滨海湿地AMF多样性及其对红树耐受/适应逆境机理的影响

Based on the previous progresses we have made, our research team will further combine field studies with laboratory simulation, using morphological method to identify the arbuscular mycorrhizal fungi (AMF) colonization rate and structure in mangrove roots of typical mangrove ecosystem, and using SSU-ITS-LSU fragment (provided by Sanger sequencing) and shorter fragments (such as the c. 400- or 800-bp reads provided by 454-sequencing) as the molecular markers, as well as the high-throughput sequencing technology to investigate the AMF diversity in mangrove rhizosphere under different living conditions, thus to explore the AMF biodiversity resources in mangrove ecosystems under different spatiotemporal scales. Through screening, indentification and propagation of the AMF strains, combined with histochemistry method and DNA microarray technology, the effect of AMF on the absorption of biogenic elements as well as the tolerance mechanisms of mangrove to heavy metal and salt stress will be studied. After comprehensive comparison, the dominant AMF species which promote the absorption capacity of nitrogen and phosphorus elements and the tolerance ability to heavy metal and salt stress in mangrove will be identified. The efficient method and technology to prepare and preserve the dominant AMF species will be explored. Our results will develop and perfect the theory of ecological research especially the mangrove rhizosphere ecology research, innovate the screening technology of wetland AMF species, enrich Chinese AMF germplasm resources bank, and provide theoretical basis and technical support to the application of AMF agent in large scale as well as the conservation and recovery of mangrove ecosystem.

在已经取得较好研究进展的基础上，结合野外研究与室内模拟，利用形态学方法研究红树林生态系统中红树根系AMF的侵染率和侵染结构；采用SSU-IST-LSU rDNA长片段序列与400/800bp的短片段rDNA序列相结合的分子标记方法与高通量测序技术研究不同生境中红树根际系统的AMF菌种多样性；系统地开展不同时空条件下红树林生态系统中的AMF生物多样性资源研究。通过筛选、鉴定与扩繁并结合组织化学手段与DNA微阵列技术，研究AMF对红树的生源要素吸收以及对重金属、盐耐受和适应机理的影响。综合比对鉴定出红树对N、P吸收能力高、对盐及重金属耐受与适应能力强的优势AMF菌种；开发高效制备与保存优势AMF菌剂的方法与技术。丰富和完善生态学尤其是红树林根际生态学研究理论；创新湿地AMF菌剂筛选的技术手段，丰富我国AMF种质资源库，为AMF菌剂推广应用以及为红树林生态系统保育恢复提供科学的理论依据和技术支撑

丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）与大多数红树植物形成共生关系，对于湿地植物的生长和氮、磷等营养状况都有举足轻重的作用。本项目结合形态学和分子生物学研究方法，发现不同树龄秋茄根际土壤中的孢子数和孢子形态均表现出差异，成熟秋茄的孢子数量更多，形态上亦趋于“成熟化”，且根际AMF群落也呈现出差异性。同时，项目从红树林湿地中分离、筛选和鉴定出多株高效的优势AMF和解磷微生物（phosphate-solubilizing microorganism, PSM）菌种，并在室内模拟试验中证实，多株菌株对红树植物的生长、营养吸收、光合作用和解剖结构等都具有显著的积极作用。这有利于丰富和完善我国湿地功能菌的种质资源库，为红树林生态系统的恢复和造林提供技术支撑。与此同时，AM真菌也产生一种耐热糖蛋白，即球囊霉素土壤相关蛋白（glomalin-related soil protein，GRSP），研究结果揭示淹水和盐度是AM真菌生存的主要限制因子，且GRSP的库尺寸和功能极大影响红树林碳库。GRSP在潮间带和近海沉积物中也可以示踪陆源碳的传输和积累，其丰富性可以作为陆-海连接的指示剂。