Department of Horticulture, Washington State University, PO Box 646414, Pullman, WA, 99164, USA.
Transgenic Res. 2013 Dec;22(6):1119-31. doi: 10.1007/s11248-013-9715-6. Epub 2013 Jun 2.
Powdery mildew (PM) is one of the major plant pathogens. The conventional method of PM control includes frequent use of sulfur-based fungicides adding to production costs and potential harm to the environment. PM remains a major scourge for Rosaceae crops where breeding approaches mainly resort to gene-for-gene resistance. We have tested an alternate source of PM resistance in Rosaceae. Mildew resistance locus O (MLO) has been well studied in barley due to its role in imparting broad spectrum resistance to PM. We identified PpMlo1 (Prunus persica Mlo) in peach and characterized it further to test if a similar mechanism of resistance is conserved in Rosaceae. Due to its recalcitrance in tissue culture, reverse genetic studies involving PpMloI were not feasible in peach. Therefore, Fragaria x ananassa LF9 line, a taxonomic surrogate, was used for functional analysis of PpMlo1. Agrobacterium-mediated transformation yielded transgenic strawberry plants expressing PpMlo1 in sense and antisense orientation. Antisense expression of PpMlo1 in transgenic strawberry plants conferred resistance to Fragaria-specific powdery mildew, Podosphaera macularis. Phylogenetic analysis of 208 putative Mlo gene copies from 35 plant species suggests a large number of duplications of this gene family prior to the divergence of monocots and eudicots, early in eudicot diversification. Our results indicate that the Mlo-based resistance mechanism is functional in Rosaceae, and that Fragaria can be used as a host to test mechanistic function of genes derived from related tree species. To the best of our knowledge, this work is one of the first attempts at testing the potential of using a Mlo-based resistance strategy to combat powdery mildew in Rosaceae.
白粉病（PM）是主要的植物病原体之一。PM 常规防治方法包括频繁使用硫磺基杀菌剂，这不仅增加了生产成本，还可能对环境造成潜在危害。PM 仍然是蔷薇科作物的主要祸害，而这些作物的育种方法主要依赖于基因对基因的抗性。我们已经在蔷薇科植物中测试了一种替代的 PM 抗性来源。由于大麦中 MLO（花粉外壁缺失）基因在赋予广谱 PM 抗性方面的作用，该基因已得到深入研究。我们在桃中鉴定了 PpMlo1（桃 Mlo），并进一步对其进行了特征描述，以测试在蔷薇科植物中是否存在类似的抗性机制。由于其在组织培养中的抗性，在桃中进行涉及 PpMlo1 的反向遗传学研究是不可行的。因此，使用了草莓的分类替代物 Fragaria x ananassa LF9 系进行 PpMlo1 的功能分析。农杆菌介导的转化产生了在正义和反义方向表达 PpMlo1 的转基因草莓植物。在转基因草莓植物中反义表达 PpMlo1 赋予了对草莓特异性白粉病 Podosphaera macularis 的抗性。对来自 35 种植物的 208 个假定 Mlo 基因拷贝的系统发育分析表明，在单子叶植物和双子叶植物分化之前，该基因家族发生了大量的复制，这发生在双子叶植物多样化的早期。我们的结果表明，基于 Mlo 的抗性机制在蔷薇科植物中是有效的，并且可以将草莓用作测试来自相关树种基因的机制功能的宿主。据我们所知，这项工作是首次尝试利用基于 Mlo 的抗性策略来防治蔷薇科植物白粉病的工作之一。
