Tobacco MYC2 Regulates Jasmonate-Inducible Nicotine Biosynthesis Genes Directly and By Way of the NIC2-Locus ERF Genes
Tobacco MYC2 Regulates Jasmonate-Inducible Nicotine Biosynthesis Genes Directly and By Way of the NIC2-Locus ERF Genes
复制标题
DOI：
10.1093/pcp/pcr063
复制
发表时间：
2011-06-01
影响因子：
4.9
通讯作者：
Hashimoto, Takashi
中科院分区：
文献类型：
--
作者：
Shoji, Tsubasa;Hashimoto, Takashi
在拟南芥中，MYC2家族的碱性螺旋 - 环 - 螺旋转录因子介导茉莉酸响应基因的转录调控，并且它们的转录活性因与茉莉酸 - ZIM结构域（JAZ）蛋白的物理相互作用而受到抑制。烟草属植物中茉莉酸诱导的尼古丁形成已被证明受到烟草JAZ蛋白的抑制，并受MYC2相关和NIC2位点乙烯响应因子（ERF）转录因子的调控。在此我们表明，烟草MYC2（NtMYC2）识别在几个尼古丁生物合成基因的近端启动子区域中发现的G - 盒序列，5'-CAC(G/A)T(G/T)-3'，这些基因包括腐胺N - 甲基转移酶2（PMT2）和喹啉酸磷酸核糖转移酶2（QPT2）。利用培养的烟草细胞进行的瞬时反式激活实验表明，NtMYC2和NIC2位点的ERF189根据其相应的结合位点累加激活PMT2和QPT2启动子。在烟草毛状根中对NtMYC2进行RNA干扰（RNAi）沉默，强烈降低了茉莉酸响应结构基因（包括那些参与尼古丁生物合成的基因）以及NIC2位点ERF基因的转录水平。相反，ERF189对于NtMYC2的表达不是必需的。在酵母双杂交实验中，NtMYC2（而非ERF189）与烟草JAZ蛋白相互作用。这些结果表明，NtMYC2通过两种组合方式控制尼古丁生物合成基因，即直接结合靶启动子中的G - 盒以及上调NIC2位点的ERF基因。
In Arabidopsis, the MYC2-family basic helix-loop-helix transcription factors mediate transcriptional regulation of jasmonate-responsive genes, and their transcriptional activities are suppressed by physical interactions with jasmonate-ZIM domain (JAZ) proteins. Jasmonate-inducible nicotine formation in Nicotiana plants has been shown to be suppressed by tobacco JAZ proteins, and be regulated by both MYC2-related and NIC2-locus ethylene response factor (ERF) transcription factors. We here show that tobacco MYC2 (NtMYC2) recognizes the G-box sequences, 5'-CAC(G/A)T(G/T)-3', found in the proximal promoter regions of several nicotine biosynthesis genes, including Putrescine N-Methyltransferase 2 (PMT2) and Quinolinate Phosphoribosyltransferase 2 (QPT2). Transient transactivation assays using cultured tobacco cells showed that NtMYC2 and NIC2-locus ERF189 additively activated the PMT2 and QPT2 promoters depending on their cognate binding sites. RNA interference (RNAi) silencing of NtMYC2 in tobacco hairy roots strongly decreased transcript levels of jasmonate-responsive structural genes, including those involved in nicotine biosynthesis, as well as the NIC2-locus ERF genes. Conversely, ERF189 was not required for the expression of NtMYC2. NtMYC2, but not ERF189, interacted with tobacoo JAZs in a yeast two-hybrid assay. These results indicate that NtMYC2 controls nicotine biosynthesis genes in two combinatorial ways, by directly binding the G-box in the target promoters and by up-regulating the NIC2-locus ERF genes.