A knock-out mutation in allene oxide synthase results in male sterility and defective wound signal transduction in Arabidopsis due to a block in jasmonic acid biosynthesis
A knock-out mutation in allene oxide synthase results in male sterility and defective wound signal transduction in Arabidopsis due to a block in jasmonic acid biosynthesis
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DOI：
10.1046/j.1365-313x.2002.01328.x
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发表时间：
2002-07-01
期刊：
影响因子：
7.2
通讯作者：
Feyereisen, R
中科院分区：
文献类型：
--
作者：
Park, JH;Halitschke, R;Feyereisen, R
最近对茉莉酸（JA）生物合成突变体的研究表明，茉莉酸在花粉成熟和开裂以及对生物攻击的伤害诱导防御中起重要作用。为了更好地了解这种必需的植物激素的生物合成机制，我们分离出一个拟南芥JA生物合成基因CYP 74 A（丙二烯氧化物合酶，AOS）缺陷敲除突变体，使用反向遗传学筛选方法。这种酶在JA生物合成途径中催化氢过氧化物脱水为不稳定的丙二烯氧化物。内源性JA水平，增加100倍，1小时后，在野生型植物受伤，不增加受伤后的aos突变体。此外，该突变体表现出严重的雄性不育，由于在花药和花粉发育的缺陷。雄性不育表型完全获救的外源应用茉莉酸甲酯和互补与组成型表达的AOS基因。RT-PCR分析表明，诱导的营养贮藏蛋白和脂氧合酶基因，以前被证明是可诱导的伤口和茉莉酸盐的应用在野生型的转录本，是不存在的aos突变体。在组成型表达AOS的转基因植物中，伤口诱导的JA水平比野生型植物高50-100%。考虑到JA缺乏的AOS突变体，我们的研究结果表明，AOS是所有生物活性茉莉酸的生物合成的关键。我们的研究结果还表明，AOS的表达是限制在受伤的植物JA水平，但AOS氢过氧化物底物水平，上游酶（脂氧合酶和磷脂酶）控制，确定JA水平在未受伤的植物。
Recent studies on jasmonic acid (JA) biosynthetic mutants have shown that jasmonates play essential roles in pollen maturation and dehiscence and wound-induced defence against biotic attacks. To better understand the biosynthetic mechanisms of this essential plant hormone, we isolated an Arabidopsis knock-out mutant defective in the JA biosynthetic gene CYP74A (allene oxide synthase , AOS ) using reverse genetics screening methods. This enzyme catalyses dehydration of the hydroperoxide to an unstable allene oxide in the JA biosynthetic pathway. Endogenous JA levels, which increase 100-fold 1 h after wounding in wild-type plants, do not increase after wounding in the aos mutant. In addition, the mutant showed severe male sterility due to defects in anther and pollen development. The male-sterile phenotype was completely rescued by exogenous application of methyl jasomonate and by complementation with constitutive expression of the AOS gene. RT-PCR analysis showed that the induction of transcripts for vegetative storage protein and lipoxygenase genes, previously shown to be inducible by wound and jasmonate application in the wild-type, was absent in the aos mutant. In transgenic plants constitutively expressing AOS , wound-induced JA levels were 50-100% higher compared to wild-type plants. Taken together with JA deficiency in the aos mutant, our results show that AOS is critical for the biosynthesis of all biologically active jasmonates. Our results also suggest that AOS expression is limiting JA levels in wounded plants, but that the AOS hydroperoxide substrate levels, controlled by upstream enzymes (lipoxygenase and phospholipase), determine JA levels in unwounded plants.