AM真菌与盐碱化草地藜科植物的共生机理研究

Arbuscular mycorrhizal (abbr. AM) fungi are the most in?uential members of the soil microbiota, which form symbiotic relationships with the majority of terrestrial plants. AM fungi can significantly improve the stress resistance to soil salination, drought, infertility, Etc. The plant of Chenopodiaceae is one of most important floras which are used to revegetation in salination areas. Most previous studies suggested that Chenopods can not be colonized by AM fungi. However, several studies found the mycorrhizae structure in the root system of Chenopods, but the associations between AM fungi and Chenopods, and the effects of AM fungi on the development of Chenopods are still less understood. The object of this proposal is to make clear the symbiotic relationship between AM fungi and Chenopods. Firstly, we study the symbiont relationship between AM fungi and Chenopods using the molecular methods real time -PCR, TRFLP and morphological observation. Secondly, the two-compartment root boxes and isotope tracer (32P and 13C)are introduced to study the marketplace of C-P between AM fungi and Chenopods.Thirdly,the effects of AM fungi on the resistance of Chenopods to salt and drought will be studied, and we can elucidate the soil nutrients, water content and salt on the mycorrhizae formation in Chenopods. The results will help to understand the mechanism of symbiont between AM fungi and Chenopds, make clear the effects of AM fungi on the Chenopod's growth, provide theory basis for digging the capacity of AM fungi on the restoration in salinization region, and enrich the theory of the symbiosis mechanism between AM fungi and plant.

AM真菌广泛存在于各类土壤中，可以与绝大多数陆生植物形成菌根共生体，提高宿主植物的抗盐、抗旱、抗养分贫瘠等能力。藜科植物是盐碱化地区植被恢复的重要植物类群，以往研究多认为藜科植物为非菌根植物。近年来有研究发现藜科植物根内存在菌根结构，但是对AM真菌与藜科植物的共生关系及其影响因素、AM真菌对藜科植物生长发育的效应尚不清楚。本研究拟借助 real time -PCR、T-RFLP等分子手段结合形态观测，研究AM真菌对盐碱化草地藜科植物的侵染状况、采用隔网根箱结合32P和13C双标记研究AM 真菌与藜科植物间的C-P交换问题、研究AM真菌对藜科植物抗盐和抗旱能力的影响、并探明土壤水分、盐分对藜科植物与AM真菌共生关系的影响，揭示AM真菌与藜科植物的共生机制及其影响藜科植物生长的机理，为充分挖掘AM真菌在盐碱化草地植被恢复进程中的潜力提供理论依据，丰富AM真菌与植物互作机理的理论研究。

本项目以藜科植物为研究对象，探讨了藜科植物和丛枝菌根真菌（AM真菌）之间的共生关系。开展的主要研究内容：（1）自然状态下不同盐渍生境藜科植物的AM真菌侵染状况，藜科植物根内菌根结构组成；（2）土壤水分、盐分、养分和pH对藜科植物菌根侵染状况的影响；（3）AM真菌对藜科植物耐盐性的影响，包括对藜科植物叶片SOD，POD等抗氧化酶活性的影响；（4）AM真菌对藜科植物养分吸收的影响，包括藜科植物对AM真菌的C分配情况。研究发现：60%左右的藜科植物可以和AM真菌形成菌根结构，藜科植物根内菌根结构以泡囊为主，丛枝很少；藜科植物菌根侵染状况受土壤水分、盐分和磷养分有效性影响显著和土壤pH关系不大，AM真菌可以通过提高藜科植物体内SOD和POD活性，降低H2O2和MDA含量提高藜科植物的耐盐性；AM真菌能够显著促进藜科植物对磷的吸收，增加地上生物量和种子数量，AM真菌可以将藜科植物光合固定的碳通过菌丝转移分配到土壤。研究结果为理解藜科植物和AM真菌共生关系，以及未来应用AM真菌进行盐碱地植被恢复提供了理论依据。