van Damme Mireille, Huibers Robin P, Elberse Joyce, Van den Ackerveken Guido
Plant-Microbe Interactions, Department of Biology, Science Faculty, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Plant J. 2008 Jun;54(5):785-93. doi: 10.1111/j.1365-313X.2008.03427.x. Epub 2008 Jan 31.
The Arabidopsis mutant downy mildew resistant 6 (dmr6) carries a recessive mutation that results in the loss of susceptibility to Hyaloperonospora parasitica. Here we describe the map-based cloning of DMR6 (At5g24530), which was found to encode a 2-oxoglutarate (2OG)-Fe(II) oxygenase of unknown function. DMR6 transcription is locally induced during infections with both compatible and incompatible H. parasitica isolates. High DMR6 transcript levels were also observed in constitutive defense mutants and after treatment with salicylic acid analog BTH, suggesting that DMR6 has a role during plant defense. Expression analysis of dmr6 mutants, using DNA microarrays and quantitative PCR, showed the enhanced expression of a subset of defense-associated genes, including DMR6 itself, suggesting dmr6-mediated resistance results from the activation of plant defense responses. Alternatively, resistance could be caused by the accumulation of a toxic DMR6 substrate, or by the absence of a DMR6 metabolic product that is required for H. parasitica infection.
拟南芥霜霉病抗性突变体6（dmr6）携带一个隐性突变，该突变导致对寄生霜霉（Hyaloperonospora parasitica）失去易感性。在此，我们描述了基于图谱克隆的DMR6（At5g24530），发现它编码一种功能未知的2-氧代戊二酸（2OG）-铁（II）加氧酶。在与寄生霜霉的亲和性和非亲和性分离株感染期间，DMR6转录在局部被诱导。在组成型防御突变体中以及用水杨酸类似物BTH处理后，也观察到了高DMR6转录水平，这表明DMR6在植物防御过程中发挥作用。使用DNA微阵列和定量PCR对dmr6突变体进行表达分析，结果显示包括DMR6自身在内的一部分防御相关基因的表达增强，这表明dmr6介导的抗性是由植物防御反应的激活所致。或者，抗性可能是由有毒的DMR6底物积累引起的，也可能是由于寄生霜霉感染所需的DMR6代谢产物缺失所致。
