Plant genes required for arbuscular mycorrhiza symbiosis

植物根系与丛枝菌属真菌之间的磷酸盐共生具有重要的生态意义，具有可持续农业的潜力。我们想要解开在这种共生中控制发育和调节的分子机制。为此，我们启动了对模式豆科植物莲花的乙基甲烷磺酸盐(EMS)诱变种群中AM缺陷个体的遗传筛选。这种方法已经导致了21个突变体的集合，这些突变体在AM发育的不同阶段表现出缺陷，同时保持形成根瘤的能力。这些突变体为剖析植物对共生的贡献提供了宝贵的工具。我们从表型和分子水平对AM中涉及的基因进行了详细的描述。为此，我们将通过显微镜、转录图谱和AM性能分析来描述突变表型。我们将通过定义粗略的图谱位置和互补组来继续突变体的遗传特征。至少有两个突变体在早期发育阶段表现出缺陷，12个突变体在丛枝发育过程中受损。我们建议通过基于图谱的克隆来鉴定至少两个缺陷基因。随后，我们将对已鉴定的基因及其基因产物进行功能鉴定。到目前为止，还没有通过正向遗传方法鉴定出AM共生所需的单个基因。因此，本研究的结果将为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.