Diversity Of Arbuscular Mycorrhizal Fungi Associated With Prunus Mume In China

Prunus mume Sieb.et Zucc.is a famous ornamental and fruit tree,distributed in fifteen provinces of southern areas,and cultivated in almost all parts of China.The anthesis of P.mume is the earliest among all floras in nature,and the history of its application and cultivation is for a long time in China.The study of diversity of arbuscular mycorrhizal fungi(AMF) associated with P.mume in China was carried out,in order to explore AM colonization,species and ecological distribution of AMF.Rhizosphere soil and root samples were collected from both the main distributions and P.mume gardens in China.Spores of AM fungi were isolated from 100 g air-dried soil for each soil sample using the wet-sieving and decanting method,observation of AM structure using the root staining method,and molecular diversity of AMF was analysed based on AFLP marker.The main results are as follows:1.AM structures,i.e.vesicles,entry points,Arum-type arbuscules,hyphal coils,and non-septate hyphae,were present and measured in all samples.The indexes of AM colonization in fine root were significantly higher than that of moderate and thick root,in a range of 8.39～32.22%.The colonization rates were various among different sites,and also various for the colonization among four seasons, being highest in spring sample root.2.A total of 99 morphospecies belonging to 11 genera were isolated from all sample soils.Among them,there were 89 species identified,occupying 43%of the described AMF species in the world,two new species,i.e.Glornus mume and Kuklospora spinosa,were found and 20 new Chinese records were reported.3.AMF species G.claroideurn and G.geosporum were isolated from all 11 sampling sites,and G. rnosseae and G.rubiforme were found from 10 sampling sites.On the other hand,39 species(39.4%) were only isolated from one sampling site,and 24 species(24.2%) were found from two sampling sites. So that,there were wide or limited distributing species for AM fungi associated with P.mume.4.There were 32-38 AMF species / sample site in wild P.mume distribution,only 19-25 species / sample site in Mei cultivar garden.The Shannon-Weiner diversity index(H) of AMF isolated from Tibet, Szechwan and Yunnan,in the wild P.mume distribution core,was 2.68,2.62 and 2.53,which were the three highest values in the 11 sample sites.They could divided into four groups according to the hierarchical cluster analysis based on AMF Shannon-Weiner diversity index(H),spore density(SD), species richness(SR),species and genus number.5.It was positive correlation between AMF Shannon-Weiner diversity index(H) and sample altitude, spore density(SD) and altitude,species richness(SR) and organic matter or organic N,but it was negative correlation between H and sample longitude.Only seven factors,i.e.sample longitude(x₁), latitude(x₂),altitude(x₃),pH(x₄),total P(x₅),organic P(x₆),organic N(x₇) were direct effected the H, SD and SR of AMF based on path analysis.The optimization curve estimation regression model was made as follow:H=50.085-0.025 x₁+0.006 x₂+0.0000515 x₃-0.031 x₄+0.18 x₅+0.0000562 x₆SD=5710.333+0.342x₁-70.884x₂+0.088x₃-170.629x₄-1080.973x₅-0.602 x₆-0.158x₇SR=-300.776+00.299 x₁-0.131 x₂+0.002 x₃+0.754 x₄+00.934 x₅-0.01 x₆+0.011 x₇6.There were some specialties for the AMF community in an extremity environment.AMF most frequently isolated were small(Mean spore diameter≤100μm) and sporocarpic species in karst area in Guizhou,but species of Acaulospora were most frequently found and Acaulospora was one of the dominant genus in southeast Tibet.7.The seasonal dynamics of arbuscular mycorrhizal(AM) fungi associated with P.mume cultivated in Beijing was carded out.There were 17 species in spring,16 species in summer,12 species in winter, and only 10 species in autumn,and Sorenson similarity coefficient was less than 0.42 among seasons in the taxonal level.The result of the changing AMF community between spring and autumn in Wuhan Mei Garden,spring and summer in southeast Tibet also showed that the Shannon-Weiner diversity index (H) was higher in spring.8.Molecular diversity of AMF was analyzed,by DNA amplification by nested PCR based on AFLP marker.The results showed that there were average values of 6.5 polymorphic loci in the AMF DNA from sample soils,more than 3 polymorphic loci from roots.The number of polymorphic loci from soil AMF DNA was similar with the number of AMF species isolated from soil.The clustered groups of AMF DNA by AFLP marker from the roots of different cultivars of P.mume were not equal to cultivar groups.