Plant miRNAs and abiotic stress responses

MicroRNAs (miRNAs) are endogenous approximate 22 nucleotide (nt) small non-coding regulatory RNAs that play important roles in plants by targeting mRNAs for cleavage or translational repression. Plant miRNAs were described 10 years later than animal miRNAs did; there are some differences between them in terms of biogenesis and mechanism of function. Furthermore, plant miRNAs have been shown to be involved in various stress responses, such as oxidative, mineral nutrient deficiency, dehydration, and even mechanical stimulus. In this review, we focus on the current understanding of biogenesis and regulatory mechanisms of plant miRNAs. We also highlight specific examples of miRNAs, which are important regulators for plant abiotic stress responses.     

Genome‐wide identification,expression analysis of auxin‐responsive GH3 family genes in maize (Zea mays L.) under abiotic stresses

Auxin is involved in different aspects of plant growth and development by regulating the expression of auxinresponsive family genes. As one of the three major auxinresponsive families, GH3(Gretchen Hagen3) genes participate in auxin homeostasis by catalyzing auxin conjugation and bounding free indole-3-acetic acid(IAA) to amino acids.However, how GH3 genes function in responses to abiotic stresses and various hormones in maize is largely unknown.Here, the latest updated maize(Zea mays L.) reference genome sequence was used to characterize and analyze the Zm GH3 family genes from maize. The results showed that 13 Zm GH3 genes were mapped on fi ve maize chromosomes(total10 chromosomes). Highly diversi fi ed gene structures and tissue-speci fi c expression patterns suggested the possibility of function diversi fi cation for these genes in response to environmental stresses and hormone stimuli. The expression patterns of Zm GH3 genes are responsive to several abiotic stresses(salt, drought and cadmium) and major stress-relatedhormones(abscisic acid, salicylic acid and jasmonic acid)Various environmental factors suppress auxin free IAA contents in maize roots suggesting that these abiotic stresses and hormones might alter GH3-mediated auxin levels. The respon siveness of Zm GH3 genes to a wide range of abiotic stresses and stress-related hormones suggested that Zm GH3 s are involved in maize tolerance to environmental stresses.     

The molecular mechanism of plasma membrane H+-ATPases in plant responses to abiotic stress

Plasma membrane H⁺-ATPases (PM H⁺-ATPases) are critical proton pumps that export protons from the cytoplasm to the apoplast. The resulting proton gradient and difference in electrical potential energize various secondary active transport events. PM H⁺-ATPases play essential roles in plant growth, development, and stress responses. In this review, we focus on recent studies of the mechanism of PM H⁺-ATPases in response to abiotic stresses in plants, such as salt and high pH, temperature, drought, light, macronutrient deficiency, acidic soil and aluminum stress, as well as heavy metal toxicity. Moreover, we discuss remaining outstanding questions about how PM H⁺-ATPases contribute to abiotic stress responses.     

Involvement of polyamines in plant response to abiotic stress

Environmental stresses are the major cause of crop loss worldwide. Polyamines are involved in plant stress responses. However, the precise role(s) of polyamine metabolism in these processes remain ill-defined. Transgenic approaches demonstrate that polyamines play essential roles in stress tolerance and open up the possibility to exploit this strategy to improve plant tolerance to multiple environmental stresses. The use of Arabidopsis as a model plant enables us to carry out global expression studies of the polyamine metabolic genes under different stress conditions, as well as genome-wide expression analyses of insertional-mutants and plants over-expressing these genes. These studies are essential to dissect the polyamine mechanism of action in order to design new strategies to increase plant survival in adverse environments.     

Hydrogen sulfide regulates abiotic stress tolerance and biotic stress resistance in Arabidopsis

Hydrogen sulfide (H2S) is an important gaseous molecule in various plant developmental processes and plant stress responses. In this study, the transgenic Arabidopsis thaliana plants with modulated exp...     

谷子光敏色素基因光周期、非生物胁迫响应特性及关键自然变异位点鉴定北大核心CSCD

比较分析光敏色素基因家族成员对光周期、非生物胁迫响应模式并鉴定其有利自然变异类型,为全面了解光敏色素基因家族在光周期调控谷子生长发育及应对非生物胁迫中的作用机制、开展关键性状的分子辅助选择奠定基础。文中利用RT-PCR技术从超晚熟谷子农家种‘毛粟’中克隆了3个光敏色素基因SiPHYA、SiPHYB和SiPHYC;在进行生物信息学分析后,利用荧光定量PCR技术研究了3个基因的光周期调控模式及对聚乙二醇(polyethylene glycol,PEG)模拟干旱、自然干旱、脱落酸(abscisic acid,ABA)、高温、Na Cl五种非生物胁迫的响应特性;最后检测这3个基因在160份谷子材料的突变位点,通过单倍型分析确定基因的功能效应。结果表明,获得了基因SiPHYA、SiPHYB和SiPHYC包含完整编码区的c DNA序列,长度分别为3 981、3 953、3 764 bp,其中基因SiPHYB和SiPHYC具有较近的进化关系。基因SiPHYA、SiPHYB和SiPHYC均受光周期调控,但光周期对SiPHYB、SiPHYC昼夜表达模式的影响要强于SiPHYA;短日照条件临近抽穗SiPHYA、SiPHYB表达水平显著低于长日照,暗示其在谷子长日照抑制抽穗中发挥作用。SiPHYB和SiPHYC共同响应PEG模拟干旱、自然干旱、ABA、高温4种胁迫;SiPHYA和SiPHYB以不同方式响应盐胁迫,SiPHYC没有参与谷子盐胁迫响应过程。基于160份谷子材料重测序数据发现基因SiPHYB高度保守,基因SiPHYA含有两个错义突变:单核苷酸多态性(single nucleotide polymorphism,SNP) 7 034 522;,SNP7 036 657;,导致延迟抽穗、增加株高。基因SiPHYC含有一个错义突变(SNP5 414 823;),导致短日照缩短抽穗期,长日照延长抽穗期,对株高、穗长的增加作用不受光温环境影响。光周期对基因SiPHYA、SiPHYB和SiPHYC具有不同的调控作用,除了盐胁迫,SiPHYB和SiPHYC共同响应多种非生物胁迫,相比参考基因型,SiPHYA、SiPHYC突变延迟抽穗、增加株高和穗长。     

Progress and challenges for abiotic stress proteomics of crop plants

Plants are continually challenged to recognize and respond to adverse changes in their environment to avoid detrimental effects on growth and development. Understanding the mechanisms that crop plants employ to resist and tolerate abiotic stress is of considerable interest for designing agriculture breeding strategies to ensure sustainable productivity. The application of proteomics technologies to advance our knowledge in crop plant abiotic stress tolerance has increased dramatically in the past few years as evidenced by the large amount of publications in this area. This is attributed to advances in various technology platforms associated with MS‐based techniques as well as the accessibility of proteomics units to a wider plant research community. This review summarizes the work which has been reported for major crop plants and evaluates the findings in context of the approaches that are widely employed with the aim to encourage broadening the strategies used to increase coverage of the proteome     

非生物胁迫下耐辐射异常球菌drB0118基因功能分析

【目的】鉴定和确定被预测为编码干燥相关蛋白的耐辐射异常球菌(Deinococcus radiodurans) drB0118基因功能,探讨该基因对盐、渗透和氧化胁迫抗性的作用。【方法】构建drB0118基因缺失突变株(ΔB0118),通过氯化钠、D-山梨糖醇和过氧化氢等胁迫冲击实验及氧化胁迫条件下qRT-PCR分析,研究drB0118突变对非生物胁迫反应及氧化胁迫相关基因表达的影响。【结果】drB0118突变导致菌株对NaCl和D-sorbitol胁迫的抗性降低;对氧化胁迫(H2O2)敏感;qRT-PCR分析显示,drB0118突变引起氧化胁迫抗性基因pod和oxyR分别下调4倍和10倍。【结论】D. radiodurans中drB0118参与了盐、渗透和氧化等多种非生物胁迫反应。     

Identification and annotation of abiotic stress responsive candidate genes in peanut ESTs

Peanut (Arachis hypogaea L.) ranks fifth among the world oil crops and is widely grown in India and neighbouring countries. Due to its large and unknown genome size, studies on genomics and genetic modification of peanut are still scanty as compared to other model crops like Arabidopsis, rice, cotton and soybean. Because of its favourable cultivation in semi-arid regions, study on abiotic stress responsive genes and its regulation in peanut is very much important. Therefore, we aim to identify and annotate the abiotic stress responsive candidate genes in peanut ESTs. Expression data of drought stress responsive corresponding genes and EST sequences were screened from dot blot experiments shown as heat maps and supplementary tables, respectively as reported by Govind et al. (2009). Some of the screened genes having no information about their ESTs in above mentioned supplementary tables were retrieved from NCBI. A phylogenetic analysis was performed to find a group of utmost similar ESTs for each selected gene. Individual EST of the said group were further searched in peanut ESTs (1,78,490 whole EST sequences) using stand alone BLAST. For the prediction as well as annotation of abiotic stress responsive selected genes, various tools (like Vec-Screen, Repeat Masker, EST-Trimmer, DNA Baser, WISE2 and I-TASSER) were used. Here we report the predicted result of Contigs, domain as well as 3D structure for HSP 17.3KDa protein, DnaJ protein and Type 2 Metallothionein protein.     

Physiological aspects of raffinose family oligosaccharides in plants: protection against abiotic stress

Abiotic stresses resulting from water deficit, high salinity or periods of drought adversely affect plant growth and development and represent major selective forces during plant evolution. The raffinose family oligosaccharides (RFOs) are synthesised from sucrose by the subsequent addition of activated galactinol moieties donated by galactinol. RFOs are characterised as compatible solutes involved in stress tolerance defence mechanisms, although evidence also suggests that they act as antioxidants, are part of carbon partitioning strategies and may serve as signals in response to stress. The key enzyme and regulatory point in RFO biosynthesis is galactinol synthase (GolS), and an increase of GolS in expression and activity is often associated with abiotic stress. It has also been shown that different GolS isoforms are expressed in response to different types of abiotic stress, suggesting that the timing and accumulation of RFOs are controlled for each abiotic stress. However, the accumulation of RFOs in response to stress is not universal and other functional roles have been suggested for RFOs, such as being part of a carbon storage mechanism. Transgenic Arabidopsis plants with increased galactinol and raffinose concentrations had better ROS scavenging capacity, while many sugars have been shown in vitro to have antioxidant activity, suggesting that RFOs may also act as antioxidants. The RFO pathway also interacts with other carbohydrate pathways, such as that of O‐methyl inositol (OMI), which shows that the functional relevance of RFOs must not be seen in isolation to overall carbon re‐allocation during stress responses.