极旱荒漠灌丛土壤共生真菌物种多样性及其生态响应研究

Desert shrub such as Gymnocarpos przewalskii,Nitraria sphaerocarpa, Reaumuria soongorica, Sympegma regelii, Salsola passerina is the typical zonal vegetation in the arid desert region of northwest China, and is increasingly paid attention for its special regional environment, vegetation distribution characteristics and scientific value. The symbiotic relationships between desert plant and soil fungi served as a starting point of this project. Soil and roots samples were collected for three consecutive years, according to the different season,host plants and sampling plots of shrub inside and outside(Gansu Anxi extra Arid Desert National Nature Reserve). AM and DSE fungi were collected and cultured, and fungal species were classificated and identificated in terms of morphology, micromorphology, histological chemistry, molecular biology and ecological variation and variation of traits analyzing.The community composition and species diversity of AM and DSE fungi, and interaction with host plants and soil environment. Afterward,the succession dynamics of AM and DSE fungi and formation mechanism of mycorrhizal symbiosis with the species differentiation of host plants were clarified, and new symbiotic structure and species information of AM and DSE fungi were excavated.In summary, this project is to reveal the symbiotic mechanism of host plant and soil fungi, and ecological strategy adaptable to the extreme desert environments, and provide evidence for the occurrence and development of the extremely arid desert flora and revegetation in the northwest China.

我国西北极旱荒漠环境特殊的灌丛植被分布和生长特性以及科学价值倍受关注。本项目以植物与土壤真菌共生关系作为切入点，连续三年在甘肃安西极旱荒漠国家级自然保护区分季节、宿主植物、灌丛内外采集土壤和根系样品，分离培养AM和DSE真菌，通过形态学、微形态学、组织化学、分子生物学研究相结合，进行真菌生态变异、性状变异统计和系统分类，比较分析不同宿主植物AM和DSE真菌群落组成、物种多样性及其环境因子的生态功能，探明AM和DSE真菌物种多样性随宿主植物种间分化的变化规律和菌根形成特征；发掘新的共生结构和物种信息，阐明荒漠灌丛与土壤真菌共生机制及其适应极旱环境的生态策略，为揭示我国西北极旱荒漠植物区系发生、发展和植被恢复提供依据。

灌丛是极旱荒漠环境的典型地带性植被类型，在维护生态平衡和生态系统生产力方面发挥着重要作用。本项目首次研究了我国西北极旱荒漠灌丛微生物群落结构和功能多样性，AM和DSE真菌物种多样性及其时空分布规律。共分离鉴定AM真菌13属89种，DSE真菌21属33种，发现自然条件下，部分DSE菌株能够产生休眠孢子。其中DSE真菌Alternaria alternata, Aporospora terricola, Darksidea zeta, Embellisia astragali和Sarocladium implicatum为荒漠生态系统首次报道。极旱荒漠灌丛根际土壤微生物群落结构以细菌为主，其中革兰氏阴性菌>革兰氏阳性菌>放线菌>真菌>AM真菌；主要利用的碳源类型包括碳水化合物，羧酸，多聚物类，胺类，酚酸类和氨基酸类。目标植物均能与AM和DSE真菌形成良好共生体，AM真菌孢子表面纹饰、附属结构等微形态特征和分子特征对于AM真菌物种多样性研究有重要参考价值。AM和DSE真菌物种多样性和生态分布具有明显时空异质性，并与宿主植物和环境因子密切相关。植物内生真菌群落结构具有明显宿主和组织偏好性，根茎组织真菌群落组成在不同宿主间的差异显著大于叶组织。灌丛与真菌共生是其适应极端干旱荒漠环境的重要因素。共生真菌群落结构和生态分布时空异质性能够综合反映荒漠土壤质量变化状况，应作为土壤质量和功能评价的新指标。本项研究成果不仅能够丰富荒漠恢复生态学的基础理论，而且为揭示我国西北极旱荒漠植物区系发生、发展和植被恢复提供材料和依据。