effects of abiotic stress: reorientation of growth in Arabidopsis thaliana seedlings

Abiotic stress responses include changes in physiological and biochemical processes as well as morphological and developmental patterns. It has remained an enigma which mechanisms are responsible for stress-induced morphogenesis. In this paper we demonstrate that stress induced phenotypes comprise a re-orientation rather than a cessation of growth. Moreover, strong similarities between the phenotypes induced by excess copper, paraquat, salicylic acid and a hydrogen peroxide analogue, indicate that a common molecular-physiological response system mediates these morphogenic stress responses. It is proposed that reactive oxygen species play a key role in controlling the architectural changes in stressed Arabidopsis thaliana seedlings.We found that phenotypes of plants exposed to stress resemble, in terms of the redistribution of growth, plants altered in phytohormone metabolism. We also found that plants in which polar auxin transport is blocked with TIBA, strongly resemble, but are not identical to, plants exposed to abiotic stress. Based on the stress induced formation of lateral roots, we surmise that stress induces local auxin accumulation near the root pericycle.     

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.

     

Effects of Melatonin on Growth,Physiology and Gene Expression in Rice Seedlings Under Cadmium Stress

Melatonin (MLT) is a hormonal substance found in many organisms and can improve plant stress resistance. In this study, the japonica rice variety Y32 and indica rice variety NJ6 were cultivated in hydroponics under different concentrations of CdCl₂ at the two-leaf stage. The growth, physiological and biochemical responses of the seedlings and the expression of cadmium (Cd)-related genes under exogenous melatonin (MLT) treatment were assessed. The results indicated that Cd stress destroyed the dynamic balance between reactive oxygen species (ROS) production and removal, resulting in ROS accumulation, membrane lipid peroxidation, and impaired growth and development. Following the application of exogenous MLT to rice seedlings, increases in plant biomass including both underground and above-ground areas were observed. MLT also scavenged the inhibition of superoxide dismutase (SOD) and peroxidase (POD) in a concentration dependent manner in response to Cd stress. Catalase (CAT) activity and malondialdehyde (MDA) expression also decreased following MLT treatment. Amongst the six Cd-related genes assessed, five genes were down-regulated and one was up-regulated in response to MLT treatment. Taken together, these data demonstrate that MLT improves the resilience of rice seedlings at the biochemical, physiological, and molecular levels, and diminishes the damage caused by Cd stress.     

Photosynthesis and antioxidative defense mechanisms in deciphering drought stress tolerance of crop plants

Crop plants are regularly exposed to an array of abiotic and biotic stresses, among them drought stress is a major environmental factor that shows adverse effects on plant growth and productivity. Because of this these factors are considered as hazardous for crop production. Drought stress elicits a plethora of responses in plants resulting in strict amendments in physiological, biochemical, and molecular processes. Photosynthesis is the most fundamental physiological process affected by drought due to a reduction in the CO₂ assimilation rate and disruption of primary photosynthetic reactions and pigments. Drought also expedites the generation of reactive oxygen species (ROS), triggering a cascade of antioxidative defense mechanisms, and affects many other metabolic processes as well as affecting gene expression. Details of the drought stress-induced changes, particularly in crop plants, are discussed in this review, with the major points: 1) leaf water potentials and water use efficiency in plants under drought stress; 2) increased production of ROS under drought leading to oxidative stress in plants and the role of ROS as signaling molecules; 3) molecular responses that lead to the enhanced expression of stress-inducible genes; 4) the decrease in photosynthesis leading to the decreased amount of assimilates, growth, and yield; 5) the antioxidant defense mechanisms comprising of enzymatic and non-enzymatic antioxidants and the other protective mechanisms; 6) progress made in identifying the drought stress tolerance mechanisms; 7) the production of transgenic crop plants with enhanced tolerance to drought stress.     

Regulation of plant reactive oxygen species (ROS) in stress responses: learning from AtRBOHD

Reactive oxygen species (ROS) are constantly produced in plants, as the metabolic by-products or as the signaling components in stress responses. High levels of ROS are harmful to plants. In contrast, ROS play important roles in plant physiology, including abiotic and biotic tolerance, development, and cellular signaling. Therefore, ROS production needs to be tightly regulated to balance their function. Respiratory burst oxidase homologue (RBOH) proteins, also known as plant nicotinamide adenine dinucleotide phosphate oxidases, are well studied enzymatic ROS-generating systems in plants. The regulatory mechanisms of RBOH-dependent ROS production in stress responses have been intensively studied. This has greatly advanced our knowledge of the mechanisms that regulate plant ROS production. This review attempts to integrate the regulatory mechanisms of RBOHD-dependent ROS production by discussing the recent advance. AtRBOHD-dependent ROS production could provide a valuable reference for studying ROS production in plant stress responses.