Plant genes required for arbuscular mycorrhiza symbiosis

丛枝菌根（AM）是植物根系与球囊霉门真菌共生获得磷的重要途径，具有重要的生态意义和可持续农业的潜力。我们想解开控制这种共生关系的发展和调节的分子机制。为此，我们已经开始了一个遗传筛选AM缺陷的个人内的乙基甲烷磺酸盐（EMS）诱变人口的模式豆科植物百脉根。这种方法导致了21个突变体的集合，这些突变体在AM发育的各个阶段表现出缺陷，同时保持形成根瘤的能力。这些突变体提供了一个有价值的工具，剖析植物的共生的贡献。我们提出了一个详细的表征基因参与AM在表型和分子水平。为此，我们将通过显微镜、转录谱和AM性能分析来描述突变体表型。我们将通过定义粗略的图谱位置和互补群来继续突变体的遗传特征。至少有两个突变体显示在早期发育阶段的缺陷，和12个突变体受损的丛枝发育过程中。我们建议通过图位克隆来鉴定至少两个缺陷基因。随后，我们将功能性地表征所鉴定的基因及其基因产物。到目前为止，还没有一个特定的基因所需的AM共生已确定通过正向遗传方法。因此，这项研究的结果将为AM的遗传基础提供新的和重要的见解。

The phosphate acquiring arbuscular mycorrhiza (AM) symbiosis between plant roots and Glomeromycota fungi is of prime ecological importance and bears potential for sustainable agriculture. We would like to unravel the molecular mechanisms that control development and regulation in this symbiosis. To this end, we have initiated a genetic screen for AM-defective individuals within an ethylmethane sulfonate (EMS)-mutagenized population of the model legume Lotus japonicus. This approach has resulted in a collection of 21 mutants that exhibit defects at various stages of AM development while maintaining the capacity to form root nodules. These mutants provide a valuable tool to dissect the plant's contribution to symbiosis. We propose a detailed characterization of the genes involved in AM both at the phenotypic and molecular level. For this we will describe the mutant phenotype by microscopy, transcriptional profiling and analysis of AM performance. We will continue the genetic characterization of the mutants by defining rough map positions and complementation groups. At least two of the mutants display defects at early developmental stages, and twelve mutants are impaired during arbuscule development. We propose to identify at least two of the defective genes by map-based cloning. Subsequently, we will functionally characterize the identified genes and their gene products. So far, not a single gene specifically required for AM symbiosis has been identified through forward genetic approaches. The results from this study will therefore provide novel and important insights into the genetic basis of AM.