Diversity and ubiquity of xylariaceous endophytes in live and dead leaves of temperate forest trees

Abstract

To test the hypothesis that xylariaceous endophytes were ubiquitous on live and dead leaves of various tree species in the field, xylariaceous fungi were isolated from live leaves and bleached and nonbleached portions of dead leaves of a total of 94 tree species in a cool temperate forest in Japan. The biodiversity of xylariaceous endophytes was evaluated as the richness of operational taxonomic units (OTUs) determined by phylogenetic analysis of the nucleotide sequence of the D1/D2 region of the LSU rDNA of fungal isolates. A total of 326 isolates of xylariaceous fungi were isolated from live and dead leaves and classified into 15 OTUs. The three major OTUs, Xylaria sp.1, Nemania sp., and Biscogniauxia sp., accounted for 94% (308 isolates) of the total number of isolates, and were isolated from various live and dead leaves. Xylaria sp.1 was frequently encountered on bleached portions (which were produced due to the selective decomposition of lignin) of dead leaves of broad-leaved deciduous tree species. The results suggest that xylariaceous endophytes did not show host specificity and had a saprobic phase on dead leaves in their life cycles and that Xylaria sp.1 was capable of decomposing lignin in the field conditions.

Diversity and Ecology of Endophytic and Epiphytic Fungi of Tree Leaves in Japan: A Review

“…The proportions of nonsporulating endophytes can be as high as 54 % of total isolates (summarized in Promputtha et al 2005 ). Recently, molecular methods are used to confi rm the identity of not only non-sporulating "morphotaxa" but also sporulating fungal isolates (e.g., Okane et al 2001a ;Osono and Masuya 2012 ;Osono et al 2013 ). Fungal isolates are then clustered into operational taxonomic units (OTUs) at given similarity thresholds of base sequences that are different among studies (Osono 2013 ).…”

“…Hata and Futai ( 1996 ) compared endophytic mycobiota of needles of 45 Pinus species collected in a nursery in Kyoto and contributed greatly to the number of pinaceous trees examined. Four to fi ve tree species in Fagaceae were chosen for the studies of foliar endophytes in Yoshihashi et al ( 2000 ), Naito et al ( 2002 ), Okane et al ( 2003 ), Osono ( 2012 ), and Osono et al ( 2013 ). A suite of publications by Dr.…”

“…Okane et al ( 2001a ) then identifi ed a Guignardia species ( G. endophyllicola , the teleomorph of Phyllosticta capitalensis ) frequently isolated from leaves of multiple ericaceous and other trees. Osono ( 2012 ), Osono and Masuya ( 2012 ), and Osono et al ( 2013 ) contributed to the study of endophytic fungi associated with leaves of tree species in Aceraceae and Betulaceae.…”

“…Recently, Osono ( 2012 ) studied patterns of occurrence of endophytic fungal genera for leaves of 73 deciduous tree species in a cool temperate forest in Kyoto. In the same forest, Osono et al ( 2013 ) examined 94 tree species (38 families) for the diversity and ubiquity of xylariaceous endophytes in live leaves.…”

“…It should be noted that host specifi city at the level of fungal genus does not necessarily assure the specifi city at species level. However, molecular phylogenetic analyses demonstrated the identity as single species and the low host specifi city of Phyllosticta and Xylaria isolated from multiple hosts (Okane et al 2001a ;Okane 2003 ;Wei et al 2007 ;Osono et al 2013 ). The second group includes fungal genera that show some degree of host specifi city.…”