Colonization And Spore Densities Of AMF In Mangroves Located In Different Regions Of China

So far, the presence of arbuscular mycorrhizal fungi (AMF) in mangrove habitatswere still rarely investigated, and most available reports on AMF in mangroveecosystems are focused on the investigations of AMF colonization intensity andspores density within one or two particular mangrove habitat. Therefore, ourknowledge on the presence and community structures of AMF in mangroveecosystems are still very limited. To the best of our knowledge, there’s no report onhow the AMF colonization is related to the latitudinal gradient under different areas.In this study, we investigated the AMF colonization rate and spores density in sixmangrove areas in four coastal provinces (Zhejiang, Fujian, Guangdong and Hainan)of mainland China. The physicochemical properties of rhizosphere soil were detectedto explore the potential soil factors which might affect the symbiotic of AMF andmangroves and regional characteristics of AMF infection were explored. The mainresults were as followed.1) AMF was presented in all the six surveyed mangrove areas, and the proportionof infected mangrove species was high. The AMF infection ratio was100%in XimenIsland of Zhejiang, Zhangjiang Estuary of Fujian and Su’ai Bay of Guangdong,90.9%in Qi’ao Island of Guangdong,81.8%in Gaoqiao of Guangdong, and75.0%inDongzhaigang of Hainan which was the lowest.2) AMF species were largely different from each other among the investigatedmangrove ecosystems. A totall of13species of AMF spores were identified,including10species belonging to Glomus,2species belonging to Paraglomus and1species belonging to Acaulospora. Other four AMF spore types could not beidentified based on their morphological characteristics which were observed. Among the investigated areas, the species diversity of AMF spores was increased at thebeginning, and then decreased with increasing latitude. The number of spore speciesfound in Ximen Island of Zhejiang, Zhangjiang Estuary of Fujian, Su’ai Bay ofGuangdong, Qi’ao Island of Guangdong, Gaoqiao of Guangdong and Dongzhaigangof Hainan was5,16,14,13,12and10respectively.3) The AMF spores densities in rhizosphere soil were largely different from eachother among investigated mangrove areas. The average spores density was27.2per25g (dry weight) soil in Ximen Island of Zhejiang,507.5per25g soil in ZhangjiangEstuary of Fujian,730.1per25g soil in Su’ai Bay of Guangdong,566.4per25g soilin Qi’ao Island of Guangdong,305.3per25g soil in Gaoqiao of Guangdong and256.4per25g soil in Dongzhaigang of Hainan. With increasing latitude, the AMFspores density was first increased and then decreased.4) Soil factors had different impacts on AMF colonization and spores density indifferent mangrove areas, and the symbiotic between AMF and host plants wasaffected by different factors. Organic matter was the main affecting soil factors inXimen Island of Zhejiang, Zhangjiang Estuary of Fujian and Su’ai Bay of Guangdong.Organic matter, pH, total phosphorus and available nitrogen play a major role in Qi’aoIsland of Guangdong, while organic matter, electrical conductivity, and availablephosphorus in Gaoqiao of Guangdong and organic matter, electrical conductivity andavailable nitrogen in Dongzhaigang of Hainan. The organic matter content seems tobe the most important soil factor affecting the AM symbiosis in the mangroveecosystem, since it showed significant impact on AMF colonization in all theinvestigated mangrove areas.5) No obvious trends of AMF colonization rate is found with increasing latitude.Except that Acanthus ilicifolius and Aegiceras corniculatum had a similar trend withincreasing latitude. The AMF colonization intensities were first increased and thendecreased with increasing latitude. The highest AMF colonization levels for these twospecies were both detected at Zhangjiang Estuary of Fujian. The AMF colonizationrates of Excoecaria agallocha and Clerodendrum inerme were higher than the otherspecies in all the surveyed regions, while the AMF colonization rates of Kandliacandel and Bruguiera gymnorrhisa were very low.