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Serpula himantioides is a globally distributed wood decay fungus that causes heartwood decay in several tree species. We investigated the occurrence of S. himantioides fruiting bodies in Japan for two years and six months to characterize their biology. The fruiting bodies matured in autumn and occurred on living Chamaecyparis pisifera, Chamaecyparis obtusa, Larix kaempferi, and Cryptomeria japonica trees, as well as on dead trees and soil. Assessing three circular plots, the incidence of living trees with S. himantioides fruiting bodies was lowest in the plot with the most advanced heartwood decay. Furthermore, fruiting bodies occurred more frequently in the lower slope direction of the trunk. Analysis using the pair correlation function suggested that the spatial distribution pattern of living trees with fruiting bodies may change from intensive to random with heartwood decay progress. Finally, according to generalized linear and generalized linear mixed models, which were used to investigate the factors affecting the development of fruiting bodies in C. pisifera, C. obtusa, and L. kaempferi, no clear relationship was found between the presence or absence of fruiting bodies and heartwood decay. Thus, we suggest that fruiting bodies can occur in healthy living trees as well as in living trees in the early stages of heartwood decay. [ABSTRACT FROM AUTHOR]

Serpula himantioides is a wood-decaying fungal pathogen which is widespread and causes potentially serious butt rot in living trees of numerous coniferous plantation species. This study aimed to quantify S. himantioides in the wood of Sawara cypress (Chamaecyparis pisifera) with butt rot using real-time polymerase chain reaction (real-time PCR). Species–specific primers were designed for the internal transcribed spacer 2 (ITS2) regions of ribosomal DNA (rDNA) of S. himantioides. The specificity of the designed primer set was tested by end-point PCR and amplicon sequencing. End-point PCR assays were positive for S. himantioides and negative for S. lacrymans, which belongs to the same genus as S. himantioides, Coniophora puteana of the same family as S. himantioides, and other wood decay fungi. Taxonomy assignment based on amplicon sequencing detected only Serpula spp., and most of them were identified as S. himantioides. The linearity of the calibration curve for absolute quantification by real-time PCR assays was confirmed in the range from 101 to 108 copies. This molecular assay method using real-time PCR could detect trace amounts of S. himantioides in decayed wood, showing the applicability for early diagnostics of butt rot emergence in forests. [ABSTRACT FROM AUTHOR]