A gain-of-function allele of TPC1 activates oxylipin biogenesis after leaf wounding in Arabidopsis
A gain-of-function allele of TPC1 activates oxylipin biogenesis after leaf wounding in Arabidopsis
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DOI：
10.1111/j.1365-313x.2006.03002.x
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发表时间：
2007-03-01
期刊：
影响因子：
7.2
通讯作者：
Farmer, Edward E.
中科院分区：
文献类型：
--
作者：
Bonaventure, Gustavo;Gfeller, Aurelie;Farmer, Edward E.
茉莉酸是植物防御基因表达的有效脂质介质，在受伤后迅速合成。这些脂质介质也通过正反馈回路刺激其自身的产生，这取决于JA合成和JA信号传导。到目前为止，调控茉莉酸生物合成及其反馈回路激活的分子组分的特征很差。我们采用了能够检测13-脂氧合酶的误调节活性的遗传筛选，该酶在茉莉酸生物合成途径的入口点起作用。拟南芥fou 2（脂肪酸加氧上调2）突变体的叶提取物显示出增加的能力，催化合成脂氧合酶（LOX）代谢产物。定量氧脂蛋白分析确定了不到两倍增加茉莉酸水平在健康的fou 2叶相比，野生型，然而，受伤的fou 2叶强烈增加茉莉酸生物合成相比，受伤的野生型。此外，植物对真菌灰葡萄孢的抗性增强。fou 2突变体中比野生型更高的LOX活性和增强的抗性完全依赖于功能性茉莉酸响应途径。fou 2突变体在双孔通道1基因（TPC 1）的推定电压传感器中携带错义突变，该基因编码Ca 2+渗透性非选择性阳离子通道。fou 2液泡膜的膜片钳分析显示，与野生型相比，在较低的膜电位下，突变通道具有更快的时间依赖性电导率和激活。结果表明，阳离子通量施加强有力的控制，从而JA刺激自己的合成的正反馈回路。
Jasmonates, potent lipid mediators of defense gene expression in plants, are rapidly synthesized in response to wounding. These lipid mediators also stimulate their own production via a positive feedback circuit, which depends on both JA synthesis and JA signaling. To date, molecular components regulating the activation of jasmonate biogenesis and its feedback loop have been poorly characterized. We employed a genetic screen capable of detecting the misregulated activity of 13-lipoxygenase, which operates at the entry point of the jasmonate biosynthesis pathway. Leaf extracts from the Arabidopsis fou2 (fatty acid oxygenation upregulated 2) mutant displayed an increased capacity to catalyze the synthesis of lipoxygenase (LOX) metabolites. Quantitative oxylipin analysis identified less than twofold increased jasmonate levels in healthy fou2 leaves compared to wild-type; however, wounded fou2 leaves strongly increased jasmonate biogenesis compared to wounded wild-type. Furthermore, the plants displayed enhanced resistance to the fungus Botrytis cinerea. Higher than wild-type LOX activity and enhanced resistance in the fou2 mutant depend fully on a functional jasmonate response pathway. The fou2 mutant carries a missense mutation in the putative voltage sensor of the Two Pore Channel 1 gene (TPC1), which encodes a Ca2+-permeant non-selective cation channel. Patch-clamp analysis of fou2 vacuolar membranes showed faster time-dependent conductivity and activation of the mutated channel at lower membrane potentials than wild-type. The results indicate that cation fluxes exert strong control over the positive feedback loop whereby JA stimulates its own synthesis.