番茄LysM类受体激酶LYK4调控菌根共生并参与植物防御机制解析

菌根共生能够提高植物对营养元素的吸收、增加植物抗逆性等功能，但其如何与植物形成共生关系的分子机制我们知之甚少。在本研究中，我们在番茄中鉴定了一个与菌根共生相关的基因SlLYK4。蛋白亲和能力测定结果表明，番茄SlLYK4是菌根因子LCO的结合蛋白；沉默SlLYK4基因的表达并接种真菌后，番茄菌根定植量显著提高；SlLYK4-RNAi转基因植株对致病青枯菌的易感性显著增加；在flg22诱导下，突变体根系的ROS代谢和胼胝质沉积明显低于野生型，导致突变体幼苗的生长抑制率降低。上述研究初步揭示了SlLYK4调控番茄菌根共生并参与植物防御。.为深入研究SlLYK4的生物学功能，我们拟利用生物化学与分子生物学手段，结合显微学技术，将进一步探索SlLYK4在菌根共生和植物防御中的调控机制。该结果不仅可以完善LysM类受体激酶在植物细胞内的调控机制，而且为菌根技术在蔬菜产业中的应用提供理论依据。

Plants can benefit a lot from arbuscular mycorrhizal symbiosis such as improving the efficiency of nutrient elements acquisition, increasing plant stress resistance, etc. But, the molecular mechanisms of how mycorrhizal fungi symbiosis with plants is seldom reported. In Solanum lycopersicum, we identified a mycorrhizal symbiotic-related gene SlLYK4 which belongs to the lysin motif receptor-like kinases phylogenetic group. The results of myc-LCO bind assay showed that SlLYK4 and its orthologous in various plant species are LCO binding proteins except AtLYK4 in Arabidopsis thaliana, a species unable to be colonized by arbuscular mycorrhizal fungi. SlLYK4-silenced plants showed an increase level of colonization by the AM fungal strain Rhizophagus irregularis. Moreover, we showed that the SlLYK4 plays a role in regulation of plant defence. In SlLYK4-silenced plants, responses to the bacterial flagellin epitope flg22 such as ROS production and callose deposition were reduced in comparison to controls, and these finally affect the plant growth. SlLYK4-silenced plants showed an increase level of susceptibility by the pathogenic strain Ralstonia solanacearum. Altogether, these results suggest that SlLYK4 regulates the mechanisms of mycorrhizal symbiosis and plant defence..In this research project, the biochemical and molecular biological techniques combining with the microscopic analysis will be applied for further study the biological roles of SlLYK4 in both mycorrhizal symbiosis and plant defence mechanisms. The results and conclusions will reveal the molecular mechanisms of lysin motif receptor-like kinase regulation pathway in plant cell, and also will be the theoretical basis of ecological agriculture.