外生菌根真菌提高黑松耐盐性作用机制研究

Utilization of saline soil is not only an economic issue, but also an important matter of eco-environment. Mycorrhizas, as symbiotic associations established between the roots of plants and specialized soil fungi, are essential for host plant in enhancing the ability to resist biotic and abiotic stresses, which is beneficial to the survival of the host plants under extreme environmental conditions. Although the resources of the ectomycorrhizal fungi are rich, the investigation is far from enough in saline soil both at home and abroad. In this study: (1) To get saline tolerance fungal strains, the salt tolerence of fungi collected in main coastal forest areas along the Yellow Sea are tested. Besides, to get mycorrhizal seedlings, the inoculation methords are used; (2) To understand how the infection of ectomycorrhizal fungi improve the salt tolerence of Pinus thunbergii, host and rhizosphere microenvironment changes are analyzed; (3) To check the adaptation mechanisms of ectomycorrhizal structure effects on pine host, as well as in forestation, under salt stress , bait seedlings are used in field trials. The results of this study are helpful to enrich ectomycorrhizal fungi resources in saline areas, to understand how ectomycorrhizal fungal species and community structure effects the responses of host to saline stress in coastal forest area, to use mycorrhizal technology in forestation, as well as to assist plant in phytoremediation of saline soils.

合理利用盐渍土壤是集经济与生态于一体的重要科学问题。外生菌根真菌与木本植物根系形成的菌根可以有效提高宿主的耐逆性，有利于宿主植物在极端环境条件下生存。外生菌根真菌资源丰富，但国内外针对盐渍土壤外生菌根菌研究力度不足。基于此本课题：（1）对黄海沿海盐渍地主要林区外生菌根真菌进行采集，纯培养，对获得外生菌根真菌进行耐盐性分析，同时进行菌根化幼苗合成；（2）从宿主、根际微环境角度分析菌根侵染对宿主黑松耐盐性的影响及其机制；（3）采用野外诱捕试验，研究菌根群落结构对宿主定植的影响及对盐胁迫的适应机制。本研究对于丰富我国盐渍土壤外生菌根真菌资源、了解其种群结构及其影响宿主对盐胁迫的适应机制、利用菌根技术提高沿海盐渍土壤的树苗成活率、加快其生态恢复具有重要意义。

菌根真菌的成功侵染可以有效提高宿主植物的耐逆性，深入研究不同宿主及其相关共生外生菌根（ECM）真菌及其群落结构将成为一个重要的研究方向，将为盐碱地林业重建及恢复提供理论基础及技术支持。. 野外调查显示黄海沿海岸带林区ECM群落结构具有典型特征：少数菌种占优势，大部分菌种相对丰度较低。土壤性质（pH、K和Na含量）往往影响ECM真菌的存活、传播以及共生结构的形成。纯培养耐性试验显示盐胁迫会抑制ECM菌丝生长，不同ECM真菌对盐的适应性不同。同为耐盐性真菌的Cenococcum geophilum (Cg)和Pisolithus sp.（P. sp），在盐胁迫下，Cg能将菌丝内的Na含量维持在较低的水平，为拒盐型；而P. sp菌丝内的Na含量会随着处理浓度的增大而升高，为聚盐型。盐胁迫下，Cg和P. sp能维持菌丝内元素平衡，而Laccaria amethystina（La）菌丝内元素严重失衡，K大量流失。P. sp也可能通过置换细胞壁上的Ca缓解Na毒害。. ECM真菌可以通过减少根部Na的吸收来降低最易受到毒害的植物根部的Na/K比值，或是促进K大量从地下往地上部转运，维持甚至降低叶片中Na/K比值，调节植物体细胞内离子平衡，同时，菌根化使得幼苗的光合能力增强，光合产物增多，增加植物体内脯氨酸含量，提高植物的耐盐性。. 采用根室实验考察ECM真菌（Cg、La）促进宿主生长、辅助宿主定植在POPs污染土壤的潜力。菌根真菌的侵染显著提高了幼苗的生长，降低了BDE-209在宿主体内的浓度。同时发现ECM真菌菌丝体对污染土壤中的BDE-209有富集、降解作用，降低了有机污染物向周围作物扩散和淋滤的风险。接种EMF的松树幼苗可以通过稳定、降解污染物的方式来达到有机污染土壤的林业重建与修复的效果，具有一定的应用潜力。.