Diversity And Antimicrobial Activity Of Metabolites Of Endophytic Fungi Isolated From Juglans Regia L.

In this study,the different parts of walnut(Juglans regiaL.)(Root,1-year-old twig,2-year-old twig,scapus,leaf and fruit)from three different habitats(Shanyang,Lantian,Yijun)in two seasons were used as materials.Composition,diversity,preference of fungal endophytes and antimicrobial activity were analyzed by the colonization rate(CR),isolation rate(IR),iaolation frequency(IF),Shannon-Weaver biodiversity index(H'),similarity coefficient and inhibition rate.The conclusions were displayed as follows:1.In total 1035 fungal endophytes(99 strains in roots,255 strains in 1-year-old twig,268 strains in 2-year-old twig,229 strains in scapus,131 strains in leaf and 53 strains in fruit)were isolated from 1440 tissues ofJ.regiaL.and classified into 39 genera(5 classes,10 subjects,10 heads)based on morphological and molecular identification.Among them,Deuteromycetes(834 strains),Moniliales(468 strains)was the dominant species on the level of head,which was made up 45.22% of total,then the Mycelia Steriliaand Sphaeropsidales were secondly dominant ones that they were 15.46% and 12.95% of total,accordingly.On the genera level,Alternaria,Ectostroma and Anthina were three dominant ones that they were comprised 24.44%,10.92% and 8.70%,respectively.2.The endophytic fungi isolated in summer(643 strains)were significantly higher than those in spring(392 strains).And the diversity index was 2.02 and 1.46,respectively.The isolation frequency of endophytic fungi was also different in different habitats.Isolation frequencies from high to low were Shanyang(42.32%)> Yijun(30.82%)> Lantian(26.86%).The diversity index of Shanyang,Lantian and Yijun were 1.47,1.07,1.22,respectively.There were some differences in the composition and isolation frequency of endophytic fungi in different parts of J.regia L..The isolation frequencies from high to low were 2-year-old twig(25.89%)>1-year-oldtwig(24.64%)>scapus(22.13%)> leaf(12.66%)> root(9.57%)>fruit(5.12%).The colonization rate of endophytic fungi from high to low were 2-year-old twig(77.78%)>1-year-old twig(77.08%)>scapus(75.00%)> leaf(73.61%)> root(41.67%)> fruit(35.42%).The variation of the isolation rate was different from the colonization rate.And the isolation rate from high to low were 2-year-old twig(93.06%)> leaf(90.97%)> 1-year-old twig(88.54%)> scapus(79.51%)> fruit(36.81%)> root(34.38%).There were also differences in the diversity of different parts of J.regiaL..The endophytic fungi from 2-year-old twig had the highest diversity index(0.97).However,The endophytic fungi from fruit had the lowest diversity index(0.25).From the point of view of similarity,the similarity coefficient between the different seasons,different habitats and different parts were all below 0.5000,which is moderately dissimilar.3.Among the tested 190 endophytic fungi,at least 7.89% of them showed an inhibition rate higher than 75%,2.63% of the total number of tested strains displayed an inhibition rate higher than 55% simultaneously to six pathogens.In terms of suppression effect,the inhibitory effect on Phytophthora capsici and Valsaceratosperma were better,the inhibition rate were more than 55%.While the inhibitory effect on Fusarium graminearum was the worst one with almost no antagonism.The inhibitory rate of endophytic fungi SYS-3-7 to six plant pathogens was over 55%,which was regarded as a candidate one deserving further study.4.The fermentation broth of endophytic fungus SYS-3-7(80mg/mL)displayed different inhibitory effects on Gloeosporium fructigenum,Valsaceratosperma,Fusarium graminearum,Phytophthora capsici,among whichit showed a strong inhibitory effect on Gloeosporium fructigenum,and the inhibition rate was 74.94%.However,the inhibition rate to Valsa ceratosperma,Fusarium graminearumandPhytophthora capsici were under 50%.With the different extraction phase and concentration,the extracts of metabolites of endophytic fungus SYS-3-7 had different inhibitory effects on 3 plant pathogens.At the same concentration,the inhibition rate of ethyl acetate extract on Fusarium graminearum and Phytophthora capsici were higher than that of n-butanol extract.In the same extraction phase,with the concentration increased,the inhibition rate increased.In addition,the inhibition rate of the different extracts with different concentrations on Gloeosporium fructigenum were all above 70%.These results suggested that the different extraction phases possess differences in metabolite types and content with a certain similarity between the inhibitory effects.