Overexpression of CsMYB90 enhances anthocyanin accumulation and alters metabolic pathways in transgenic tobacco

MYB transcription factors play pivotal roles in anthocyanin biosynthesis and its regulatory network. In this study, CsMYB90 was cloned and heterologously expressed in tobacco (Nicotiana tabacum cv. K326), followed by systematic functional validation through integrated phenotypic, transcriptomic, and metabolomic analyses. The results showed that transgenic tobacco leaves exhibited a striking purple phenotype, with anthocyanin accumulation reached 13.04-fold higher than wild-type control. CsMYB90 significantly elevated the levels of anthocyanin pigments, specifically delphinidin-3-O-rhamnoside (783.14 µg/g) and cyanidin-3-O-glucoside (209.40 µg/g), by promoting the expression of key structural genes such as dihydroflavonol reductase (DFR), chalcone isomerase (CHI), and phenylalanine ammonia-lyase (PAL) thereby inducing the purple phenotype. Furthermore, we preliminarily confirmed that CsMYB90 has transcriptional activation activity on the downstream gene NtDFR1 of anthocyanins, and the overexpression of CsMYB90 enhanced the cold tolerance of transgenic tobacco. These findings enrich the theoretical basis of MYBs regulation of anthocyanins, and provide data support for the application of CsMYB90 in plant anthocyanin regulation molecular breeding.