Regulation of Jasmonate-Induced Leaf Senescence by Antagonism between bHLH Subgroup IIIe and IIId Factors in Arabidopsis
Regulation of Jasmonate-Induced Leaf Senescence by Antagonism between bHLH Subgroup IIIe and IIId Factors in Arabidopsis
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拟南芥中 bHLH 亚组 IIIe 和 IIId 因子之间的拮抗作用对茉莉酸诱导的叶片衰老的调节
DOI：
10.1105/tpc.15.00110
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发表时间：
2015-06-01
期刊：
影响因子：
11.6
通讯作者：
Xie, Daoxin
中科院分区：
文献类型：
--
作者：
Qi, Tiancong;Wang, Jiaojiao;Xie, Daoxin
BHLHIIe因子MYC2、MYC3和MYC4冗余地干预JA诱导的叶片衰老，而IIID因子bHLH03、bHLH13、bHLH14和bHLH17拮抗IIIe因子。植物启动叶片衰老，将衰老的叶片中的营养和能量重新分配到发育中的组织或储存器官中，用于生长、繁殖和防御。叶片衰老是叶片发育的最后阶段，受各种环境胁迫、发育线索和内源激素信号的调节。茉莉酸(JA)是植物防御和发育所必需的一种脂类植物激素，是激活衰老相关基因表达和诱导叶片衰老的重要内源信号。这项研究揭示了茉莉酸诱导叶片衰老的机制之一：bHLHIIIe亚组因子MYC2、MYC3和MYC4与bHLHIIID因子bHLH03、bHLH13、bHLH14和bHLH17的拮抗作用。结果表明，MYC2、MYC3和MYC4在激活茉莉酸诱导的叶片衰老过程中具有冗余功能。MYC2结合并激活其靶基因SAG29(衰老相关基因GENE29)的启动子，从而激活茉莉酸诱导的叶片衰老。有趣的是，植物已经进化出一种复杂的反馈调节机制来调节JA诱导的叶片衰老：bHLH亚组IIID因子(bHLH03、bHLH13、bHLH14和bHLH17)与SAG29的启动子结合并抑制其表达，以减弱MYC2/MYC3/MYC4激活的JA诱导的叶片衰老。激活剂和抑制子的拮抗调节将在适宜的水平上介导茉莉酸诱导的叶片衰老，使植物在波动的环境条件下存活。
The bHLH subgroup IIIe factors MYC2, MYC3, and MYC4 redundantly meditate JA-induced leaf senescence; the subgroup IIId factors bHLH03, bHLH13, bHLH14, and bHLH17 antagonize the subgroup IIIe factors. Plants initiate leaf senescence to relocate nutrients and energy from aging leaves to developing tissues or storage organs for growth, reproduction, and defense. Leaf senescence, the final stage of leaf development, is regulated by various environmental stresses, developmental cues, and endogenous hormone signals. Jasmonate (JA), a lipid-derived phytohormone essential for plant defense and plant development, serves as an important endogenous signal to activate senescence-associated gene expression and induce leaf senescence. This study revealed one of the mechanisms underlying JA-induced leaf senescence: antagonistic interactions of the bHLH subgroup IIIe factors MYC2, MYC3, and MYC4 with the bHLH subgroup IIId factors bHLH03, bHLH13, bHLH14, and bHLH17. We showed that MYC2, MYC3, and MYC4 function redundantly to activate JA-induced leaf senescence. MYC2 binds to and activates the promoter of its target gene SAG29 (SENESCENCE-ASSOCIATED GENE29) to activate JA-induced leaf senescence. Interestingly, plants have evolved an elaborate feedback regulation mechanism to modulate JA-induced leaf senescence: The bHLH subgroup IIId factors (bHLH03, bHLH13, bHLH14, and bHLH17) bind to the promoter of SAG29 and repress its expression to attenuate MYC2/MYC3/MYC4-activated JA-induced leaf senescence. The antagonistic regulation by activators and repressors would mediate JA-induced leaf senescence at proper level suitable for plant survival in fluctuating environmental conditions.