Ascorbate oxidation activates systemic defence against root-knot nematode Meloidogyne graminicola in rice
Ascorbate oxidation activates systemic defence against root-knot nematode Meloidogyne graminicola in rice
复制标题
DOI：
10.1093/jxb/eraa171
复制
发表时间：
2020-07-06
影响因子：
6.9
通讯作者：
Kyndt, Tina
中科院分区：
文献类型：
--
作者：
Singh, Richard Raj;Verstraeten, Bruno;Kyndt, Tina
抗坏血酸(AA)是植物地上部组织中产生的主要抗氧化缓冲物质。已有的研究表明，水稻根结线虫(Meloidogyne Graminicola)侵染水稻植株后，AA循环基因的表达存在差异，但其功能作用尚不清楚。我们的结果证实了线虫诱导的根瘤中脱氢抗坏血酸(DHA)水平的增加，而AA突变体明显更容易受到线虫的感染。外部应用抗坏血酸氧化酶(AO)，DHA，或还原的AA，揭示了抗坏血酸氧化对水稻防御的系统效应，而不是RKN，与线虫侵染时H_2O_2的初始积累有关。为了证实和进一步研究这些系统效应，对植物根进行了转录组分析，揭示了根中乙烯(ET)反应和茉莉酸(JA)生物合成途径的激活，这一点得到了激素测量的证实。通过甲基茉莉酸或乙烯利处理激活这些途径可以补充水稻维生素C(Vtc1)突变体的敏感性表型。对茉莉酸信号转导(JAR1)突变体或使用化学JA/ET抑制剂的实验证实，抗坏血酸氧化的影响取决于JA和ET途径。总之，我们的数据揭示了一种新的途径，在该途径中，抗坏血酸氧化诱导对RKNS的系统性防御。
Ascorbic acid (AA) is the major antioxidant buffer produced in the shoot tissue of plants. Previous studies on root-knot nematode (RKN; Meloidogyne graminicola)-infected rice (Oryza sativa) plants showed differential expression of AA-recycling genes, although their functional role was unknown. Our results confirmed increased dehydroascorbate (DHA) levels in nematode-induced root galls, while AA mutants were significantly more susceptible to nematode infection. External applications of ascorbate oxidase (AO), DHA, or reduced AA, revealed systemic effects of ascorbate oxidation on rice defence versus RKN, associated with a primed accumulation of H2O2 upon nematode infection. To confirm and further investigate these systemic effects, a transcriptome analysis was done on roots of foliar AO-treated plants, revealing activation of the ethylene (ET) response and jasmonic acid (JA) biosynthesis pathways in roots, which was confirmed by hormone measurements. Activation of these pathways by methyl-JA, or ethephon treatment can complement the susceptibility phenotype of the rice Vitamin C (vtc1) mutant. Experiments on the jasmonate signalling (jar1) mutant or using chemical JA/ET inhibitors confirm that the effects of ascorbate oxidation are dependent on both the JA and ET pathways. Collectively, our data reveal a novel pathway in which ascorbate oxidation induces systemic defence against RKNs.