Endophytic Fungi Diversity Of Five Aquatic Plants And Their Metabolites

Fungi causing asymptomatic infections in living plant tissues have been called fungal endophytes. Large amounts of research have showed the diversity of endophytic fungi and their secondary metabolites. In this study, the diversity of endophytic fungi of 5 aquatic plants Ottelia acuminata (Gagnep.) Dandy, Myriophyllum verticillatum L., Equisetum arvenwe L., Cardamine multijuga. and Impatiens chinensis L., and the pigments of strain C2 have been studied.214 endophytic fungi were isolated from 500 segments of 5 aquatic plants. The average colonization frequency of 5 aquatic plants was 36% and there were significant differences in the colonization frequency of endophytes between the five plant species (X-2=51.128, P<0.001, Chi-square test). The colonization frequency of Ottelia acuminata (Gagnep.) Dandy, Myriophyllum verticillatum L., Equisetum arvenwe L., Cardamine multijuga. and Impatiens chinensis L. were18%,28%,63%,30% and 41%, respectively. In general, The riparian plants harboured more endophytes than the submerged plants. They were identified to 31 taxa in which Cladosporium, Fusarium and Geotrichum were the dominant genera. Among all isolates, 169 (79%) were mitosporic fungi,1 (0.5%) was ascomycete and 44 (21%) were sterile mycelia.The antifungal activity of these isolates against Fusarium solani and Phytophthora nicotianae in vitro were tested.96 (46.9%) isolates were activitive against one or more phytopathogens.28(13.1%) isolates showed antifungal activities with more than 30% growth inhibition rate against 2 pathogens.The antagonistic activities of endophytic fungi of Equisetum arvenwe L., Impatiens chinensis L. and Myriophyllum verticillatum L. metabolites against 6 isolates of plant pathogenic fungi were tested on the medium, and 37(23.9%) isolates were activitive against one or more phytopathogens. The percentage of antifungal active isolates from E. arvenwe L., I. chinensis L. and M. verticillatum L. were 13.9%,29.2% and 37.1%, respectively. It was lower than that of terrestrial plants. The active isolates were mainly belonging to 5 genera including Cladosporium, Trichoderma and Geotrichum. In present study, two anthraquinone compounds have been isolated from the strain C2, an endophytic fungus of C. multijuga. Based upon spectral data and by compared with literature, the structures of the compounds were elucidated. Ccrmal was skyrin(1,1',6,6', 8,8'-hexahydroxy-3,3'-bianthraquinone), Ccrma2 was emodin (1,6, 8-Trihydroxy-3-methylan-thraquinone).C2 was identified to be cryphonectria radicalis based on morphology and its ITS sequence analysis (Gene Bank accession number was GU109283).