Functional characterization of a new grapevine MYB transcription factor and regulation of proanthocyanidin biosynthesis in grapes
Functional characterization of a new grapevine MYB transcription factor and regulation of proanthocyanidin biosynthesis in grapes
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DOI：
10.1093/jxb/eru213
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发表时间：
2014-08-01
影响因子：
6.9
通讯作者：
Tanaka, Nobukazu
中科院分区：
文献类型：
--
作者：
Koyama, Kazuya;Numata, Mineyo;Tanaka, Nobukazu
采用改良的基因表达系列分析（SuperSAGE）方法，筛选出不同光照条件下与葡萄原花青素（PA）积累协调表达的基因，发现了一个新的PA生物合成调控因子。该R2 R3-MYB转录因子VvMYBPAR与PA生物合成调节植物MYB（如VvMYBPA 2和TRANSPARENT TESTA 2）显示出高度的蛋白质序列相似性。它的转录水平相对较高的年轻浆果的皮肤，而水平较高的种子，并在veraison左右的最大值。除了对改良的光照条件的反应外，该基因还对培养浆果的表皮中脱落酸的应用做出了反应。在PA特异性分支基因中，该转录谱与VvANR和VvLAR 1的转录谱不相关，但与VvLAR 2的转录谱密切相关，表明PA特异性分支基因与已知PA调节因子VvMYBPA 2的调节不同。VvMYBPAR的PA特异性调节通过拟南芥中的VvMYBPAR组成型表达得到证实，其中转基因特异性诱导PA生物合成基因，并导致在蔗糖补充培养基上生长的植物中PA积累以诱导花青素苷合成。利用葡萄藤细胞进行的瞬时报告基因分析表明，VvMYBPAR激活了PA特异性分支基因和与单体PA前体的修饰和转运相关的候选基因上的启动子，以及常见类黄酮途径中的VvCHS 3和VvF 3 '5'Hd的启动子，但不激活花青素特异性分支上的VvUFGT的启动子。这个新的因子表明PA生物合成的多基因调控密切相关的MYB转录因子在葡萄。
A new regulator of proanthocyanidin (PA) biosynthesis in grapes was found by screening genes coordinately expressed with PA accumulation under different light conditions using a substantially improved method of serial analysis of gene expression (SuperSAGE). This R2R3-MYB transcription factor, VvMYBPAR, shows high protein sequence similarity with PA biosynthesis-regulating plant MYBs, such as VvMYBPA2 and TRANSPARENT TESTA2. Its transcript levels were relatively high in the skins of young berries, whereas the levels were higher in the seeds and at a maximum around veraison. In addition to its response to modified light conditions, the gene responded to abscisic acid application in the skins of cultured berries. Among the PA-specific branch genes, this transcript profile was not correlated with that of VvANR and VvLAR1 but was closely related to that of VvLAR2, suggesting different regulation of PA-specific branch genes from that of a known PA regulator, VvMYBPA2. The PA-specific regulation of VvMYBPAR was confirmed by VvMYBPAR constitutive expression in Arabidopsis in which the transgene specifically induced PA biosynthetic genes and resulted in PA accumulation in plants grown on sucrose-supplemented media to induce anthocyanin synthesis. A transient reporter assay using grapevine cells showed that VvMYBPAR activated the promoters on PA-specific branch genes and candidate genes associated with modification and transport of monomeric PA precursors, as well as the promoters of VvCHS3 and VvF3'5'Hd in the common flavonoid pathway, but not that of VvUFGT on the anthocyanin-specific branch. This new factor suggests the polygenic regulation of PA biosynthesis in grapes by closely related MYB transcription factors.