Key Laboratory of Adaptation and Evolution of Plateau Biota (AEPB), Northwest Institute of Plateau Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Xining 810008, China.
Qinghai Province Key Laboratory of Crop Molecular Breeding, Xining 810008, China.
Int J Mol Sci. 2019 Oct 16;20(20):5123. doi: 10.3390/ijms20205123.
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.
R2R3-MYB 转录因子的过表达可以诱导花色苷生物合成结构基因的上调表达，从而提高植物组织中的花色苷含量，但 MYB 转录因子的过表达是否会影响其他基因的转录和化学化合物的积累尚不清楚。在本手稿中，我们采用 RNA 测序和逐步多重离子监测增强产物离子（stepwise MIM-EPI）策略来评估 MYB 转录因子在烟草中的综合效应。在烟草品种 Samsun 的许多组织中，过表达 可以促进花色苷的积累。在叶片中，总共有 160965 个基因中，只有 185 个基因表达不同，224 种化学化合物的积累也不同。只有在转基因系中检测到 3 种花色苷，即芹菜素氯化物、天竺葵苷 3-O-β-D-葡萄糖苷和矢车菊素 3,5-O-二葡萄糖苷，这可以解释紫色叶片的表型。除花色苷外，苯丙素、多酚（儿茶素）、类黄酮、黄酮和黄烷醇也属于花色苷生物合成途径的同一亚组，也被上调积累。与花色苷生物合成和 MYB 转录因子相对应，过表达 激活了 bHLH（碱性螺旋-环-螺旋蛋白）转录因子 。然后，与苯丙素途径相对应的结构基因被激活，导致苯丙素、多酚（儿茶素）、类黄酮、黄酮、黄烷醇和花色苷的积累增加。花色苷生物合成途径的负调控机制也存在，与花色苷生物合成负相关的 MYB 转录因子 也在转基因系中诱导表达上调。在转基因系中，所有 19 种不同积累的氨基酸及其衍生物的相对含量均降低，这意味着苯丙氨酸生物合成途径与其他氨基酸完成了相同的底物。有趣的是，在转基因系中乙酰基甘油乙酰水解酶下调表达，导致 19 种溶血磷脂酰胆碱及其衍生物的积累增加，8 种辛烷及其衍生物的积累减少。这项研究将为 MYB 转录因子在花色苷生物合成和其他化学化合物中的功能提供更多信息，并有助于通过生物技术获得具有高花色苷含量的新植物品种。
