The Institute of Enology and Viticulture, University of Yamanashi, Kofu, Yamanashi, Japan.
PLoS One. 2011;6(6):e21308. doi: 10.1371/journal.pone.0021308. Epub 2011 Jun 17.
We report here that pink grape berries were obtained by a short insertion in the intron of the MybA1 gene, a gene that regulates grape berry color. Genetic variation was detected among the MybA1 genes from grapes cultivated worldwide. PCR analysis of the MybA1 gene demonstrated that the size of the MybA1 gene in the red allele differs among grapes. Oriental V. vinifera bearing pink berries has the longest MybA1 gene among grapes, whereas the shortest MybA1 gene was detected in occidental V. vinifera grapes. The nucleotide sequences of the MybA1 genes demonstrated that oriental V. vinifera has two additional gene fragments (44 bp and 111 bp) in the promoter region of the MybA1 gene in the red allele and another 33 bp fragment in the second intron of the MybA1 gene in the red allele. The short insertion in the intron decreased the transcription activity in the model system and retained MybA1 transcripts with unspliced intron in the total RNA. From the experiments using deletion mutants of the 33 bp short insertion, 16 bp of the 3' end in the insertion is a key structure for a defect in splicing of MybA1 transcripts. Thus, a weakly colored grape berry might be a result of the short insertion in the intron of a color regulatory gene. This is new evidence concerning the molecular mechanism of the fate of grape berry color. These findings are expected to contribute to the further understanding of the color variation in grape berries, which is correlated with the evolutional events occurring in the MybA1 gene of grapes.
我们在此报告，通过在调控葡萄浆果颜色的 MybA1 基因的内含子中进行短插入，获得了粉红色葡萄浆果。在世界各地栽培的葡萄中，MybA1 基因存在遗传变异。MybA1 基因的 PCR 分析表明，红色等位基因中 MybA1 基因的大小在葡萄中有所不同。具有粉红色浆果的东方 V. vinifera 在葡萄中具有最长的 MybA1 基因，而西方 V. vinifera 葡萄中检测到最短的 MybA1 基因。MybA1 基因的核苷酸序列表明，东方 V. vinifera 在红色等位基因的 MybA1 基因启动子区域中具有两个额外的基因片段（44 bp 和 111 bp），而在红色等位基因的 MybA1 基因的第二个内含子中具有另一个 33 bp 片段。内含子中的短插入降低了模型系统中的转录活性，并在总 RNA 中保留了带有未剪接内含子的 MybA1 转录物。使用 33 bp 短插入缺失突变体的实验表明，插入 3' 端的 16 bp 是 MybA1 转录物剪接缺陷的关键结构。因此，颜色较浅的葡萄浆果可能是由于颜色调控基因内含子中的短插入所致。这是关于葡萄浆果颜色命运的分子机制的新证据。这些发现有望进一步了解与葡萄 MybA1 基因中发生的进化事件相关的葡萄浆果颜色的变化。
