drought resistance
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Abstract Background Drought has become the major abiotic stress that causes losses in rice yields and consequently is one of the main environmental factors threatening food security. Long non-coding RNA (lncRNA) is known to play an important role in plant response to drought stress, while the mechanisms of competing endogenous RNA (ceRNA) in drought resistance in upland rice have been rarely reported. Results In our study, a total of 191 lncRNAs, 2115 mRNAs and 32 miRNAs (microRNAs) were found by strand-specific sequencing and small RNA sequencing to be differentially expressed in drought-stressed rice. Functional analysis of results indicate that they play important roles in hormone signal transduction, chlorophyll synthesis, protein synthesis and other pathways. Construction of a ceRNA network revealed that MSTRG.28732.3 may interact with miR171 in the chlorophyll biosynthesis pathway and affect the ability of plants to withstand drought stress by regulating Os02g0662700, Os02g0663100 and Os06g0105350. The accuracy of the regulatory network was verified by qRT-PCR. Conclusion Our results provide a theoretical basis for future studies on the potential function of lncRNA in plant drought resistance, and they provide new genetic resources for drought-resistant rice breeding.

In the past and present, human activities have been involved in triggering global warming, causing drought stresses that affect animals and plants. Plants are more defenseless against drought stress; and therefore, plant development and productive output are decreased. To decrease the effect of drought stress on plants, it is crucial to establish a plant feedback mechanism of resistance to drought. The drought reflex mechanisms include the physical stature physiology and biochemical, cellular, and molecular-based processes. Briefly, improving the root system, leaf structure, osmotic-balance, comparative water contents and stomatal adjustment are considered as most prominent features against drought resistance in crop plants. In addition, the signal transduction pathway and reactive clearance of oxygen are crucial mechanisms for coping with drought stress via calcium and phytohormones such as abscisic acid, salicylic acid, jasmonic acid, auxin, gibberellin, ethylene, brassinosteroids and peptide molecules. Furthermore, microorganisms, such as fungal and bacterial organisms, play a vital role in increasing resistance against drought stress in plants. The number of characteristic loci, transgenic methods and the application of exogenous substances [nitric oxide, (C28H48O6) 24-epibrassinolide, proline, and glycine betaine] are also equally important for enhancing the drought resistance of plants. In a nutshell, the current review will mainly focus on the role of phytohormones and related mechanisms involved in drought tolerance in various crop plants.

AbstractDrought is the main abiotic stress that negatively affects the crop yield. Due to the rapid climate change, actual plant defence mechanisms may be less effective against increased drought stress and other related or co-occurring abiotic stresses such as salt and high temperature. Thus, genetic engineering approaches may be an important tool for improving drought tolerance in crops. This mini-review focuses on the responses to drought stress of the woody crop species Olea europaea and Citrus sp., selecting in particular five main strategies adopted by plants in response to drought stress: aquaporin (AQPs) expression, antioxidant activity, ABA signalling, and trehalose and proline accumulation. Transgenic studies on both the herbaceous Arabidopsis and woody Populus plant models showed an improvement in drought resistance with increasing expression of these drought-inducible genes. Outcomes from the present study suggest the overexpression of the gene families associated with AQPs and ABA biosynthesis, mainly involved in regulating water transport and in preventing water loss, respectively, as candidate targets for improving drought resistance; antioxidants-, trehalose- and proline-related genes remain valid candidates for resistance to a wider spectrum of abiotic stressors, including drought. However, the contribution of an increased stiffness of the modulus elasticity of leaf parenchyma cell walls to the rapid recovery of leaf water potential, delaying by this way the stress onset, is not a secondary aspect of the transgenic optimization, in particular for Olea cultivars.

Drylands are expected to be affected by greater global drought variability in the future; consequently, how dryland ecosystems respond to drought events needs urgent attention. In this study, the Normalized Vegetation Index (NDVI) and Standardized Precipitation and Evaporation Index (SPEI) were employed to quantify the resistance of ecosystem productivity to drought events in drylands of northern China between 1982 and 2015. The relationships and temporal trends of resistance and drought characteristics, which included length, severity, and interval, were examined. The temporal trends of resistance responded greatest to those of drought length, and drought length was the most sensitive and had the strongest negative effect with respect to resistance. Resistance decreased with increasing drought length and did not recover with decreasing drought length in hyper-arid regions after 2004, but did recover in arid and semi-arid regions from 2004 and in dry sub-humid regions from 1997. We reason that the regional differences in resistance may result from the seed bank and compensatory effects of plant species under drought events. In particular, this study implies that the ecosystem productivity of hyper-arid regions is the most vulnerable to drought events, and the drought–resistance and drought–recovery interactions are likely to respond abnormally or even shift under ongoing drought change.

Abstract The frequency and intensity of drought events are increasing with warming climate, which has resulted in worldwide forest mortality. Previous studies have reached a general consensus on the size-dependency of forest resistance to drought, but further understanding at a local scale remains ambiguous with conflicting evidence. In this study, we assessed the impact of canopy height on forest drought resistance in the broadleaf deciduous forest of southwestern China for the 2010 extreme drought event using linear regression and a random forest model. Drought condition was quantified with SPEI (standardized precipitation evapotranspiration index) and drought resistance was measured with the ratio of NDVI (normalized difference vegetation index) during (i.e. 2010) and before (i.e. 2009) the drought. At the regional scale we found that 1) drought resistance of taller canopies (30m and up) declined drastically more than that of canopies with lower height under extreme drought (SPEI < -2); 2). Random forest model showed that the importance of canopy height increased from 17.08% to 20.05% with the increase of drought intensities from no drought to extreme drought. Our results suggest that canopy structure plays a significant role in forest resistance to extreme drought, which has a broad range of implications in forest modeling and resource management.

Abstract Background Compared with other abiotic stresses, drought stress causes serious crop yield reductions. Poly-γ-glutamic acid (γ-PGA), as an environmentally friendly biomacromolecule, plays an important role in plant growth and regulation. Results In this project, the effect of exogenous application of γ-PGA on drought tolerance of maize (Zea mays. L) and its mechanism were studied. Drought dramatically inhibited the growth and development of maize, but the exogenous application of γ-PGA significantly increased the dry weight of maize, the contents of ABA, soluble sugar, proline, and chlorophyll, and the photosynthetic rate under severe drought stress. RNA-seq data showed that γ-PGA may enhance drought resistance in maize by affecting the expression of ABA biosynthesis, signal transduction, and photosynthesis-related genes and other stress-responsive genes, which was also confirmed by RT–PCR and promoter motif analysis. In addition, diversity and structure analysis of the rhizosphere soil bacterial community demonstrated that γ-PGA enriched plant growth promoting bacteria such as Actinobacteria, Chloroflexi, Firmicutes, Alphaproteobacteria and Deltaproteobacteria. Moreover, γ-PGA significantly improved root development, urease activity and the ABA contents of maize rhizospheric soil under drought stress. This study emphasized the possibility of using γ-PGA to improve crop drought resistance and the soil environment under drought conditions and revealed its preliminary mechanism. Conclusions Exogenous application of poly-γ-glutamic acid could significantly enhance the drought resistance of maize by improving photosynthesis, and root development and affecting the rhizosphere microbial community.

Abstract. The purpose of the research is the reaction of spring soft wheat varieties to dry phenomena during the growing season in the forest-steppe zone of the Trans-Urals. Methods. The material was 24 varieties of various biotypes for maturation from the nursery of the competitive variety testing of the Kurgan Research Institute of Agricultural Sciences. Results. The negative effect of the drought reduced the yield in the experiments by 11.9 c/ha, the weight of 1000 grains by 5.7 g, and the nature by 19.7 g/l. The influence of grain size on the yield both in favorable years and in years of drought was noted (r = 0.63…0.98). In arid conditions, vitreous is correlated with yield, 1000 grain weight, in kind, to a lesser extent with gluten content, bread volume, and “flour strength”. The lack of moisture during the grain filling period increased the gluten content by 3.4 %, the quality by 15.1 e. p. IDC, the flour strength by 102.7 e. a., the volume of bread by 106 g/l. In favorable years, the weight of 1000 grains and the vitreous content of the grain correlate with gluten (r = 0.44; r = 0.24–0.84). Indicators of productivity and physical properties of grain increase when sowing at the optimal time, with a certain decrease in the gluten content (by 1.2 %), flour strength (by 5.3 e. a.), bread volume (by 73.2 e. p.). In the early sowing period, moisture deficiency reduces the indicators for all varieties Under these conditions, early-maturing varieties form a larger grain both when sowing at an early time (29.0 g) and when sowing at the optimal (31.3 g). In a drought, the role of the variety is especially high. High drought resistance was shown by the Zauralochka variety of the Kurgan Research Institute of Agriculture, which successfully passed the test in the dry years (2012, 2020) in the GSI system and in the environmental test (KASIB). The yield of the drought-resistant variety Zauralochka on average for the HSU was 20.2 c/ha, exceeding the standard Hercules by 2.2 c/ha. Scientific novelty. The features of the influence of dry phenomena on the yield and the main indicators of the quality of varieties are revealed, the correlation between them is determined. According to drought resistance, a variety of spring soft wheat Zauralochka was selected.