Transcriptome-Wide Identification of Novel UV-B- and Light Modulated Flavonol Pathway Genes Controlled by VviMYBF1.
Transcriptome-Wide Identification of Novel UV-B- and Light Modulated Flavonol Pathway Genes Controlled by VviMYBF1.
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DOI：
10.3389/fpls.2017.01084
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发表时间：
2017
影响因子：
5.6
通讯作者：
Bogs J
中科院分区：
文献类型：
--
作者：
Czemmel S;Höll J;Loyola R;Arce-Johnson P;Alcalde JA;Matus JT;Bogs J
黄酮醇是一类在植物中具有重要光保护作用的黄酮类化合物。此外，黄酮醇的含量和组成对果实品质也有很大影响。我们先前已经证明，葡萄R2R3-MYB转录因子(Tf)VviMYBF1通过诱导黄酮醇合成酶(VviFls1/VviFls4)的表达来促进黄酮醇的积累，这是初始黄酮醇途径的关键步骤。尽管如此，葡萄中黄酮醇修饰的基因网络，包括结构基因和调控基因，仍然知之甚少。为了确定黄酮醇修饰基因和作用于VviMYBF1下游的转录因子，以异位表达VviMYBF1或绿色荧光蛋白的葡萄毛状根为对照，进行了基于基因芯片的转录组分析。在VviMYBF1转基因根中诱导出VviFls1，糖基化黄酮醇的积累明显高于对照。在差异表达的基因中，确定了具有预测鼠李糖基转移酶(例如RhaT1)或糖基转移酶(例如GT3)活性的潜在的黄酮醇修饰酶。此外，MYB和bZIP家族的重要转录因子，如原花青素调节子VviMYBPA1和UV-B光响应同源物VviHYH，由于VviMYBF1的过度表达，其表达模式也发生了显著变化。共时表达分析表明，VviMYBF1与VviFls1、VviGT3和VviRhaT1在果实发育过程中以及在田间不同光照和UV-B辐射条件下成熟的果实中呈正相关。这些结果表明，VviMYBF1的过表达导致了黄酮醇途径的新基因的发现，黄酮醇的修饰机制可以受到农业实践的影响，以优化葡萄的黄酮醇组成。
Flavonols constitute a group of flavonoids with important photoprotective roles in plants. In addition, flavonol content and composition greatly influences fruit quality. We previously demonstrated that the grapevine R2R3-MYB transcription factor (TF) VviMYBF1 promotes flavonol accumulation by inducing the expression of flavonol synthase (VviFLS1/VviFLS4), a key step of the initial flavonol pathway. Despite this, gene networks underlying flavonol modification in grapevine including both structural and regulatory genes remain poorly understood. In order to identify flavonol modifying genes and TFs acting downstream of VviMYBF1 a microarray-based transcriptome analysis was performed on grapevine hairy roots ectopically expressing VviMYBF1 or a Green Fluorescent Protein as control. VviFLS1 was induced in VviMYBF1 transgenic roots and glycosylated flavonols accumulated significantly compared with control lines. Among the differentially expressed genes, potential flavonol-modifying enzymes with predicted rhamnosyltransferase (e.g., RhaT1) or glycosyltransferase (e.g., GT3) activities were identified. In addition, important TFs of the MYB and bZIP families such as the proanthocyanidin regulator VviMYBPA1 and the UV-B light responsive HY5 homolog VviHYH were significantly altered in their expression pattern by overexpression of VviMYBF1. Co-temporal expression analysis demonstrated positive correlation of VviMYBF1 with VviFLS1, VviGT3, and VviRhaT1 during berry development and in fruits ripened with different light and UV-B radiation conditions at field. These results show that VviMYBF1 overexpression led to the identification of novel genes of the flavonol pathway and that the flavonol modifying machinery can be influenced by agricultural practices to optimize flavonol composition in grapes.