Comprehensive Influences of Overexpression of a MYB Transcriptor Regulating Anthocyanin Biosynthesis on Transcriptome and Metabolome of Tobacco Leaves.

Overexpression of R2R3-MYB transcriptor can induce up-expression of anthocyanin biosynthesis structural genes, and improve the anthocyanin content in plant tissues, but it is not clear whether the MYB transcription factor overexpression does effect on other genes transcript and chemical compounds accumulation. In this manuscript, RNA-sequencing and the stepwise multiple ion monitoring-enhanced product ions (stepwise MIM-EPI) strategy were employed to evaluate the comprehensive effect of the MYB transcription factor in tobacco. Overexpression of could promote anthocyanin accumulation in a lot of tissues of tobacco cultivar Samsun. Only 185 unigenes express differently in a total of 160,965 unigenes in leaves, and 224 chemical compounds were differently accumulated. Three anthocyanins, apigeninidin chloride, pelargonidin 3-O-beta-D-glucoside and cyanidin 3,5-O-diglucoside, were detected only in transgenic lines, which could explain the phenotype of purple leaves. Except for anthocyanins, the phenylpropanoid, polyphenol (catechin), flavonoid, flavone and flavonol, belong to the same subgroups of flavonoids biosynthesis pathway with anthocyanin and were also up-accumulated. Overexpression of activated the bHLH (basic helix-loop-helix protein) transcription factor , relative to anthocyanin biosynthesis and the MYB transcription factor , relative to proanthocyanin biosynthesis. Then, the structural genes, relative to the phenylpropanoid pathway, were activated, which led to the up-accumulation of phenylpropanoid, polyphenol (catechin), flavonoid, flavone, flavonol and anthocyanin. The MYB transcription factor , negative to anthocyanin biosynthesis, also induced up-expression in transgenic lines, which implied that a negative regulation mechanism existed in the anthocyanin biosynthesis pathway. The relative contents of all 19 differently accumulated amino and derivers were decreased in transgenic lines, which meant the phenylalanine biosynthesis pathway completed the same substrates with other amino acids. Interestingly, the acetylalkylglycerol acetylhydrolase was down-expressed in transgenic lines, which caused 19 lyso-phosphatidylcholine and derivatives of lipids to be up-accumulated, and 8 octodecane and derivatives were down-accumulated. This research will give more information about the function of MYB transcription factors on the anthocyanin biosynthesis and other chemical compounds and be of benefit to obtaining new plant cultivars with high anthocyanin content by biotechnology.