The Arabidopsis TT2 gene encodes an R2R3 MYB domain protein that acts as a key determinant for proanthocyanidin accumulation in developing seed
The Arabidopsis TT2 gene encodes an R2R3 MYB domain protein that acts as a key determinant for proanthocyanidin accumulation in developing seed
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DOI：
10.1105/tpc.13.9.2099
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发表时间：
2001-09-01
期刊：
影响因子：
11.6
通讯作者：
Lepiniec, L
中科院分区：
文献类型：
--
作者：
Nesi, N;Jond, C;Lepiniec, L
在拟南芥中，原花青素在早期种子发育期间特异性地积累在内皮中。至少有三个透明种皮（TT）基因，TT 2，TT 8和TTG 1，是必需的几个类黄酮结构基因在未成熟种子中的正常表达，如二氢黄酮醇-4-还原酶和BANYULS（BAN）。TTS和TTG 1的特点是最近被发现编码一个基本的螺旋-环-螺旋结构域转录因子和WD-重复含有蛋白质，分别。本研究通过T-DNA标签法克隆了TT 2基因。TT 2基因编码一个R2 R3 MYB结构域蛋白，与水稻OsMYB 3蛋白和玉米COLORLESS 1因子具有高度相似性。TT 2-绿色荧光蛋白融合蛋白主要位于细胞核中，与天然TT 2蛋白的调节功能一致。TT 2的表达仅限于种子在早期胚胎发生，与BAN的表达和原花青素的沉积概况一致。最后，在功能获得性实验中，TT 2能够在功能性TT 8蛋白存在下诱导幼苗和根中BAN的异位表达。因此，我们的研究结果强烈表明，严格的空间和时间BAN表达，从而原花青素的积累，至少部分地由TT 2。
In Arabidopsis, proanthocyanidins specifically accumulate in the endothelium during early seed development. At least three TRANSPARENT TESTA (TT) genes, TT2, TT8, and TTG1, are necessary for the normal expression of several flavonoid structural genes in immature seed, such as DIHYDROFLAVONOL-4-REDUCTASE and BANYULS (BAN). TTS and TTG1 were characterized recently and found to code for a basic helix-loop-helix domain transcription factor and a WD-repeat-containing protein, respectively. Here the molecular cloning of the TT2 gene was achieved by T-DNA tagging. TT2 encoded an R2R3 MYB domain protein with high similarity to the rice OsMYB3 protein and the maize COLORLESS1 factor. A TT2-green fluorescent protein fusion protein was located mostly in the nucleus, in agreement with the regulatory function of the native TT2 protein. TT2 expression was restricted to the seed during early embryogenesis, consistent with BAN expression and the proanthocyanidin deposition profile. Finally, in gain-of-function experiments, TT2 was able to induce ectopic expression of BAN in young seedlings and roots in the presence of a functional TT8 protein. Therefore, our results strongly suggest that stringent spatial and temporal BAN expression, and thus proanthocyanidin accumulation, are determined at least partially by TT2.