丛枝菌根真菌对玉米干旱胁迫的响应机制研究

Maize is one of the most important crops in China. Water availability, as a crucial factor in maize product, is significantly affected by drought stress. Therefore, understanding the mechanism of maize drought resistance is pivotal to improve maize production significantly. Arbuscular mycorrhizal (AM) fungi form symbiotic associations with plant roots. AM fungi play a key role in enhancing plant mineral nutrition and water acquisition, improving plant growth and resistant capacity to environmental stresses. However, little is known about the response and function of AM fungi to the drought stress of maize. Therefore, this project will investigate the response and potential function of AM fungi to maize drought stress conducted in glasshouse and crop field. This study will understand the changes of AM fungal biomass in soil and AM structure in roots under drought stress in field based on morphology analysis. Furthermore, the response of active AM fungal diversity and community composition in soil and roots to drought stress will be investigated using meta-transcriptomics. In addition, the potential function of AM fungi in improving drought assistance of maize will be analyzed by mRNA profile. The study will understand the mechanism of AM fungi in improving drought resistance of maize, and promote crop production and agroecosystem sustainability significantly.

玉米是我国重要的粮食作物，而水分是玉米生产的重要限制因子，干旱造成玉米减产、甚至绝产。因此，开展玉米抗旱机理研究，寻找应对策略，提高玉米产量具有重要理论和实际意义。丛枝菌根(AM)真菌与植物形成互惠共生体，可帮助植物吸收土壤中的矿物质营养和水分，促进植物生长及提高抗干旱等不良环境因子胁迫的能力。然而，AM真菌对玉米干旱胁迫的响应及其调节作用尚不清楚。因此，本项目拟结合室内和田间的水分控制实验，通过对土壤中AM真菌的孢子密度和菌丝长度以及根系侵染结构分析，揭示AM真菌的生物量和侵染率对干旱胁迫的响应机制；利用宏转录组高通量测序技术检测土壤和根系内AM真菌的多样性，阐明活性AM真菌的群落结构对干旱胁迫的响应与适应机制；通过mRNA转录谱分析，探讨AM真菌调节玉米抗干旱胁迫的潜在功能。本项目从AM真菌的角度揭示玉米对干旱胁迫的调节机理，为提高玉米产量以及维持农田生态系统的可持续发展提供科学依据。

丛枝菌根（Arbuscular mycorrhiza，AM）真菌作为一类重要的功能性微生物，对植物的水分和营养吸收起关键作用。因此，阐明AM真菌对水肥的响应机制，对利用生物手段提高作物水肥利用效率，维持农田生态系统的可持续发展具有重要的理论和实际意义。本研究以中国科学院阜康荒漠生态站大田玉米为材料，通过水肥控制实验，利用形态学和高通量测序技术，开展AM真菌侵染结构及群落组成对干旱及氮磷添加的响应研究。结果表明：玉米生长阶段对AM真菌孢子密度、菌丝长度和侵染率具有显著影响，抽雄期和收获期孢子密度均显著高于拔节期。水分条件显著影响AM真菌的菌丝长度和侵染率，而对孢子密度无显著影响。与不施氮相比，施氮降低了AM真菌孢子密度和侵染率，对菌丝长度无显著影响。而施磷对AM真菌孢子密度、菌丝长度和侵染率均无显著影响。通过对玉米不同生长阶段及水肥条件下AM真菌高通量测序数据分析，共得到66个AM真菌可操作分类单元（OTU），球囊霉科（Glomeraceae）为优势类群。土壤AM真菌多样性高于根系。土壤AM真菌多样性在正常水分条件下随生长阶段显著降低，而在干旱条件下随生长阶段显著升高；根系AM真菌多样性在正常水分和干旱条件下均随生长阶段而升高，抽雄期和收获期显著高于拔节期。施氮和施磷对土壤和根系AM真菌多样性均无显著影响。玉米根系和土壤AM真菌群落结构对施肥和水分的响应不同，且显著受玉米生育期影响。干旱影响根系AM真菌群落，而不影响土壤AM真菌。施氮影响土壤AM真菌群落组成而不影响根系AM真菌。施磷则对土壤和根系AM真菌群落组成均无显著影响。研究结果对从共生真菌角度提高作物水肥利用效率，维持农田生态系统的可持续发展提供理论支撑。