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Coronatine (COR) is a phytotoxin produced by Pseudomonas syringae and is a functional analogue of the bioactive hormone JA-Ile, which is widely involved in plant defence responses. In this study, we explored the effects of exogenous applications of COR on tobacco plants under polyethylene glycol-induced drought stress. Compared with control (CK), COR-treated tobacco plants exhibited higher leaf relative water content and better photosynthetic performance under drought exposure. Ultrastructural examination revealed that drought led to stomatal closure and disorganization of granum stacking in the chloroplasts (with obvious accumulation of plastoglobuli), and mitochondria in the CK samples presented injured cristae. In the leaf tissue of the COR-treated plants, regularly stacked granum thylakoids, few plastoglobuli and intact mitochondrial membranes and cristae were observed. Totals of 1803 and 6207 differentially expressed genes (DEGs) were identified between the samples from the COR-treated and CK plants under well-watered and drought conditions. Functional annotation analysis revealed that these DEGs were involved mainly in plant hormone signal transduction, cellular carbohydrate metabolic processes and photosynthesis processes. Six hundred forty transcription factor genes were also identified among the DEGs. This study provides a global view of COR-induced drought stress tolerance in tobacco from both physiological and transcriptional aspects. [ABSTRACT FROM AUTHOR]

Coronatine (COR) is a phytotoxin produced by Pseudomonas syringae. Its structure is similar to Jasmonates, which play a number of diverse roles in plant defense. Both have the COI1 plant receptor, so coronatine can manipulate plant hormone signaling to access nutrients and counteract defense responses. In addition to the hormone system, coronatine affects plant nitrogenous metabolism and chloroplast ultrastructure. In this study, we first examined a typical nitrogen-losing phenotype, and used the polyacrylamide gel approach to demonstrate soluble total protein patterns in a time-course experiment under different temperature conditions. We then employed dimensional gel electrophoresis technology (2-DE) and MALDI-TOF-MS to sequester and identify the sensitive proteins. We found a total of 27 coronatine sensitive proteins, 22 of which were located in the chloroplast and 6 of which were directly involved in photosynthesis. Finally, we measured levels of chlorophyll and photosynthetic performance to reveal the phenotypic effect of these proteins. Taken together, these results demonstrated that coronatine enhanced heat tolerance by regulating nitrogenous metabolism and chloroplast ultrastructure to maintain photosynthetic performance and reduce yield loss under heat stress. [ABSTRACT FROM AUTHOR]