Competitive antagonistic action of laccase between Trichoderma species and the newly identified wood pathogenic Ganoderma camelum

Abstract

<i>Ganoderma</i>, a well-known genus in the Ganodermataceae family, has caused the extinction of several tree species due to its pathogenicity. This study explored the pathogenic effect of a newly identified <i>Ganoderma</i> species on trees and its competitive efficiency against <i>Trichoderma</i> species. <i>Ganoderma camelum</i> sp. nov. is characterized by small sessile basidiomata and a velvety, soft, camel-brown pileus. Phylogenetic analysis and ITS rDNA sequences indicated that the species were <i>Trichoderma</i> and <i>Ganoderma camelum</i>. Both fungal species competed antagonistically by secreting laccase. The laccase activity of <i>G. camelum</i>, with a value of 8.3 ± 4.0 U/mL, demonstrated the highest competitive activity against <i>Trichoderma</i> species. The laccase produced by <i>T. atroviride</i> (2.62 U/mL) was most effective in countering the pathogenic action of the novel <i>G. camelum</i>. The molecular weights of laccase were determined using SDS-PAGE (62.0 kDa for <i>G. camelum</i> and 57.0 kDa for <i>T. atroviride</i>). Due to the white rot induced by this <i>Ganoderma</i> species in the host tree, <i>G. camelum</i> showed the highest percentage inhibition of radial growth (76.3%) compared to <i>T. atroviride</i> (28.7%). This study aimed to evaluate the competitive antagonistic activity of <i>Ganoderma</i> and <i>Trichoderma</i> on malt extract agar media in the context of white rot disease in the host tree. This study concluded that the laccase from <i>G. camelum</i> caused weight loss in rubber wood blocks through laccase action, indicating tissue injury in the host species. Therefore, it was also concluded that <i>G. camelum</i> was more effective in pathogenic action of the host and resisted the biological action of <i>T. atroviride</i>. In principal components analysis (PCA), all the species associated with laccase exhibited a very strong influence on the variability of the system. The PIRG rate (percentage inhibition of radial growth) was strongly and positively correlated with laccase activity.