MYB5-TPS31/ANR cascades regulate the transcription of cannabinoid and proanthocyanidin under saline-alkali stress

Rose (Rosa rugosa) petals are rich in diverse secondary metabolites, which have important physiological functions as well as great economic values. Currently, it remains unclear how saline and/or alkaline stress(es) influence the accumulation of secondary metabolites in rose. In this study, we analyzed the transcriptome and metabolite profiles of rose petals under aline-alkali stress and uncovered the induction mechanism underlying major metabolites. Dramatic changes were observed in the expression of 1363 genes and the abundances of 196 metabolites in response to saline-alkali stress. These differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) are mainly associated with flavonoid and terpenoid metabolism and the reconstruction of cell walls. Of them, TERPENE SYNTHASE 31 (TPS31) overexpression in tobacco leaves driven by its own promoter resulted in a significant reduction in the abundances of many terpenoids, which were differentially influenced by saline-alkali stress. An integrated analysis of metabolomic and transcriptomic data revealed a high correlation between the abundances of flavonoids/terpenoids and the expression of the transcription factor MYB5. MYB5 may orchestrate cannabinoid and proanthocyanidins synthesis through direct regulation of TPS31 and ANR expression under aline-alkali stress. Our finding facilitates improving the bioactive substance accumulation and breeding of varieties for metabolic engineering.