Species Diversity Of Endophytic Fungi Associated With Mangroves

Mangroves are woody plant communities which are widely distributed in the tropical and subtropical intertidal zone, and is an important dynamic transition zone connecting the continents and oceans. Mangrove ecological system can provide the necessary habitat for a diverse marine fungus, and become the second major ecological groups of marine fungi. Endophytic fungi are those that exist in healthy plant tissues that have no external symptoms of infection, and these fungi do not cause any pathological changes in the host plant tissues at least in a certain period of time. To some extent, they represent the diversity of fungi and affect community structure and diversity of other species in the ecosystem. In this study, samples of branches and leaves of six common mangrove plants, such as Bruguiera gymnorrhiza,Rhizophora stylosa, Kandelia candel, Aegiceras corniculatum, Avicennia marina and Excoecaria agallocha were collected from Gaoqiao town of Guangdong province,and species diversity and community structure of endophytic fungi from mangroves were researched. The main results as follows:1. 336 strains of 38 species of endophytic fungi from 960 tissues of six mangrove plants were isolated and identified. Of them, 139(41.37% of the total)sporulated and were identified into 16 species by morphological characteristics. The remaining 196(58.63% of the total)failed to sporulate and were divided into 34 morphotypes, and were identified into 22 species according to cultural characteristics,morphological characteristics and the ITS sequences. Pestalotiopsis(67 strains),Phomopsis(30 strains)and Phyllosticta(56 strains)were the dominant strains of six mangrove plants. 336 strains of 38 species of endophytic fungi were all belonged to ascomycetes. Of these fungi, Dothideomycetes were accounting for 52.63%,Sordariomycetes were accounting for 39.47% and Eurotiomycetes were accounting for 7.89%. Moreover, one new record in china was identified and described, i.e.Aspergillus stellifer.2. Significance difference in the total colonization rates(37.5%~79.4%)was found among endophytic fungi associated with six mangrove plants. The colonizationof endophytic fungi of branches was significantly higher than that of leaves for five host plants except for Excoecaria agallocha.3. Some endophytic fungi showed obvious host and tissue specificity, such as Curvularia and Phoma were only isolated from branches of Excoecaria agallocha.Corynespora and Neodevriesia were only isolated from branches of Rhizophora stylosa. Neurospora and Stenella musae were only isolated from leaves of Rhizophora stylosa. Nodulisporium was only isolated from branches of Bruguiera gymnorrhiza.Coniochaeta ligniaria was only isolated from leaves of Avicennia marina and Medicopsis romeroi was only found in branches of Avicennia marina.4. Significance difference of the shannon-wiener index, Simpson index and evenness index of endophytic fungi were found in host and tissue level. From high to low order of the Shannon-Weaver index of endophytic fungi in host level was:Avicennia marina(2.07)> Rhizophora stylosa(1.91)> Aegiceras corniculatum(1.64)> Kandelia candel(1.55)> Excoecaria agallocha(1.45)> Bruguiera gymnorrhiza(1.29). The diversity of endophytic fungi in tissue level: branches >leaves. The number of endophytic fungi increased with the samples number increasing and further illustrated the species diversity of endophytic fungus from mangrove is rich.5. Species diversity and ecological distribution of endophytic fungi from mangrove plants had close relationship with host plant, organ type and ecological environment.The results of community composition and species diversity of endophytic fungi in mangrove have important role for elucidating the relationship between host plants and endophytic fungi, and development and utilization of endophytic fungi resources.