中科院上海植生生态所揭示菌根共生转录调控分子机制

中科院上海生命科学研究院植物生理生态研究所王二涛组研究揭示植物-菌根共生的转录调控机理和植物激素赤霉素通过DELLA蛋白调节菌根共生的分子机制。文章发表在12月17日《Cell Research》期刊上。



菌根是指植物与土壤中的菌根真菌形成的共生体，分布广泛，超过80%的陆生植物都能够与菌根真菌形成共生体。目前的研究表明，植物-菌根真菌共生是植物由水生向陆生植物进化所必须的，植物-菌根共生的建立在自然界有巨大的竞争优势。在植物-菌根共生中，真菌一方面从植物获得碳源等有机物作为自己的营养，另一方面能够帮助植物高效吸收土壤中的磷、氮等营养元素，显著促进植物的生长。研究植物-菌根共生可能为降低农作物对磷肥和氮肥的利用提供理论基础。

研究人员发现，GA处理植物导致菌根共生能力下降，且呈现出浓度依赖的表型，而与共生相关的下游基因的表达也受到明显的抑制。而植物GA信号通路关键基因DELLA突变体不能与菌根共生，预示着DELLA可能是GA调节植物生长和菌根共生的关键基因。研究人员通过酵母双杂交筛选等试验，获得DELLA的互作的GRAS类型的转录因子DIP1，并且DIP1突变导致植物菌根共生能力的下降。进一步的研究表明，DIP1能够与调控菌根共生的转录因子RAM1直接相互作用，从而调节植物中参与菌根共生下游基因的表达。该研究第一次清晰地揭示出植物-菌根共生过程中的转录因子复合物DELLA-DIP1-RAM1，为我们理解菌根共生如何受环境调控提供了理论基础。

该研究得到了中国科学院战略性先导科技专项的资助。

文章摘要：

A DELLA protein complex controls the arbuscular mycorrhizal symbiosis in plants

Nan Yu, Dexian Luo, Xiaowei Zhang, Junzhong Liu, Wanxiao Wang, Yue Jin, Wentao Dong, Jiyun Liu, Huan Liu, Weibing Yang, Longjun Zeng, Qun Li, Zuhua He, Giles E D Oldroyd and Ertao Wang

lants establish beneficial symbiotic associations with arbuscular mycorrhizal fungi, which colonize the root cortex, building specialized structures called arbuscules that facilitate nutrient exchange. The association occurs following plant recognition of lipochitooligosaccharides (LCOs) from mycorrhizal fungi, which activates the symbiosis signaling pathway prior to mycorrhizal colonization. Here we show that SLR1/DELLA, a repressor of gibberellic acid (GA) signaling, and its interacting partner protein are required for the mycorrhizal symbiosis. GA treatment inhibits mycorrhizal colonization and leads to the degradation of DELLAs. Consistently, rice lines mutated in DELLA are unable to be colonized by mycorrhizal fungi. DELLAs are members of the GRAS family of transcription factors. We further show that rice DELLA interacts with a second GRAS protein, DIP1 (DELLA Interacting Protein 1). DIP1 is also required for mycorrhizal colonization and in turn interacts with a previously characterized mycorrhizal GRAS protein, RAM1, that has been shown to directly regulate mycorrhizal-associated gene expression. We conclude that a complex of GRAS proteins, including DELLAs, is necessary for regulation of mycorrhizal-associated gene expression and thus colonization.

;