On the initiation of jasmonate biosynthesis in wounded leaves
On the initiation of jasmonate biosynthesis in wounded leaves
复制标题
受伤叶片中茉莉酸生物合成的启动
DOI：
10.1093/plphys/kiac163
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发表时间：
2022
期刊：
影响因子：
7.4
通讯作者：
Koo, Abraham J.
中科院分区：
文献类型：
--
作者：
Kimberlin, Athen N.;Holtsclaw, Rebekah E.;Zhang, Tong;Mulaudzi, Takalani;Koo, Abraham J.
植物防御激素茉莉酸(JA)在非胁迫叶片中的基础水平较低，但伤害使其几乎瞬间增加。JA的生物合成是如何启动的还不确定，但产生脂肪酸前体的脂解步骤通常被认为是第一步。在这里，我们使用了一系列的生理学、药理学、遗传学和基因表达动力学分析以及激素谱来证明，在拟南芥(Arabiopsis Thaliana)中，伤害后JA的早期尖峰并不依赖于JA生物合成基因的表达。使用转基因系统，我们展示了如何分离对伤害和JA的反应，阻止受伤叶片中JA的永久合成。然后，我们使用缺陷花药DEHISCENCE1(DAD1)作为伤害反应脂肪酶的模型，证明虽然它在叶片中的瞬时表达可以诱导低水平的JA生物合成，但伤害会触发额外的激活水平，导致JA的大量积累。DAD1介导的JA合成的这种创伤触发的增强效应可以直接发生在受损叶片中，也可以通过系统传递的创伤信号间接发生在未受损的远缘叶片中。损伤、α-亚麻酸和催化位突变对DAD1的蛋白质稳定性有影响。总之，这些数据支持独立于基因转录和翻译的机制，以启动受伤叶片中快速的JA爆发，并展示了如何使用脂肪酶的瞬时表达来揭示关键脂解步骤的活性和稳定性水平上发生的变化。
The basal level of the plant defense hormone jasmonate (JA) in unstressed leaves is low, but wounding causes its near instantaneous increase. How JA biosynthesis is initiated is uncertain, but the lipolysis step that generates fatty acid precursors is generally considered to be the first step. Here, we used a series of physiological, pharmacological, genetic, and kinetic analyses of gene expression and hormone profiling to demonstrate that the early spiking of JA upon wounding does not depend on the expression of JA biosynthetic genes in Arabidopsis (Arabidopsis thaliana). Using a transgenic system, we showed how decoupling the responses to wounding and JA prevents the perpetual synthesis of JA in wounded leaves. We then used DEFECTIVE IN ANTHER DEHISCENCE1 (DAD1) as a model wound-responsive lipase to demonstrate that although its transient expression in leaves can elicit JA biosynthesis to a low level, an additional level of activation is triggered by wounding, which causes massive accumulation of JA. This wound-triggered boosting effect of DAD1-mediated JA synthesis can happen directly in damaged leaves or indirectly in undamaged remote leaves by the systemically transmitted wound signal. Finally, protein stability of DAD1 was influenced by wounding, α-linolenic acid, and mutation in its catalytic site. Together, the data support mechanisms that are independent of gene transcription and translation to initiate the rapid JA burst in wounded leaves and demonstrate how transient expression of the lipase can be used to reveal changes occurring at the level of activity and stability of the key lipolytic step.