Plants being sessile organisms are often exposed to various abiotic stress conditions, which greatly hamper the growth, yields as well as the quality of produce. Plants respond to abiotic stresses in an exceptionally complex and coordinated manner, involving the interactions and crosstalk with many metabolic-molecular pathways. One of the most common responses is generation of reactive chemical species including reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive carbonyl species (RCS) and reactive sulfur species (RSS). ROS and RNS have long attracted attention from the plant researchers for both their damaging as well as protective effects. However, several reports are emerging to confirm similar roles played by the relatively newer 'reactive' members, the RCS and RSS. Plant reactive species are also hailed as vivacious signaling molecules that play regulatory roles in many plant metabolic procedures. Undeniably, these reactive species are involved in virtually all aspects of plant cell functions. Reactive species and the antioxidant machinery maintain a delicate but critical cellular redox-balance which gets disturbed under stress conditions, where their biosynthesis, transportation, scavenging and the overall metabolism gets decisive for plant survival. The current review aims to highlight and discuss the role of ROS, RNS, RCS, and RSS in plants especially under abiotic stresses, cross-talks between them, current approaches and technological advents for their characterization, and a perspective view on exploration/manipulation of the pathways and check-points involved in biosynthesis, transport and scavenging of these reactive species for engineering abiotic stress tolerant crop plants.
相似文献In this recent era, several approaches have been developed to alleviate the adverse effects of salinity stress in different plants. However, some of them are not eco-friendly. In this context, evolving sustainable approaches which enhance the productivity of saline soil without harming the environment are necessary. Many recent studies showed that plant growth-promoting rhizobacteria (PGPR) are known to confer salinity tolerance to plants. Salt-stressed plants inoculated with PGPR enhance the growth and productivity of crops by reducing oxidative damage, maintaining ionic homeostasis, enhancing antioxidant machinery, and regulating gene expressions. The PGPR also regulates the photosynthetic attributes such as net photosynthetic rate, chlorophyll, and carotenoid contents and enhances the salinity tolerance to plants. Moreover, PGPR has a great role in the enhancement of phytohormones and secondary metabolites synthesis in plants under salt stress. This review summarizes the current reports of the application of PGPR in plants under salt stress and discusses the PGPR-mediated mechanisms in plants of salt tolerance. This review also discusses the potential role of PGPR in cross-talk with phytohormones and secondary metabolites to alleviate salt stress and highlights the research gaps where further research is needed.
相似文献Heat stress (HS) seriously affects crop growth, causing significant crop yield losses worldwide. The regulatory mechanisms controlling HS tolerance in plants are not well understood. Phytohormones are important molecules for coordinating myriad of phenomena related to plant growth and development. They are also essential endogenous signaling molecules that actively mediate numerous physiological responses under abiotic stress by triggering stress-responsive regulatory genes involved in plant growth. This review updates the central role of various phytohormones—indole acetic acid, gibberellic acid, abscisic acid, cytokinins, ethylene, salicylic acid, brassinosteroids, strigolactone, and jasmonic acid—in regulating the HS response so that plants can adapt to increasing temperature stress. We also reveal how these stress-responsive phytohormones switch on various regulatory gene(s) and genes encoding antioxidants and heat shock proteins (HSPs) to combat HS in various plant species.
相似文献Heavy metal (HM) contamination of the environment is a serious threat to sustainable crop production. Among the HMs, chromium (Cr) is one of the most toxic HMs that is known to negatively affect growth and metabolic activities of diverse crop plants. The present study was designed to investigate the ameliorative role of 5-aminolevulinic acid (ALA) under Cr stress in two maize (Zea mays L.) cultivars showing differential sensitivity to Cr tolerance. ALA is a biosynthesis precursor and it has a dominant regulatory effect related to physiological, respiratory, and photosynthesis processes in various plant species. Three concentrations of Cr (0, 5, and 10 mg kg−1) were tested under the graded levels of ALA application (0, 12.5, and 25 mg L−1). The results indicated that Cr stress differentially reduced plant growth attributes, gas exchange characteristics, photosynthetic pigments, and biomass in both the cultivars. Oxidative stress increased as evidenced in the form of electrolyte leakage, malondialdehyde, and hydrogen peroxide (H2O2) accumulation in plants. The anti-oxidative enzyme activities, that is, catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) both in the leaves and roots of maize cultivars decreased due to Cr stress. The concentration of Cr increased in roots and shoots of maize under Cr levels without ALA. Under Cr stress, ALA exogenous application markedly enhanced plant growth, photosynthetic pigments, gas exchange capacity, and biomass. Furthermore, ALA application decreased the Cr-induced oxidative stress in maize cultivars by improving the activities of CAT, POD, and SOD in plants. After ALA application, the Cr concentrations and total Cr uptake by plants differently decreased in both cultivars. The 6103 cultivar of maize was found to be a tolerant cultivar against Cr stress due to its strong defensive system with a higher rate of antioxidant enzyme activities. On the other hand, the other maize cultivar (9108) was found to be a sensitive cultivar against Cr stress due to its weak defense system with higher contents of reactive oxygen species. These findings suggest that ALA can play a regulatory role in maintaining optimum plant growth and efficient photosynthetic processes under Cr-challenged habitats in maize. Thus, ALA application may be used as a sustainable remedial strategy to alleviate Cr-induced stress in maize cultivars.
相似文献Significance and Impact of the Study
Increasing human populations demand more crop yield for food security while crop production is adversely affected by abiotic stresses like drought, salinity and high temperature. Development of stress tolerance in plants is a strategy to cope with the negative effects of adverse environmental conditions. Endophytes are well recognized for plant growth promotion and production of natural compounds. The property of endophytes to induce stress tolerance in plants can be applied to increase crop yields. With this review, we intend to promote application of endophytes in biotechnology and genetic engineering for the development of stress‐tolerant plants. 相似文献Low temperature in later spring severely limits plant growth and causes considerable yield loss in wheat. In this study, the impacts of exogenous salicylic acid (SA) on plant growth, grain yield and key physiological parameters of wheat plants were investigated under field low-temperature conditions using a field air temperature control system (FATC). The results showed that low-temperature stress significantly decreased leaf net photosynthetic rate, plant height and biomass production of wheat plants at the jointing stage, resulting in a reduction in grain yield. Moreover, the growth period of wheat plants was prolonged by low-temperature stress. However, SA-treated plants significantly improved the photochemical efficiency of photosystem II, accumulation of osmo-protectants, activities of enzymatic antioxidants, and pool of non-enzymatic low molecular substances compared with non-SA-treated plants under low-temperature stress. Pretreatment with SA effectively alleviated low-temperature-induced reduction in leaf net photosynthetic rate, plant height, biomass production and grain yield as well as prolonging of growth period of wheat plants. However, SA-treated plants had no significant effects on the expression levels of cold-responsive genes compared with non-SA-treated plants under low-temperature stress. Our results demonstrated that exogenous application of SA is an appropriate strategy for wheat to resist late spring low-temperature stress under field conditions.
相似文献Adverse effects caused by inadequate magnesium (Mg) supply (deficiency or excess) often cause oxidative stress in chloroplasts and a decline in photosynthetic activity. However, 24-epibrassinolide (EBR) is a natural, biodegradable, and ecologically viable plant growth regulator with multiple roles in plant metabolism. This research aims to determine whether the foliar application of EBR (1) can delay chlorophyll degradation and/or (2) mitigate oxidative stress on the photosynthetic process in magnesium-stressed soybean plants. The experiment followed a completely randomized factorial design with two concentrations of 24-epibrassinolide (0 and 0.1 mM EBR, described as – EBR and?+?EBR, respectively) and three Mg supplies (0.0225, 2.25 and 225 mM Mg, described as low, control and high supply of Mg). Inadequate Mg supplies (deficiency and excess) negatively interfered with photosynthetic pigments, chlorophyll fluorescence and gas exchange. However, exogenous EBR sprayed in plants under high Mg maximized superoxide dismutase (37%), catalase (34%), ascorbate peroxidase (48%) and peroxidase (49%), protecting against oxidative stress and delaying chlorophyll degradation. Concomitantly, plants sprayed with this steroid had increases in Mg content, improving the photochemical efficiency and gas exchange because Mg plays an essential role during the light capture process.
相似文献