A bHLH-Type Transcription Factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1, Acts as a Repressor to Negatively Regulate Jasmonate Signaling in Arabidopsis
A bHLH-Type Transcription Factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1, Acts as a Repressor to Negatively Regulate Jasmonate Signaling in Arabidopsis
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DOI：
10.1105/tpc.113.111112
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发表时间：
2013-05-01
期刊：
影响因子：
11.6
通讯作者：
Ohme-Takagi, Masaru
中科院分区：
文献类型：
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作者：
Nakata, Masaru;Mitsuda, Nobutaka;Ohme-Takagi, Masaru
茉莉酸是一类调节植物生长和对生物和非生物胁迫反应之间平衡的植物激素。虽然最近的研究已经揭示了JA诱导的拟南芥反应的机制，植物减弱JA诱导的反应的机制仍然是难以捉摸的。在这里，我们报告了一种碱性螺旋-环-螺旋型转录因子，即ABA诱导的BHLH型转录因子/JA相关MYC 2-LIKE 1（JAM 1），充当转录抑制因子并负调节JA信号传导。表达JAM 1嵌合阻遏物的功能获得性转基因植物表现出JA反应的大幅减少，包括JA诱导的根生长抑制，花青素积累和雄性不育。这些植物在抵抗草食性昆虫甜菜夜蛾（Spodoptera exigua）攻击方面也受到损害。相反，jam 1功能丧失突变体显示出增强的JA反应性，包括增加对昆虫攻击的抗性。JAM 1和MYC 2竞争性结合MYC 2的靶序列，这可能提供了JAM 1负调控JA信号传导和抑制MYC 2功能的机制。这些结果表明，JAM 1负调控JA信号，从而发挥了关键作用，在微调JA介导的胁迫反应和植物生长。
Jasmonates (JAs) are plant hormones that regulate the balance between plant growth and responses to biotic and abiotic stresses. Although recent studies have uncovered the mechanisms for JA-induced responses in Arabidopsis thaliana, the mechanisms by which plants attenuate the JA-induced responses remain elusive. Here, we report that a basic helix-loop-helix-type transcription factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1 (JAM1), acts as a transcriptional repressor and negatively regulates JA signaling. Gain-of-function transgenic plants expressing the chimeric repressor for JAM1 exhibited substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by the insect herbivore Spodoptera exigua. Conversely, jam1 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to insect attack. JAM1 and MYC2 competitively bind to the target sequence of MYC2, which likely provides the mechanism for negative regulation of JA signaling and suppression of MYC2 functions by JAM1. These results indicate that JAM1 negatively regulates JA signaling, thereby playing a pivotal role in fine-tuning of JA-mediated stress responses and plant growth.