Spatial regulation of rice D14L for pre-symbiotic perception of beneficial fungi

地球上高等生命进化的一个关键事件是植物从水到陆地的过渡。为了探索陆地环境，植物必须制定策略，利用最初的原始根系前体获取土壤养分。从那时起，植物就与提供营养的有益真菌共生。今天，丛枝菌根(AM)共生是地球上最常见的有益植物-真菌相互作用，有助于植物适应性、植物生物多样性和全球营养循环。然而，我们才刚刚开始揭开根际相互认可的分子过程的面纱。AM真菌对植物根部的定植需要在真菌附着到根表面之前，可扩散分子的相互交换。AM真菌分泌的甲壳素相关化合物可触发植物分子和发育反应。受体激酶蛋白检测细胞外空间中的这些真菌分子，并启动细胞重新编程，导致根系发育的变化。突变分析表明，这些受体激酶确实是AM共生体发育所必需的，但似乎不是必需的。因此，植物如何感知这些普遍存在的有益真菌仍然是一个悬而未决的问题。我的团队发现，细胞内的一种名为Dwarf 14 like(D14L)的细胞内α/β水解酶类型蛋白对水稻对真菌的感知至关重要。在我们最近的《科学》杂志上，我们报道了我们的发现，从水稻基因组中删除了这个基因，导致植物无法感知真菌。有趣的是，这种蛋白质在检测烟雾成分卡里金和调节对光的发育反应方面还有额外的作用。它在进化上是保守的，因此可能在早期陆地植物中具有类似的功能。根对真菌的识别和随后建立的初级接触涉及不同的根组织和细胞类型。因此，信号事件在空间和时间上的精确协调对于AM共生的成功发展至关重要。根据这一建议，我们希望确定蛋白质在根组织中(相对于接近的真菌)需要存在的位置，并通过放大到亚细胞水平，确定蛋白质在启动信号转导中的什么功能以及信号的相应分子翻译。鉴于D14L在对环境刺激的各种反应中的核心作用，阐明参与信号传递的组织/细胞类型对于理解这种普通的和古老的植物共生的协调和特异性至关重要。

A key event in the evolution of higher life on earth is the transition of plant life from water to land. To explore the terrestrial environment plants had to develop strategies for the acquisition of soil nutrients with initially primitive root precursors. Ever since, plants have lived in symbioses with nutrient-delivering beneficial fungi. Today, the arbuscular mycorrhizal (AM) symbiosis is the most commonly occurring beneficial plant-fungal interaction on earth, contributing to plant fitness, plant biodiversity and global nutrient cycles. Yet, we are only beginning to unveil the molecular processes leading to mutual recognition in the rhizosphere. Colonization of plant roots by AM fungi requires the reciprocal exchange of diffusible molecules before fungal attachment to the root surface occurs. Chitin-related compounds secreted by AM fungi trigger plant molecular and developmental responses. Receptor kinase proteins detect these fungal molecules in the extracellular space and initiate a cellular reprogramming leading to a change in root system development. Mutational analyses showed that these receptor kinases are indeed required for development of AM symbioses but appear not to be essential. How plants perceive these prevalent beneficial fungi has therefore still been an unanswered question.My group has found that an intracellular alpha/beta hydrolase type protein, called DWARF 14 LIKE (D14L) is crucial for fungal perception by rice. In our recent Science publication we report our finding that the deletion of this gene from the rice genome rendered the plant unable to sense the fungus. Interestingly, the protein has additional roles in detecting the smoke constituent karrikin and in mediating developmental responses to light. It is evolutionarily conserved and may have therefore served similar functions in early terrestrial plants. The recognition of the fungus by the root and the subsequent establishment of primary contact involves distinct root tissue and cell types. The precise coordination of signaling events in space and time is thus essential for the successful development of AM symbioses. With this proposal we wish to determine where in the root tissue (relative to the approaching fungus) the protein needs to be present, and by magnifying onto the subcellular level, where within the cell the protein functions in initiating signal transduction and what are the respective 'molecular translations' of signalling.Given the central role of D14L in a variety of responses to environmental stimuli elucidating the tissue/cell type contributing to the signaling is vital for understanding coordination and specificity of this general and ancient plant symbiosis.