Abstract
The drought stress responses of vascular plants are complex regulatory mechanisms because they include various physiological responses from signal perception under water deficit conditions to the acquisition of drought stress resistance at the whole-plant level. It is thought that plants first recognize water deficit conditions in roots and that several molecular signals then move from roots to shoots. Finally, a phytohormone, abscisic acid (ABA) is synthesized mainly in leaves. However, the detailed molecular mechanisms of stress sensors and the regulators that initiate ABA biosynthesis in response to drought stress conditions are still unclear. Another important issue is how plants adjust ABA propagation, stress-mediated gene expression and metabolite composition to acquire drought stress resistance in different tissues throughout the whole plant. In this review, we summarize recent advances in research on drought stress responses, focusing on long-distance signaling from roots to shoots, ABA synthesis and transport, and metabolic regulation in both cellular and whole-plant levels of Arabidopsis and crops. We also discuss coordinated mechanisms for acquiring drought stress adaptations and resistance via tissue-to-tissue communication and long-distance signaling.
Highlights
Environmental stresses have multiple effects on plant growth
Recent study reported that the CLAVATA3/EMBRYO-SURROUNDING REGION-RELATED25 (CLE25) peptide modulates abscisic acid (ABA) biosynthesis to regulate stomatal closure during root-to-shoot signaling under dehydration stress conditions (Takahashi et al, 2018b)
ATHK1/AHK1 complements the function of SLN1 that encodes osmosensing histidine protein kinase in the yeast, indicating that ATHK1/AHK1 can acts as an osmotic stress sensor
Summary
Environmental stresses have multiple effects on plant growth. Extreme stresses often inflict severe damage during the production of plant biomass. We summarize recent knowledge of how long-distance signaling, ABA transport and metabolic regulation mediate drought stress responses and resistance in Arabidopsis and crops These findings imply that plants have developed unique and complex mechanisms that connect various organs to resist environmental stresses and optimize growth. Recent study reported that the CLE25 peptide modulates ABA biosynthesis to regulate stomatal closure during root-to-shoot signaling under dehydration stress conditions (Takahashi et al, 2018b). The CLE25–BAM1 and BAM3 systems control ABA accumulation and responses, including stomatal closure and stress-inducible gene expression These results indicate that plants can integrate the water deficit information into their roots and leaves and optimize stress adaptations in those tissues. These reports on CLE25 show that the function of CLE25 in the leaves and roots may be advantageous in adaptation to drought stress conditions in higher plants
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