沙冬青逆境胁迫分子生物学研究进展

逆境胁迫是影响植物生长发育的重要因素,植物的抗逆机理是分子生物学研究的重要领域。随着分子生物学技术的发展,有关植物抗逆方面的研究已取得了很大的进展,初步揭示了植物应对逆境胁迫适应性的分子机理。沙冬青是我国温带荒漠地区惟一的常绿灌木,具有很强的抗逆性,是开展植物逆境胁迫研究和抗逆基因筛选的理想材料。本文综合论述了抗逆植物沙冬青的抗逆机理及逆境胁迫相关基因的分子生物学研究进展,为植物抗逆基因工程发掘更多的基因资源和抗旱植物的抗逆性研究提供思路。     

Potassium transport and plant salt tolerance

Salinity is a major abiotic stress affecting approximately 7% of the world's total land area resulting in billion dollar losses in crop production around the globe. Recent progress in molecular genetics and plant electrophysiology suggests that the ability of a plant to maintain a high cytosolic K⁺/Na⁺ ratio appears to be critical to plant salt tolerance. So far, the major efforts of plant breeders have been aimed at improving this ratio by minimizing Na⁺ uptake and transport to shoot. In this paper, we discuss an alternative approach, reviewing the molecular and ionic mechanisms contributing to potassium homeostasis in salinized plant tissues and discussing prospects for breeding for salt tolerance by targeting this trait. Major K⁺ transporters and their functional expression under saline conditions are reviewed and the multiple modes of their control are evaluated, including ameliorative effects of compatible solutes, polyamines and supplemental calcium. Subsequently, the genetic aspects of inheritance of K⁺ transport 'markers' are discussed in the general context of salt tolerance as a polygenic trait. The molecular identity of 'salt tolerance' genes is analysed, and prospects for future research and breeding are examined.     

Sequence similarity based identification of abiotic stress responsive genes in chickpea

Chickpea (Cicer arietinum L.) is an important food legume crop, particularly for the arid regions including Indian subcontinent. Considering the detrimental effect of drought, temperature and salt stress on crop yield, efforts have been initiated in the direction of developing improved varieties and designing alternate strategies to sustain chickpea production in adverse environmental conditions. Identification of genes that confer abiotic stress tolerance in plants remains a challenge in contemporary plant breeding. The present study focused on the identification of abiotic stress responsive genes in chickpea based on sequence similarity approach exploiting known abiotic stress responsive genes from model crops or other plant species. Ten abiotic stress responsive genes identified in other plants were partially amplified from eight chickpea genotypes and their presence in chickpea was confirmed after sequencing the PCR products. These genes have been functionally validated and reported to play significant role in stress response in model plants like Arabidopsis, rice and other legume crops. Chickpea EST sequences available at NCBI EST database were used for the identification of abiotic stress responsive genes. A total of 8,536 unique coding long sequences were used for identification of chickpea homologues of these abiotic stress responsive genes by sequence similarity search (BLASTN and BLASTX). These genes can be further explored towards achieving the goal of developing superior chickpea varieties providing improved yields under stress conditions using modern molecular breeding approaches.     

Combinatorial Interactions of Biotic and Abiotic Stresses in Plants and Their Molecular Mechanisms: Systems Biology Approach

Plants are continually facing biotic and abiotic stresses, and hence, they need to respond and adapt to survive. Plant response during multiple and combined biotic and abiotic stresses is highly complex and varied than the individual stress. These stresses resulted alteration of plant behavior through regulating the levels of microRNA, heat shock proteins, epigenetic variations. These variations can cause many adverse effects on the growth and development of the plant. Further, in natural conditions, several abiotic stresses causing factors make the plant more susceptible to pathogens infections and vice-versa. A very intricate and multifaceted interactions of various biomolecules are involved in metabolic pathways that can direct towards a cross-tolerance and improvement of plant’s defence system. Systems biology approach plays a significant role in the investigation of these molecular interactions. The valuable information obtained by systems biology will help to develop stress-resistant plant varieties against multiple stresses. Thus, this review aims to decipher various multilevel interactions at the molecular level under combinatorial biotic and abiotic stresses and the role of systems biology to understand these molecular interactions.     

Emerging tools,concepts and ideas to track the modulator genes underlying plant drought adaptive traits: An overview

Crop vulnerability to multiple abiotic stresses is increasing at an alarming rate in the current global climate change scenario, especially drought. Crop improvement for adaptive adjustments to accomplish stress tolerance requires a comprehensive understanding of the key contributory processes. This requires the identification and careful analysis of the critical morpho-physiological plant attributes and their genetic control. In this review we try to discuss the crucial traits underlying drought tolerance and the various modes followed to understand their molecular level regulation. Plant stress biology is progressing into new dimensions and a conscious attempt has been made to traverse through the various approaches and checkpoints that would be relevant to tackle drought stress limitations for sustainable crop production.     

Molecular genetics and functional genomics of abiotic stress-responsive genes in oilseed rape (<Emphasis Type="Italic">Brassica napus</Emphasis> L.): a review of recent advances and future

Abiotic stresses are the key factors which negatively influence plant development and productivity and are the main cause of extensive agricultural production losses worldwide. Brassica napus is an oilseed crop of global economic significance and major contributor to the total oilseed production, quite often encounters abiotic stresses, resulting in reduced agricultural productivity. Hence, there is an immediate need being felt to raise B. napus cultivars which would be more suitable for various abiotic stress conditions presently and in the years to come. Biotechnology and molecular plant breeding has emerged as an important tool for molecular understanding of plant response to various abiotic stresses. Currently, various stress-responsive genes and mechanisms have been identified and functionally characterized in model plant Arabidopsis and other major crop plants such as Oryza sativa and Zea mays. However, very inadequate success has been achieved in this direction in a major oilseed crop such as B. napus. In this review, we present the latest methods and approaches of studying abiotic stress in B. napus. In this review, we describe the genes functioning as markers for crop breeding and discuss the recent progress and advances in genome editing by break through CRISPR/Cas9 multigene–multiplex approaches for developing multiple abiotic stress tolerance with our on-going research as a scheme. We also throw some light on molecular genetics, plant breeding and abiotic stress biotechnology of B. napus which offer a new prospective on the research directions for the practical plant breeding and functional genomics of B. napus in response to different abiotic stress conditions.     

白桦BpERF98基因的遗传转化及非生物胁迫应答反应

非生物胁迫严重影响植物的生长发育,植物通过内部的分子调控机制抵御这种伤害,其中转录因子发挥了至关重要的作用。从野生型白桦（Betula platyphylla）叶片克隆BpERF98基因,通过农杆菌介导法获得过表达BpERF98的转基因白桦植株。测量转基因白桦和野生型白桦在低温、冻害和盐胁迫下的生理指标并进行差异性分析。通过分析发现,在非生物胁迫下转基因白桦的丙二醛含量及相对电导率均低于野生型株系,且转基因株系SOD和POD活性的增长明显高于野生型株系。结果表明,过表达BpERF98基因可以提高白桦对非生物胁迫的抵御能力,这为研究白桦在非生物胁迫下形成的分子机制及白桦抗性分子育种提供了依据。     

Microbial rescue to plant under habitat-imposed abiotic and biotic stresses

Habitat-imposed abiotic and biotic stress is a serious condition and is also a land-degradation problem in arid and semi-arid regions, causing major problem for crop productivity. Most of the cultivable and a least half of irrigated lands around the world are severely affected by environmental stresses. However, in these conditions, there are plant populations successfully adapted and evolutionarily different in their strategy of stress tolerance. Vascular plants do not function as autonomous individuals, but house diverse communities of symbiotic microbes. The role of these microbes can no longer be ignored. Microbial interactions are critical not only for host but also for fungal survival in stressed environments. Plants benefit extensively by harboring these associated microbes; they promote plant growth and confer enhanced resistance to various pathogens by producing antibiotics. To date, improvements in plant quality, production, abiotic and biotic stress resistance, nutrient, and water use have relied largely on manipulating plant genomes by breeding and genetic modification. Increasing evidence indicates that the function of symbiotic microbes seems to parallel more than one of these characteristics.     

Halophytes as a source of genes for abiotic stress tolerance

Agricultural productivity is majorly impacted due to various abiotic stresses, particularly salinity and drought. Halophytes serve as an excellent resource for identifying and developing new crop systems, as these grow very luxuriously in very high saline soils. Understanding salinity stress tolerance mechanisms in such plants is an important step towards generating crop varieties that can cope with environmental stresses. Use of modern tools of ‘omics’ analyses and small RNA sequencing has helped to gain insights into the complex plant stress responses. Salinity tolerance being a multigenic trait requires a combination of strategies and techniques to successfully develop improved crops varieties. Many transgenic crops are being developed through genetic transformation. Besides marker-assisted breeding/QTL approaches are also being used to improve abiotic stress tolerance. In this review, we focus on the recent developments in the utilization of halophytes as a source of genes for genetic improvement in abiotic stress tolerance of crops.     

AOX--a functional marker for efficient cell reprogramming under stress?

Functional markers for stress tolerance can be used in plant breeding to identify genotypes with high yield stabilities under various conditions. Thus, a good marker should show a strong correlation with favourable adaptive plant behaviour. The efficient reprogramming of target cells for yield determination is currently considered to be the most important step towards defining abiotic stress tolerance. In this Opinion article, we propose a role for the alternative oxidase (AOX) gene as a marker for genetic variation in cell reprogramming and yield stability. Evidence to support this idea comes from the metabolic role of alternative respiration under stress, the link between AOX activity and differential growth, and the single nucleotide polymorphism recently observed in AOX genes. We propose an innovative, interdisciplinary and global research strategy for future experimentation on AOX genes that could have an application in plant breeding.     

Research Advances in Mechanisms of Turfgrass Tolerance to Abiotic Stresses: From Physiology to Molecular Biology

Turgrfass used on landscapes, parks, sports fields, and golf courses has significant ecological, environmental, and economic impacts. The economic value of seed production of turfgrasses is second to hybrid corn. The land area cultivated with turfgrass is increasing due to rapid urban development. Turfgrass is often subjected to various abiotic stresses, which cause declines in aesthetic quality, functionality and seed yield. Among abiotic stresses, drought, salinity, heat, and low temperature are the most common detrimental factors for turfgrass growth in various regions. Thorough understanding of mechanisms of turfgrass stress responses is vital for the development of superior stress-tolerant germplasm through breeding and biotechnology. Significant progress has been made in turfgrass stress physiology and molecular biology in recent decades, but research for turfgrasses generally lags behind that of the major Poaceae crops, particularly at the molecular and genomic levels. This review focuses on research advances in turfgrass stress physiology and provides an overview of limited information on gene discovery, genetic transformation, and molecular marker development for improving stress tolerance, with emphasis on drought, salinity, heat, and low temperature stress. Major growth and physiological traits associated with these stresses, as well as metabolic and molecular factors regulating various traits for turfgrass tolerance to each stress are discussed. Future research at the systems biology level and through genomic sequencing is paramount for further insights on fundamental mechanisms of turfgrass stress tolerance and for improving turfgrass tolerance to various environmental stresses.     

Oxylipins and plant abiotic stress resistance

Oxylipins are signaling molecules formed enzymatically or spontaneously from unsaturated fatty acids in all aerobic organisms. Oxylipins regulate growth, development, and responses to environmental stimuli of organisms. The oxylipin biosynthesis pathway in plants includes a few parallel branches named after first enzyme of the corresponding branch as allene oxide synthase, hydroperoxide lyase, divinyl ether synthase, peroxygenase, epoxy alcohol synthase, and others in which various biologically active metabolites are produced. Oxylipins can be formed non-enzymatically as a result of oxygenation of fatty acids by free radicals and reactive oxygen species. Spontaneously formed oxylipins are called phytoprostanes. The role of oxylipins in biotic stress responses has been described in many published works. The role of oxylipins in plant adaptation to abiotic stress conditions is less studied; there is also obvious lack of available data compilation and analysis in this area of research. In this work we analyze data on oxylipins functions in plant adaptation to abiotic stress conditions, such as wounding, suboptimal light and temperature, dehydration and osmotic stress, and effects of ozone and heavy metals. Modern research articles elucidating the molecular mechanisms of oxylipins action by the methods of biochemistry, molecular biology, and genetics are reviewed here. Data on the role of oxylipins in stress signal transduction, stress-inducible gene expression regulation, and interaction of these metabolites with other signal transduction pathways in cells are described. In this review the general oxylipin-mediated mechanisms that help plants to adjust to a broad spectrum of stress factors are considered, followed by analysis of more specific responses regulated by oxylipins only under certain stress conditions. New approaches to improvement of plant resistance to abiotic stresses based on the induction of oxylipin-mediated processes are discussed.