Isolation and Identification of Pathogenic Fungi of Carambola Fruit and Study on Their Metabolites

Abstract

In order to understand the types, biological characteristics, and metabolites types of pathogenic fungi in carambola, the typical diseased parts of carambola fruit were collected for fungal isolation by tissue isolation methods. The fungi were identified by morphological and molecular identification methods based on ITS sequencing analysis. The biological characteristics of pathogenic fungi were explored, and metabolites were isolated and purified using liquid chromatography. Their structures were established on the basis of 1H NMR and 13C NMR. The results were as follows: The four strains were identified as Fusarium equiseti, Neopestalotiopsis sp., Schizophyllum commune and Cladosporium cladosporioides. All four strains could cause disease in carambola fruit. The fermentation products of Fusarium equiseti were chemically investigated, leading to the discovery of four compounds, 3,7,9-trihydroxy-1-methyl-6H-dibenzo[b,d]pyran-6-on, 1,4,7-trihydroxy-3,9-dimethoxy-6H-benzo[c]chromen-6-one, lecanoric acid and 7-hydroxy-4-methyl-1(3H)-isobenzofuranone. The results of biological characteristics indicated that the optimal growth temperature for the four pathogenic fungi was 25~28 ℃, and they could all grow within the pH range of 4~10.

Keywords

• carambola
• pathogenic fungi
• separation and purification
• species identification
• pathogenicity
• biological characteristics