豆科植物共生结瘤的分子基础和调控研究进展

Review of research advancements on the molecular basis and regulation of symbiotic nodulation of legumes

豆科植物与根瘤菌共生互作的结果导致了一个新的植物器官——根瘤的形成,根瘤菌生活在根瘤中,它们具有将氮气转化为能被植物同化的氨的能力。该文阐述了根瘤的形成过程和类型,并主要以模式豆科植物蒺藜苜蓿(Medicago truncatula)和日本百脉根(Lotus japonicus)为例,对近年来共生结瘤过程中宿主植物对根瘤菌结瘤因子的识别和信号传递、侵入线形成和固氮的分子基础,以及宿主植物对根瘤形成的自主调控机制、环境中氮素营养对结瘤的影响研究进行了综述,指出当前豆科植物与根瘤菌共生互作研究存在的问题,并对今后的研究方向作了分析与展望。

The symbiosis between leguminous plants and rhizobia leads to the formation of a novel root organ,the nodule.In mature nodules,rhizobia provide the host plant with ammonium,which is produced through bacterial nitrogen fixation.The symbiotic interactions involve the perception of bacterial signaling factors called Nod factors （NFs） by plant host,the NF signaling pathway,the formation of infection threads and the development of nodule in the cortex.Although this nodule formation is beneficial for host plants to secure a nitrogen resource,overproduction of nodules could deleteriously affect plant growth.Legume plants avoid this by utilizing a negative feedback regulation known as autoregulation of nodulation （AON）,in which earlier formed nodules suppress further nodulation through shoot-root communication.We summarize nodule formation and types and highlight recent studies on the molecular basis underlying NF signaling cascade,AON and effects of environmental nitrogen conditions on nodulation.We also discuss current research problems and reflect on the future of this field.