Roles of MicroRNAs in Plant Stress Tolerance

MicroRNAs （miRNAs） are one kind of small RNA in all eukaryote. MicroRNAs can regulate gene expression of eukaryote; they widely participate in every physiological process. They can block mRNA expression or cleave mRNA by complement to target mRNA. Scholars estimate miRNA genes occuping about 1% of genome, but they can regulate 10%-30% genes of whole genome. The genes are regulated by miRNA including signal proteins, enzymes, transcription factors, and so on. In the field of plant research, the start of miRNA research is later, but it is proved that plant miRNAs are important to every plant physiological process. Now miRNA has become the hotspot of plant molecular biology research. This paper introduced the biology function, action mechanism, researching method and recently development of microRNAs, also focused on advances in plant microRNAs. This paper has important reference value for plant stress tolerance miRNA research.

MicroRNAs: The Potential Biomarkers in Plant Stress Response

MicroRNAs (miRNAs) are endogenous small RNA regulatory molecules of approximate 20-24 nucleotides that are involved in regulating the intrinsic growth and development of organs in plants and animals as well as in maintaining the integrity of genomes. Past few years have witnessed an increase in research reports on the crucial role of miRNAs in plant stress response. Plant miRNAs regulate gene expression at the post-transcriptional level not only by suppression of mRNA translation but also by direct cleavage of the target mRNAs. This review starts with a brief overview on small RNAs including miRNAs, biogenesis of miRNA and focuses mainly on the various up and down-regulated plant miRNAs under different biotic and abiotic stresses showing advancement of studies about miRNA and their stress regulation pathway. This review explores the emerging role of miRNAs as potential biomarkers in plant stress responses.

Nitric Oxide(NO) and Plant Stress

In depth study of NO reveals that NO is a bioactive molecule that exerts a number of roles in many physiological and pathological process.NO is produced in response to drought,salinity,temperature shock and pathogen attack.NO rapidly reacts with ROS,ABA and other hormones and directly or indirectly regulate ethylene biosynthesis.The authors review the response of between plant NO and kinds of stresses,and possible mechanism was discussed.

Physiological Response of the Resurrection Fern Subjected to Environmental Stress as Shown by Plant Cell Membrane Integrity

Resurrection fern has a unique ability to maintain cell wall integrity when the plant cell is desiccated. It uses proteins such as late embryogenesis proteins and heat shock proteins to maintain their cellular functions. The purpose of this experiment is to determine the effects of environmental stressors on the physiological response of the resurrection fern (Pleopeltis polypodioides). The physiological response of resurrection fern plants was subjected to various temperatures (-50°C, 0°C, 25°C, and 50°C) for 7 days. Results indicated that there was a significant difference between hydrated and desiccated ferns based on the temperature. Additionally, electrolyte leakage measurements confirmed cell damage following exposure to temperature extremes of -50°C and 50°C.

Phytohormones and their metabolic engineering for abiotic stress tolerance in crop plants

Abiotic stresses including drought,salinity,heat,cold,flooding,and ultraviolet radiation causes crop losses worldwide.In recent times,preventing these crop losses and producing more food and feed to meet the demands of ever-increasing human populations have gained unprecedented importance.However,the proportion of agricultural lands facing multiple abiotic stresses is expected only to rise under a changing global climate fueled by anthropogenic activities.Identifying the mechanisms developed and deployed by plants to counteract abiotic stresses and maintain their growth and survival under harsh conditions thus holds great significance.Recent investigations have shown that phytohormones,including the classical auxins,cytokinins,ethylene,and gibberellins,and newer members including brassinosteroids,jasmonates,and strigolactones may prove to be important metabolic engineering targets for producing abiotic stress-tolerant crop plants.In this review,we summarize and critically assess the roles that phytohormones play in plant growth and development and abiotic stress tolerance,besides their engineering for conferring abiotic stress tolerance in transgenic crops.We also describe recent successes in identifying the roles of phytohormones under stressful conditions.We conclude by describing the recent progress and future prospects including limitations and challenges of phytohormone engineering for inducing abiotic stress tolerance in crop plants.

Oxidative Stress and Role of Natural Plant Derived Antioxidants in Animal Reproduction

The experimental knowledge on the role of oxidative stress,and beneficial and detrimental effects of plant derived antioxidants in male and female animal reproduction are reviewed in this article.Free radical-induced oxidative stress in animal reproduction causes great loss to livestock industry.Antioxidant therapy has been implicated to be effective in preventing diseases resulted from oxidative stress.Considering the advantages of lower side effects of natural antioxidants than those of synthetic antioxidants,plants or their extracts have been extensively utilized in animals.Although many advances have been gained on application of plant derived antioxidants in alleviating oxidative stress,debatable issues still exist.Because many opposite effects were observed even using plant extracts containing similar bioactive substances in the same animal species.Therefore,plant derived antioxidants,like free radicals,are ＂double-edged swords＂ in animal reproduction,representing that they may exhibit beneficial or detrimental effects in animal reproduction,including spermatogenesis,semen functions,estrous cycles,ovulation,ovary functions,endometrium,embryo development,and pregnancy.Besides dose-dependent manner as an explanation of plant extracts＇ dual function,future studies are needed to investigate the mechanism of double-edged actions of plant derived antioxidants in different animal reproduction systems.

Identification of the Regulator of G-Protein Signaling Protein Responsive to Plant Hormones and Abiotic Stresses in Brassica napus

Regulator of G protein signaling proteins （RGS） accelerate the rate of GTP hydrolysis by Gαproteins, thus acting as negative regulators of G-protein signaling. Studies on Arabidopsis and soybean have proven that RGS proteins are physiologically important in plants and contribute to the signaling pathways regulated by different stimuli. Brassica napus is an important agriculturally relevant plant, the wildly planted oilseed rape in the world, which possesses an identiifed Gα, Gβand Gγsubunits. In the present study, we identiifed and characterized a Brassica napus RGS gene, BnRGS1, which contained an open reading frame of 1 380 bp encoding a putative 52.6 kDa polypeptide of 459 amino acids, within seven putative transmembrane domains in the N-terminal and RGS box in the C-terminal. BnRGS1 is located on the membrane in onion epidermal cells and tobacco leaves, and interacts with BnGA1 in the mating-based split-ubiquitin system. The expression levels of BnRGS1 were quite different in different tissues and developmental stages, and induced by abscisic acid （ABA） and indole-3-acetic acid （IAA）. The effects of gibberellin （GA3） and brassinolide （BR） on the expression of BnRGS1 were irregular under the concentrations tested. Moreover, the transcript level of BnRGS1 was also induced by polyethylene glycol （PEG）, whereas remained little changed by 200 mmol L-1 NaCl. These results suggested that the BnRGS1 may be involved in B. napus response to plant hormone signaling and abiotic stresses.

Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillsid

Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang) orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15×8m^2 and separated by 2m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positive ecological effects on citrus orchard ecosystem stability.

Salinity Stress Alleviation by Foliar Bio-Stimulant, Proline and Potassium Nutrition Promotes Growth and Yield Quality of Garlic Plant

Soil salinity is one of the major yield-limiting factors for crop production in many agricultural regions all over the world. Besides following efficient management practices at the field scale to reduce accumulation of salts in the effective root-zone, the effective use of treatments to alleviate the effects of salinity stress and improve crop salt tolerance is a promising solution to ensure crop production in such adverse conditions. A field experiment was carried out to investigate the effect of foliar spray with plant-based biostimulant (i.e. with and/or without 3% yeast extract), three levels of proline (0, 25, and 50 mM), and combined with potassium fertilizers, as potassium sulfate, 48% K2O (0, 50, and 100 kg/fed.) on growth promotion, chemical composition of garlic leaves, bulb quality parameters as well as yield and its components of garlic plant grown under moderate saline soil. Results revealed that the interaction between foliar spray with yeast extract at 3% and proline at 50 mM combined with proper K level at 100 kg/fed., was the best interaction treatment for increasing vegetative growth parameters, i.e. plant height, number of leaves per plant, and mineral contents (N, P, K, S, Ca and Mg in leaves), and proline content of garlic leaves after 135 days from planting time, total yield/fed., and garlic yield quality parameters at harvesting time. In conclusion, the detrimental effects of salinity stress can be alleviated by stress tolerance-inducing compounds, such as yeast extract and proline with proper application rate of K fertilization during the growing season of garlic crop.

Omics Studies and Systems Biology Perspective towards Abiotic Stress Response in Plants

Plant abiotic stress responses are vital yield-restricting aspect in agriculture. Recent technology in plant biology allows research of such stress responses at a molecular scale in plants. Network analysis provides in-depth knowledge regarding omics information visualisation as it reduces the intrinsic intricacy of such data. The use of integrated functional genomics helps to understand the relationship between the genomic profile and the phenotypic profile in different environmental conditions of an organism. Plants’ responses to abiotic stress are often considered as a complex process. Systems biology approaches allow visualising and understanding how plant life works to overcome abiotic stress. The combination of integrated functional genomics along with bioinformatics will put a hand in additional in-depth research knowledge on stress tolerance to plants by exploiting available genetic information and continuously improving techniques and strategies. Most of the omics technologies are high throughput with very rapid data generation rates and humongous outputs. These technologies have made noticeable contributions to the modern-day improvements in our knowledge of plant biology. So, in this review, omics studies and the system biology approach towards abiotic stress tolerance in plants are highlighted.

RNAi Mediated Drought and Salinity Stress Tolerance in Plants

RNAi mediated gene silencing demonstrated to serve as a defence mechanism against abiotic stress. Some endogenous small RNAs (microRNA and siRNA) have emerged as important players in plant abiotic stress response. Drought and salinity are the major environmental stresses that limit the agricultural food production. miRNA involved in drought and salinity stress response, including ABA response, auxin signalling, osmoprotection and antioxidant defence by downregulating the response target gene. It is observed that some of the microRNAs are upregulated or downregulated in response to drought and salt stress. We reviewed that miR167, miR393, mir474, miR169g are upregulated whereas miR168, miR396, miR397 are downregulated in rice plant during drought stress. Moreover, our detail categorical analysis on the basis of mechanism of action found that miRNA involved in drought stress was 28% in ABA signalling and response, 14.2% in auxin signalling, 9.52% in miRNA processing, 14.2% in cell growth, 9.52% in antioxidant defence, 4.76% in CO2 fixation and 9.52% in osmotic adjustment. Similarly, miRNA involved in salinity stress was 5.8% in auxin signalling, 23.5% in vegetative phase change and root, shoot, leaf and vascular development, 11.76% in gynoecium and stamens development, 8.82% in metabolic adaptation, 2.74% in early embryogenesis and 41.17% not known. Importantly, some common miRNAs such as miR159, miR167, miR169, miR393 and miR397 play an important role in both drought and salinity stress conditions. Here, in this review, we mainly focused on the current status of miRNAs, mechanism of action and their regulatory network during drought and salinity stress in plants.

Leaf Responses of Micropropagated Apple Plants to Water Stress:Changes in Endogenous Hormones and Their Influence on Carbohydrate Metabolism

The changes in the concentrations of endogenous hormones and their influence on carbohydrate metabolism in leaves of micropropagated Fuji apple plants were studied under water deficiency stress. The results showed that water stress induced a rapid increase in the concentration of abscisic acid （ABA） and led to a decrease in concentrations of both zeatin and gibberellins （GAs）. The concentration of indole-3-acetic acid （IAA） changed in an independent manner, which was not correlated with the different levels of water stress. With regard to the carbohydrates, the contents of sorbitol and sucrose increased, whereas the content of starch decreased. The increase in the concentration of ABA was significantly correlated with both the increase in the activity of aldose-6-phosphate reductase （A6PR） and the decrease in the activity of sorbitol dehydrogenase （SDH）, indicating that ABA played a regulatory role in sorbitol metabolism. The concentration of ABA was positively correlated to the activity of sucrose-phosphate synthase （SPS） but negatively correlated to the activities of acid invertase （AI） and ADP-glucose-pyrophosphorylase （ADPGppase） in water-stressed plants, which indicated that ABA promoted sucrose synthesis and inhibited sucrose degradation and starch synthesis at the same time. Under conditions of water stress, the decrease in the level of zeatin was accompanied by a decrease in the activities of SDH and ADPGPPase. GAs concentration showed positive correlation with ADPGPPase activity. IAA showed no significant correlation with any of the enzymes tested in this study. The results of this study suggested that ABA might be one of the key factors regulating the distribution of carbohydrates under water stress. The metabolism of sorbitol and starch under conditions of water stress might be regulated by the combined action of many plant hormones.

Response of 14C-Salicylic Acid to Heat Stress After Being Fed to Leaves of Grape Plants

An experiment was conducted to investigate the response of salicylic acid as a second messenger to the heat stress in grape plants. For this purpose, all leaves of grape (Vitis vinifera×V. labrussa L. cv. Jingxiu) plants were removed except the 3rd, 4th, 5th, 6th, and 7th ones. The 5th leaf was fed with C-SA, and the 4th and 6th leaves were exposed to high 14 temperature at 40±0.5°C. It was observed that more C-SA transported out from the 5th leaf and the distribution of C-SA 14 14 in each organ of plant altered in response to heat stress. The accumulation of C-SA in both the 4th and 6th leaves being 14 exposed to high temperature was at least three times higher than that in control. The distribution of C-SA in other distal 14 leaves (the 3rd and 7th leaf) decreased, but more C-SA accumulated in stems adjacent to the 4th or 6th leaf exposed to 14 high temperature. In addition, there was more C-SA being transported upwards or downwards while the 4th and 6th 14 leaves were exposed to high temperature respectively. Therefore, our results suggested that SA was closely involved in signal transduction of heat stress in grape plants. However, the ratio of C radioactivity assayed after SA being extracted 14 to that of direct assay with apparatus was more than 70%, which indicated about 30% C was lost or catabolized during 14 transportation.

Research Progress and Prospect on the Effects of Abiotic Stress on Plant Photosynthesis

Photosynthesis is the basis of plant growth and development as well as the existence of the biological world. Photosynthesis is of great theoretical and practical significance. In this paper, the effects of temperature, drought, salt, light and other abiotic stress factors on plant photosynthesis were reviewed.

Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India

Rhizobia are vital for nitrogen input, fertility of soil and legume plant growth. Knowledge on rhizobial diversity from arid and semiarid areas is important for dry land agriculture in the context of climatic change and for economic utilization. This study provides morphological, biochemical, stress tolerance and plant growth promoting characteristics of fifteen rhizobial isolates from the nodules of same number of wild legumes and one isolate from cultivated Arachis hypogea from semi-arid region, Tirupati. The bacterial isolates were confirmed as rhizobia based on colony morphology and biochemical tests. Based on the colour change of YMA-BTB medium, eight isolates were identified as slow growers and six were fast growers. The isolates differed in growth pattern, colony morphology, antibiotic resistance at higher concentrations and uniformity in utilization of carbon and nitrogen sources. The isolates are tolerant to NaCl up to one percent, displayed normal growth at temperatures 28℃ - 30℃, at neutral pH and poor growth at pH 5and 9. The isolates varied in the production of EPS and IAA, positive for phosphate solubilization and siderophore formation. This functional diversity displayed by the isolates can be utilised for the legume crop production by cross inoculation.

An Analysis of the Correlation between the Changes in Sa-tellite DNA Methylation Patterns and Plant Cell Responses to the Stress

The differences in satellite DNA methylation pattern of corn seedlings with various spontaneous chromosome aberration yields and changes in methylation pattern of these DNA sequences under different exposure modes of acute UV-C and chronic gamma-irradiations have been investigated. The obtained experimental data and the conducted correlation analysis demonstrated the significant correlation between the satellite DNA methylation pattern varieties and chromosome aberration yields under various stress exposure modes. The role of satellite DNA methylation pattern variability and its changing in key responses to stress such as mobile elements’ activation, cell’s passage of checkpoints, and homological repair was discussed.

集成化设计中SmartPlant 3D与CAESARⅡ的工作流整合

SmartPlant 3D是新一代的工厂设计软件,而CAESARⅡ是压力管道应力分析专业软件。文章基于建设数字化工厂的集成化设计理念,利用SmartPlant 3D生成的管道组件数据文件和CAESARⅡ创建的管道关系数据库文件,定制开发符合工程设计需要的数据流格式,探索了如何建立SmartPlant 3D与CAESARⅡ的数据双向传递;优化专业间工作流程,实现集成化设计的目标。并对相关细节进行了探讨。

EFFECTS OF TURBULENT SHEAR STRESS ON THE GROWTH OF SUSPENDED PLANT CELLN IN A BUBBLE COLUMN REACTOR

In this paper,effects of increasing the height of column,bubble size and gas flow rate onthe growth of suspended Catharanthus roseus plant cells in a 1.5 litre bubble column were studied.Statistical characteristics of turbulence such as auto-correlation function,and auto-power spectral den-sity function of the nuctuating liquid velocity were measured in a bubble column employing pseudo-cell-granulated agar.Calculations of turbulent shear stress were carried out.From these studies it is sug-gested that in plant cell suspension culture sparged with large bubbles.turbulent shear stress is prob-ably one of the most important reasons for the inhibited cell growth and cell damage.Larger bubblesor higher gas flow rates lead to the increase in shear stress and are more detrimental to plant cells.

Promising Actions of Certain Medicinal Plants of Bangladesh against Diabetes and Oxidative Stress: A Review

Diabetes is a metabolic illness defined by hyperglycemia that affects 10% of the world’s population. Diabetic complications such as blindness, kidney failure, and heart failure can develop if left untreated and are made worse by oxidative stress. Oxidative stress contributes to the rise of diabetic complications, particularly type-2 diabetes. In the blood vessels of diabetic individuals, it causes endothelial dysfunction. Diabetes is one of the leading causes of death worldwide. Nowadays, it is alarming that the number of diabetic patients is increasing dramatically. There are plenty of anti-diabetic drugs available on the market, but they possess several adverse effects and do not completely cure diabetes. It has now become a financial burden on patients, their families, and society as well. Medicinal plants have gained popularity in developed and developing countries over the last two decades because of their vast natural sources and lack of harmful effects compared to modern allopathic medications. According to the World Health Organization, traditional medicines, which are mostly manufactured from plants, are still used by 80% of the population in developing countries for the management and curing of diseases. This review includes 81 Bangladeshi medicinal plants from 51 different families that can be used to treat diabetes and oxidative stress. Among them, Psidium guajava (L.), Aloe vera, Catharanthus roseus, Allium sativum, Annona squamosa, Cinnamon zeylaniucm, Amaranthus esculentus, Eugenia jambolana, Azadirachta indica, Moringa oleifera, Spondias pinnata, Coccinia grandis (L.), Momordica charantia L., Heretiera fomes, Trigonella foenum-graecum were most potent. The fundamental purpose of our study is to find out and highlight certain medicinal plants in Bangladesh that have anti-diabetic and antioxidant capabilities so that the researchers can develop newer anti-diabetic medications with minimal side effects to treat metabolic dysfunction, diabetic complications, and oxidative stress more effectively.

Effect of mixed-cropping and water-stress on macro-nutrients and biochemical constituents of rhizomatous medicinal plants in Central Himalaya,India

Plants in the alpine zone mainly depend on the reserved food materials stored in their rhizomes for the next growing season. We investigated the effect of mixed cropping （Phaseolus vulgaris L. var. Pinto） with four rhizomatous medicinal plants, i.e., Angelica glauca, Arnebia benthamii, Rheum emodi and Pleurospermum angelicoides as well as three levels of water stress treatment under two conditions （shade net and open field） on macronutrients （NPK） and biochemicals （carbohydrates and protein）. The experiment was conducted by completely randomized design （CDR）. The data were analyzed with ANOVA as well as CDR. The experimental results show that in all the species shade conditions with sever water stress （SSWS） increased the level of macronutrients （NPK）. However, （N） concentration was highest under shade with mixed cropping （SMIX）. Under SMIX, carbohydrate content was highest than open field control conditions （CONT）. This investigation results demon- strate that mixed cropping of medicinal plants with Phaseolus vulgaris could be a good livelihood option in the mountainous regions of Indian Central Himalaya. And the water-stress conditions along with mixed cropping could improve the biochemical constituents in the rhizome of these species.