The Species Diversity Of Arbuscular Mycorrhiza Fungi And Dark Septate Endophytes In Roots Of Baiyangdian Wetland Plants And Screening Of Heavy Metal Resistance DSE Strains

Baiyangdian wetland is located in the central part of Hebei Province,at the junction of Beijing,Tianjin and Hebei province.The continental climate is characterized by four distinct seasons and abundant plant species.In recent years,due to natural factors and human activities,the freshwater wetland ecosystem in Baiyangdian has been severely damaged.AM(arbuscular mycorrhiza)fungi and the vast majority of vascular plant root can form mutual benefit symbionts.Moreover,AM fungi play an important role in plant mineral nutrition,moisture absorption and biological mutual role.Dark septate endophytes(DSE)are a group of small soil fungi,which colonized in plant root cells orintercellular space,and have similar ecological function with arbuscular mycorrhizal fungi.Soil samples and roots of many species of wetland plants were collected on the north shore and in the scenic area of Baiyangdian,Duan village,Anxin county,Baoding in Hebei in May and June,2015.The objective of this work was to study the structural characteristics of AM fungi and DSE within plants,species diversity and community structure of DSE and the screening of cadmium resistant fungal strains form DSE.The results provided important reference value to the development of remedy technology of heavy metals soil pollution.1.In total,20 AM fungal species belonging to 6 genera were isolated from the Baiyangdian wetland plants.Among these fungi,9 species belong to Glomus,6 to Acaulospora,2 to Scutellospora,1 to Funneliformis,1 to Gigaspora and 1 to Archaeospora.2.The results showed that all kinds of plants were associated with AM fungi.The most common morphotype of AM fungi observed was the Arum-type,while Paris type and intermediate AM morphology were also found.3.Compared with those in desert and farmland ecological environments,arbuscular colonization of Baiyangdian wetland plants was significantly higher,but vesicle colonization was significantly lower.The arbuscular abundance was not significantly different compared with tropical plants,while vesicle infection rate was higher than tropical plants,which may be related to the function of arbuscular and vesicular,the result might due to a long-termadaptation environment.4.The results showed that all kinds of plants were associated with DSE.This study indicated that wetland plants of Baiyangdian could be highly infected by DSE,which formed typical dark septate hyphae and “microsclerotia”.Most DSE strains were naturally spore producing,and strains no spore producing were observed with special structures such as hyphal binding point(Mycelium,binging,sites)and hyphal ring(Mycelium,circle).5.By means of morphological identification and molecular identification,5 species were obtained,i.e Altemaria sp.,Exserohilum pedicellatum which were the anamorph of Setosphaeria pedicellata,Cladosporium cladosporioides,Zopfiella latipes,Lasiosphaeria hispida.Among these,Zopfiella latipes,Exserohilum pedicellatum were the anamorph of Setosphaeria pedicellata,Lasiosphaeria hispida was first observed and reported in the freshwater wetland ecosystem of China.6.The resistance of two DSE strains,XHF(Cladosporium cladosporioides)and LWJ1(Altemaria sp.)under cadmium stress were screened out from isolated DSE strains.In a certain concentration range of Cd2+,melanin contents of the two strains were increased with the increase of Cd2+ concentration,which indicated that mycelium melanin contents level of DSE were related to strain cadmium stress resistance.