Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea.
PLoS One. 2013;8(2):e55482. doi: 10.1371/journal.pone.0055482. Epub 2013 Feb 5.
Jasmonates (JAs) are important regulators of plant biotic and abiotic stress responses and development. AtJMT in Arabidopsis thaliana and BcNTR1 in Brassica campestris encode jasmonic acid carboxyl methyltransferases, which catalyze methyl jasmonate (MeJA) biosynthesis and are involved in JA signaling. Their expression is induced by MeJA application. To understand its regulatory mechanism, here we define a novel JA-responsive cis-element (JARE), G(C)TCCTGA, in the AtJMT and BcNTR1 promoters, by promoter deletion analysis and Yeast 1-Hybrid (Y1H) assays; the JARE is distinct from other JA-responsive cis-elements previously reported. We also used Y1H screening to identify a trans-acting factor, AtBBD1, which binds to the JARE and interacts with AtJAZ1 and AtJAZ4. Knockout and overexpression analyses showed that AtBBD1 and its close homologue AtBBD2 are functionally redundant and act as negative regulators of AtJMT expression. However, AtBBD1 positively regulated the JA-responsive expression of JR2. Chromatin immunoprecipitation from knockout and overexpression plants revealed that repression of AtJMT is associated with reduced histone acetylation in the promoter region containing the JARE. These results show that AtBBD1 interacts with JAZ proteins, binds to the JARE and represses AtJMT expression.
茉莉酸（JAs）是植物生物和非生物胁迫反应和发育的重要调节剂。拟南芥中的 JMT 和油菜中的 BcNTR1 编码茉莉酸羧基甲基转移酶，它们催化甲基茉莉酸（MeJA）的生物合成，并参与 JA 信号转导。它们的表达受 MeJA 处理的诱导。为了理解其调控机制，我们通过启动子缺失分析和酵母 1-杂交（Y1H）实验，在 AtJMT 和 BcNTR1 启动子中定义了一个新的茉莉酸反应顺式元件（JARE），G（C）TCCTGA；该 JARE 与以前报道的其他茉莉酸反应顺式元件不同。我们还使用 Y1H 筛选鉴定了一个反式作用因子 AtBBD1，它与 JARE 结合，并与 AtJAZ1 和 AtJAZ4 相互作用。敲除和过表达分析表明，AtBBD1 和其近同源物 AtBBD2 功能上是冗余的，并作为 AtJMT 表达的负调控因子。然而，AtBBD1 正向调控 JR2 的 JA 反应性表达。敲除和过表达植物的染色质免疫沉淀显示，AtJMT 的抑制与包含 JARE 的启动子区域中组蛋白乙酰化的减少有关。这些结果表明，AtBBD1 与 JAZ 蛋白相互作用，结合 JARE 并抑制 AtJMT 表达。
