Molecular characterization of basidiomycetes associated with the decayed mangrove tree Xylocarpus granatum in Thailand

Abstract

This study reports the frequency of decay (stem/butt rot) of Xylocarpus granatum trees at Hat Khanom-Mu Ko Thale Tai National Park, Nakhonsithammarat province, and other locations in Thailand, and the identification of purported causal basidiomycetes based on morphological and molecular analyses. Four survey plots at Hat Khanom-Mu Ko Thale Tai National Park were established and the incidence of butt rot determined. Percentage stem/butt rot incidence of X. granatum trees varied from 40.9 to 94.4 % with an average of 85.5 % along all four Plots. Trees in Plot 2 supported the heaviest incidence rate (94.4 %), with the lowest rate in Plot 3 (40.9 %). Ninety-two basidiomes were collected, and 46 fungal strains (50 %) isolated into axenic culture, the majority associated with tree roots (68.5 % of all collections) with 31.5 % from the tree trunks. Molecular results, based on LSU and ITS1, 2, 5.8 S rDNA analyses, confirmed that all samples belonged to the poroid genus Fulvifomes in the Hymenochaetaceae within the Hymenochaetales, Basidiomycota. The 43 specimens sequenced grouped into three clades; one clade comprised specimens isolated from only the trunks and branches (14 strains), while the remainders were from roots (29 strains) and shown to be salt tolerant. The stem/butt rot strains formed unique phylotypes which did not group with other known Fulvifomes species.