Silencing of hydroperoxide lyase and allene oxide synthase reveals substrate and defense signaling crosstalk in Nicotiana attenuata
Silencing of hydroperoxide lyase and allene oxide synthase reveals substrate and defense signaling crosstalk in Nicotiana attenuata
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DOI：
10.1111/j.1365-313x.2004.02185.x
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发表时间：
2004-10-01
期刊：
影响因子：
7.2
通讯作者：
Baldwin, IT
中科院分区：
文献类型：
--
作者：
Halitschke, R;Ziegler, J;Baldwin, IT
茉莉酸（JA）和绿色叶挥发物（GLV）生物合成所需的脂肪酸氢过氧化物（HP）底物由单独的脂氧合酶（LOX）提供。我们通过反义表达烟草内源基因（NaAOS、NaHPL）来沉默LOX下游的两个基因：丙二烯氧化物合成酶（AOS）和HP裂解酶（HPL）的表达，其中JA的生物合成被植食动物特异性激发子扩增。我们报告说，这些激发子也放大伤口诱导的GLV释放，但抑制伤口诱导的增加NaHPL转录，这表明底物通量控制GLV的生物合成。正如预期的那样，NaHPL和NaAOS的沉默分别减少了GLV的释放和JA的积累。令人惊讶的是，HPL和AOS-silenced植物增强了JA和GLV响应，这表明这两个oxylipin级联之间的底物“串扰”。在用天然鳞翅目食草动物进行的选择测试中，具有耗尽的GLV（as-hpl）的植物比野生型（WT）或空载体对照植物的吸引力小。在饲养试验中，天蛾幼虫在as-hpl植物上发育较慢。减少的幼虫消耗和性能，这不是由as-hpl植物中防御反应的增加引起的，可以通过添加合成的GLV恢复到WT水平，表明GLV起到摄食刺激剂的作用。基因表达谱的cDNA微阵列分析和表征的几个诱导防御草食动物引起的as-hpl和as-aos植物揭示了不同的JA和GLVs参与防御信号。挥发性萜类化合物的激发（间接防御）需要JA信号传导，而胰蛋白酶蛋白酶抑制剂的激发（直接防御）需要功能性JA和GLV级联。
The fatty acid hydroperoxide (HP) substrates required for the biosynthesis of jasmonic acid (JA) and green leaf volatiles (GLVs) are supplied by separate lipoxygenases (LOX). We silenced the expression of two genes downstream of the LOX: allene oxide synthase (AOS) and HP lyase (HPL) by antisense expression of endogenous genes (NaAOS, NaHPL) in Nicotiana attenuata, in which the biosynthesis of JA is amplified by herbivore-specific elicitors. We report that these elicitors also amplify wound-induced GLV releases, but suppress the wound-induced increase of NaHPL transcripts, suggesting that substrate flux controls GLV biosynthesis. As expected, silencing of NaHPL and NaAOS reduced GLV release and JA accumulation, respectively. Surprisingly, HPL- and AOS-silenced plants had enhanced JA and GLV responses, suggesting substrate 'crosstalk' between these two oxylipin cascades. Plants with depleted GLVs (as-hpl) were less attractive than wild type (WT) or empty vector control plants in choice-tests with native lepidopteran herbivores. In feeding trials, Manduca sexta larvae developed slower on as-hpl plants. The reduced larval consumption and performance, which was not caused by increases in defense responses in as-hpl plants, could be restored to WT levels by the addition of synthetic GLVs, demonstrating that GLVs function as feeding stimulants. Gene expression profiling by cDNA microarray analysis and characterization of several induced defenses in herbivore-elicited as-hpl and as-aos plants revealed differential involvement of JA and GLVs in defense signaling. Elicitation of volatile terpenoids (an indirect defense) requires JA signaling, where as trypsin protease inhibitor elicitation (a direct defense) requires both functional JA and GLV cascades.