Symbiotic microorganisms improve nutrient uptake by plants. To initiate mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi, plants perceive Myc factors, including lipochitooligosaccharides (LCOs) and short-chain chitooligosaccharides (CO4/CO5), secreted by AM fungi. However, the molecular mechanism of Myc factor perception remains elusive. In this study, we identified a heteromer of LysM receptor-like kinases consisting of OsMYR1/OsLYK2 and OsCERK1 that mediates the perception of AM fungi in rice. CO4 directly binds to OsMYR1, promoting the dimerization and phosphorylation of this receptor complex. Compared with control plants, Osmyr1 and Oscerk1 mutant rice plants are less sensitive to Myc factors and show decreased AM colonization. We engineered transgenic rice by expressing chimeric receptors that respectively replaced the ectodomains of OsMYR1 and OsCERK1 with those from the homologous Nod factor receptors MtNFP and MtLYK3 of Medicago truncatula. Transgenic plants displayed increased calcium oscillations in response to Nod factors compared with control rice. Our study provides significant mechanistic insights into AM symbiotic signal perception in rice. Expression of chimeric Nod/Myc receptors achieves a potentially important step toward generating cereals that host nitrogen-fixing bacteria.

共生微生物改善植物对养分的吸收。为了启动与丛枝菌根（AM）真菌的共生共生，植物应感知Myc因子，包括AM真菌分泌的脂低聚寡糖（LCO）和短链低聚寡糖（CO4 / CO5）。但是，Myc因子感知的分子机制仍然难以捉摸。在这项研究中，我们确定了由OsMYR1 / OsLYK2和OsCERK1组成的LysM受体样激酶的异源体，其介导水稻中AM真菌的感知。CO4直接与OsMYR1结合，从而促进该受体复合物的二聚化和磷酸化。与对照植物相比，Osmyr1和Oscerk1突变水稻植物对Myc因子较不敏感，并显示出AM定植减少。我们通过表达嵌合受体改造了转基因水稻，嵌合受体分别用run苜蓿的同源Nod因子受体MtNFP和MtLYK3取代了OsMYR1和OsCERK1的胞外域。与对照水稻相比，转基因植物对Nod因子的响应显示出增加的钙振荡。我们的研究为水稻AM共生信号知觉提供了重要的机械见解。嵌合Nod / Myc受体的表达迈出了一个重要的一步，即生产了携带固氮细菌的谷物。