Maize 9-lipoxygenase ZmLOX3 controls development, root-specific expression of defense genes, and resistance to root-knot nematodes
Maize 9-lipoxygenase ZmLOX3 controls development, root-specific expression of defense genes, and resistance to root-knot nematodes
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DOI：
10.1094/mpmi-21-1-0098
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发表时间：
2008-01-01
影响因子：
3.5
通讯作者：
Kolomiets, Michael
中科院分区：
文献类型：
--
作者：
Gao, Xiquan;Starr, James;Kolomiets, Michael
根结线虫(RKN)是玉米的一种严重害虫。尽管脂氧合酶(LOX)途径及其氧合脂质产物参与了植物与线虫的相互作用，但在本报告之前，还没有确凿的遗传证据证明任何植物LOX基因在这种相互作用中起作用。结果表明，玉米9-LOX基因ZmLOX3在接种南方根结线虫RKN后稳定表达，并在接种后7d达到高峰。MU插入的LOX3-4突变体对RKN的诱惑力增强，幼虫和卵的数量增加。一组茉莉酸(JA)和乙烯(ET)反应基因和生物合成基因以及水杨酸(SA)依赖基因在LOX3-4突变体的根中特异表达。与此一致的是，在LOX3-4突变体的根中，JA、SA和ET的水平升高，而在叶片中则没有。与野生型不同，在LOX3-4突变根中，苯丙氨酸解氨酶(PAL)基因不是RKN诱导的，这表明PAL介导的代谢在线虫抗性中发挥了作用。除了根系防御状态的这些变化外，与野生型相比，LOX3-4基因敲除突变体还表现出早熟衰老、根长和株高降低的现象，表明ZmLOX3是植物正常发育所必需的。综上所述，我们的数据表明，ZmLOX3介导的途径可能是所有三个主要防御信号途径的根特异抑制因子，将植物能量输送到生长过程中，但这是正常水平对线虫的抗性所必需的。
Root-knot nematodes (RKN) are severe pests of maize. Although lipoxygenase (LOX) pathways and their oxylipin products have been implicated in plant-nematode interactions, prior to this report there was no conclusive genetic evidence for the function of any plant LOX gene in such interactions. We showed that expression of a maize 9-LOX gene, ZmLOX3, increased steadily and peaked at 7 days after inoculation with Meloidogyne incognita RKN. Mu-insertional lox3-4 mutants displayed increased attractiveness to RKN and an increased number of juveniles and eggs. A set of jasmonic acid (JA)- and ethylene (ET)-responsive and biosynthetic genes as well as salicylic acid (SA)-dependent genes were overexpressed specifically in the roots of lox3-4 mutants. Consistent with this, levels of JA, SA, and ET were elevated in lox3-4 mutant roots, but not in leaves. Unlike wild types, in lox3-4 mutant roots, a phenylalanine ammonia lyase (PAL) gene was not RKN-inducible, suggesting a role for PAL-mediated metabolism in nematode resistance. In addition to these alterations in the defense status of roots, lox3-4 knockout mutants displayed precocious senescence and reduced root length and plant height compared with the wild type, suggesting that ZmLOX3 is required for normal plant development. Taken together, our data indicate that the ZmLOX3-mediated pathway may act as a root-specific suppressor of all three major defense signaling pathways to channel plant energy into growth processes, but is required for normal levels of resistance against nematodes.