Sainsbury Laboratory, University of Cambridge, 47 Bateman Street, Cambridge, CB2 1LR, UK.
Department of Cell and Developmental Biology, John Innes Centre, Norwich, NR4 7UH, UK.
Nat Commun. 2019 Nov 6;10(1):5047. doi: 10.1038/s41467-019-12999-5.
Plants associate with beneficial arbuscular mycorrhizal fungi facilitating nutrient acquisition. Arbuscular mycorrhizal fungi produce chitooligosaccharides (COs) and lipo-chitooligosaccharides (LCOs), that promote symbiosis signalling with resultant oscillations in nuclear-associated calcium. The activation of symbiosis signalling must be balanced with activation of immunity signalling, which in fungal interactions is promoted by COs resulting from the chitinaceous fungal cell wall. Here we demonstrate that COs ranging from CO4-CO8 can induce symbiosis signalling in Medicago truncatula. CO perception is a function of the receptor-like kinases MtCERK1 and LYR4, that activate both immunity and symbiosis signalling. A combination of LCOs and COs act synergistically to enhance symbiosis signalling and suppress immunity signalling and receptors involved in both CO and LCO perception are necessary for mycorrhizal establishment. We conclude that LCOs, when present in a mix with COs, drive a symbiotic outcome and this mix of signals is essential for arbuscular mycorrhizal establishment.
植物与有益的丛枝菌根真菌共生，从而促进养分的获取。丛枝菌根真菌产生几丁寡糖（COs）和脂几丁寡糖（LCOs），促进共生信号转导，导致核相关钙的振荡。共生信号转导的激活必须与免疫信号转导的激活相平衡，而在真菌相互作用中，免疫信号转导的激活是由源自几丁质真菌细胞壁的 COs 促进的。在这里，我们证明 CO4-CO8 可以诱导蒺藜苜蓿中的共生信号转导。CO 的感知是受体样激酶 MtCERK1 和 LYR4 的功能，它们激活免疫和共生信号转导。LCOs 和 COs 的组合协同作用增强共生信号转导，抑制免疫信号转导，而参与 CO 和 LCO 感知的受体对于菌根的建立是必需的。我们得出结论，LCOs 与 COs 混合存在时，会导致共生结果，这种信号混合物对于丛枝菌根的建立是必不可少的。
