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Drought is common in most regions of the world, and it has a significant impact on plant growth and development. Plants, on the other hand, have evolved their own defense systems to deal with the extreme weather. The reprogramming of gene expression by microRNAs (miRNAs) is one of these defense mechanisms. miRNAs are short noncoding RNAs that have emerged as key post-transcriptional gene regulators in a variety of species. Drought stress modulates the expression of certain miRNAs that are functionally conserved across plant species. These characteristics imply that miRNA-based genetic changes might improve drought resistance in plants. This study highlights current knowledge of plant miRNA biogenesis, regulatory mechanisms and their role in drought stress responses. miRNAs functions and their adaptations by plants during drought stress has also been explained that can be exploited to promote drought-resistance among economically important crops., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Plants are subjected to salt and drought stresses concurrently but our knowledge about the effects of combined stress on plants is limited, especially on halophytes. We aim to study if some diverse drought and salt tolerance traits in halophyte may explain their tolerance to salinity and drought stresses, individual and in combination, and identify key traits that influence growth under such stress conditions. Here, the halophyte Halogeton glomeratus was grown under control, single or combinations of 60 days drought and salt treatments, and morphophysiological responses were tested. Our results showed that drought, salinity, and combination of these two stressors decreased plant growth (shoot height, root length, and biomass), leaf photosynthetic pigments content (chlorophyll a, b, a + b and carotenoids), gas exchange parameters (Net photosynthesis rate [P N ], transpiration rate [E], stomatal conductance [g s ]), and water potential (ψ w ), and the decreases were more prominent under combined drought and salinity treatment compared with these two stressors individually performed. Similarly, combined drought and salinity treatment induced more severe oxidative stress as indicated by more hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) accumulated. Nevertheless, H. glomeratus is equipped with specific mechanisms to protect itself against drought and salt stresses, including upregulation of superoxide dismutases (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6) activities and accumulation of osmoprotectants (Na + , Cl - , and soluble sugar). Our results indicated that photosynthetic pigments content, gas exchange parameters, water potential, APX activity, CAT activity, soluble sugar, H 2 O 2 , and MDA are valuable screening criteria for drought and salt, alone or combined, and provide the tolerant assessment of H. glomeratus., (© 2021 Scandinavian Plant Physiology Society.)

Groundwater and its associated nutrients sustain the establishment and persistence of phreatophytes. Rapid root elongation immediately after germination is vital for desert species to access deep water sources to avoid water-deficit stress. However, the growth strategy and responses to nutrients and water of young phreatophyte seedlings before their roots reach the water table are poorly understood, especially in the scenarios of nitrogen (N) deposition and drought. We investigated how simulated N deposition and drought affect the plasticity of Alhagi sparsifolia seedlings by multiple eco-physiological mechanisms. Seedlings were planted under drought-stressed or well-watered conditions and subjected to various levels of N addition (0, 3.0, 6.0, or 9.0 gN·m -2  yr -1 ). The amounts of N and water independently or interactively affected the photosynthetic traits, drought tolerance characteristics, morphological traits, biomass allocation strategy, and nutrient distribution patterns among the plant organs. Moreover, changes mediated by N addition at the leaf level reflected the drought acclimation of the seedlings, which may be related to biomass and nutrient partitioning between organs. The roots were found to be more sensitive to variation of the N:phosphorus (P) ratio, and greater proportions of biomass, N, and P were allocated to resource-acquiring organs (i.e., leaves and fine roots) than to other tissues. A. sparsifolia adopts numerous strategies to tolerate drought, and additional N input was crucial to enhance the growth of drought-stressed A. sparsifolia, which was mainly attributable to its positive impact on the N and P uptake capacity mediated by increased biomass allocation to the roots., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Drylands, comprising semi‐arid, arid, and hyperarid regions, cover approximately 41% of the Earth's land surface and have expanded considerably in recent decades. Even under more optimistic scenarios, such as limiting global temperature rise to 1.5°C by 2100, semi‐arid lands may increase by up to 38%. This study provides an overview of the state‐of‐the‐art regarding changing aridity in arid regions, with a specific focus on its effects on the accumulation and availability of carbon (C), nitrogen (N), and phosphorus (P) in plant–soil systems. Additionally, we summarized the impacts of rising aridity on biodiversity, service provisioning, and feedback effects on climate change across scales. The expansion of arid ecosystems is linked to a decline in C and nutrient stocks, plant community biomass and diversity, thereby diminishing the capacity for recovery and maintaining adequate water‐use efficiency by plants and microbes. Prolonged drought led to a −3.3% reduction in soil organic carbon (SOC) content (based on 148 drought‐manipulation studies), a −8.7% decrease in plant litter input, a −13.0% decline in absolute litter decomposition, and a −5.7% decrease in litter decomposition rate. Moreover, a substantial positive feedback loop with global warming exists, primarily due to increased albedo. The loss of critical ecosystem services, including food production capacity and water resources, poses a severe challenge to the inhabitants of these regions. Increased aridity reduces SOC, nutrient, and water content. Aridity expansion and intensification exacerbate socio‐economic disparities between economically rich and least developed countries, with significant opportunities for improvement through substantial investments in infrastructure and technology. By 2100, half the world's landmass may become dryland, characterized by severe conditions marked by limited C, N, and P resources, water scarcity, and substantial loss of native species biodiversity. These conditions pose formidable challenges for maintaining essential services, impacting human well‐being and raising complex global and regional socio‐political challenges. [ABSTRACT FROM AUTHOR]

Traits of leaves and fine roots are expected to predict the responses and adaptation of plants to their environments. Whether and how fine‐root traits (FRTs) are associated with the allocation of foliar phosphorus (P) fractions of desert species in water‐ and P‐poor environments, however, remains unclear. We exposed seedlings of Alhagi sparsifolia Shap. (hereafter Alhagi) treated with two water and four P‐supply levels for three years in open‐air pot experiments and measured the concentrations of foliar P fractions, foliar traits, and FRTs. The allocation proportion of foliar nucleic acid‐P and acid phosphatase (APase) activity of fine roots were significantly higher by 45.94 and 53.3% in drought and no‐P treatments relative to well‐watered and high‐P treatments, whereas foliar metabolic‐P and structural‐P were significantly lower by 3.70 and 5.26%. Allocation proportions of foliar structural‐P and residual‐P were positively correlated with fine‐root P (FRP) concentration, but nucleic acid‐P concentration was negatively correlated with FRP concentration. A tradeoff was found between the allocation proportion to all foliar P fractions relative to the FRP concentration, fine‐root APase activity, and amounts of carboxylates, followed by fine‐root morphological traits. The requirement for a link between the aboveground and underground tissues of Alhagi was generally higher in the drought than the well‐watered treatment. Altering FRTs and the allocation of P to foliar nucleic acid‐P were two coupled strategies of Alhagi under conditions of drought and/or low‐P. These results advance our understanding of the strategies for allocating foliar P by mediating FRTs in drought and P‐poor environments. [ABSTRACT FROM AUTHOR]

Phosphorus (P) limitation and water stress can affect trees' growth, yet differing levels of nutrition under drought may have negative or positive effects on their growth and metabolism. This study aimed to evaluate the impact of P nutrition upon growth and metabolism in drought-stressed Phoebe zhennan (an endangered forest tree species) seedlings, to provide a basis for strengthening its conservation in the face of future climate change. A complete randomized design was used to investigate the effects of four different levels of P fertilization (no P, low P, moderate P, and high P) under water stress on the growth, photosynthesis, and nitrogen metabolism of P. zhennan. Drought-stressed seedlings under high P (HP) application had enhanced growth, while moderate P (MP) application improved their root biomass and leaf area only, whereas low P (LP) did not significantly affect any growth trait. Moreover, HP fertilization had positive effects on leaf relative water contents (LRWCs), while HP and MP both significantly improved photosynthetic traits vis-à-vis non-fertilized seedlings. The concentration of soluble sugars was significantly higher in non-fertilized than fertilized seedlings as were nitrogenous compounds (NO3− and NH4+) and nitrogen metabolic enzymes (NR, GDH, GOGAT, and GS) activities. Both NO3−and NH4+concentrations were significantly decreased under HP application compared with the non-fertilized counterparts. The plant traits improved under HP application counteracted the adverse impact of low nitrate availability and promoted seedling growth. Low-dose fertilization produces depressive effects in P. zhennan, but a high P concentration can overcome those negative effects to improve growth. [ABSTRACT FROM AUTHOR]

• The snow depth (SDmax) and snow cover duration days (SCD) on the TP have decreased significantly from 1980 to 2020. • The shortening of SCD was more related to advanced snow cover melt date (SCM) than to snow cover start date (SCS). • The spatiotemporal variations of snow depth and snow phenology have strong altitude dependence. With an increase in altitude, SCS is earlier, SCM later, SCD longer, and SDmax thicker. • Elevation-dependent warming explains the elevation-dependent decrease of SDmax and SCD. Snowmelt from the Tibetan Plateau (TP) is the water source of many major Asian rivers, with significant importance for regional water supply and ecosystem services. The spatiotemporal variations of snow cover on the TP and its response to climate change at different altitudes are still unclear because of the lack of in situ observations on the western TP, and limitations of optical remote sensing due to clouds. Using a daily passive microwave remote sensing snow depth dataset from 1979 to 2020 across the TP, this study investigates the spatiotemporal variations of snow depth and snow phenology as well as their responses to climate change. The results showed that during the past 40 years, the maximum snow depth (SDmax) and the snow cover duration days (SCD) on the TP decreased significantly at a rate of 0.6 cm/decade and 2.9 d/decade, respectively. The snow cover starting date (SCS) was delayed at a rate of 1.1 d/decade, whereas the snow cover melt date (SCM) advanced at a rate of 1.1 d/decade. The decrease of SCD was driven by the advance of SCM, which was caused by the decrease of SDmax, whereas the decrease of SDmax was driven by the increase in snow accumulation season temperature (Ta). The TP showed significant elevation-dependent warming (EDW) (0.04 ℃ decade-1 km−1) and elevation-dependent decrease of SDmax (0.12 cm decade-1 km−1) and SCD (4.1 d decade-1 km−1). The EDW explains the elevation-dependent decrease of SDmax (r = −0.72, P < 0.05) and SCD (r = −0.83, P < 0.05). It is expected that the negative feedback effect of SDmax and SCD on EDW may further exacerbate the EDW of the TP, and the earlier snowmelt due to the continuous decrease of snow depth may increase the frequency of droughts and floods. Our findings support the enhancement of EDW on the TP, depletion of solid reservoirs, and intensification of the regional water crisis in a warmer future. [ABSTRACT FROM AUTHOR]