Physiological and transcriptomic analyses of the effects of coronatine on drought tolerance in Carex leucochlora

Drought is an important factor limiting plant growth, development, and productivity. Recently, coronatine (COR) has emerged as a mimic of jasmonates, which play diverse roles in plant tolerance to multiple stressors. Although COR affects the response to drought stress in Carex leucochlora seedlings, the mechanism by which it acts is unclear. We characterized the acclimation of C. leucochlora to drought stress using plant growth, osmotic adjustment, photosynthetic parameters, antioxidant enzyme system and comparative transcriptomics analyses during stress treatments, COR (0.1 nmol L-1) was applied under soil water stress (20 +/- 5%) in the growth chamber. Drought stress strongly suppressed biomass accumulation and loss of cellular water content, inhibited photosynthesis, and damaged cellular membranes in the seedlings. Conversely, COR treatment improved the detrimental effects of drought stress by restoring leaf morphology, alleviating damage to the cell membrane, and improving photosynthetic efficiency and water use efficiency. In addition, COR enhanced the activities of su-peroxide dismutase, peroxidase activity, catalase, and ascorbate peroxidase. There were 1205 transcripts (36.7%) that were common with COR application uniquely induced by drought stress. COR regulated transcription factors from 48 families such as AP2/ERF-ERFs, bHLHs, bZIPs, and C2H2s, and the genes were mainly involved in starch and sucrose metabolism, phenylpropanoid biosynthesis, and plant hormone signal transduction. Taken together, these results provide the physiological mechanism underlying improved drought resistance in C. leucochlora in the presence of COR and provide a new perspective for gene function analysis in COR-mediated signaling pathways. In addition, these findings provide new guidance strategies for the application of COR to improve drought management systems in C. leucochlora establishment and management.