Taxonomical studies on Botryosphaeriales in Japan

概要

Fungi in the order Botryosphaeriales include pathogens that parasitize the leaves, fruits, and branches of plants and cause various diseases. These fungi are important plant pathogens globally, as they cause fruit rot, leaf blight, and branch blight in useful trees, such as fruit trees and trees that are used for urban greening and afforestation. In Japan, many tree diseases have been reported to be associated with Botryosphaeriales, but most of the Japanese species in this order have been described based solely on their morphological characteristics, with their molecular phylogenetic positions remaining unclear, highlighting the urgent need to review the Japanese Botryosphaeriales based on new criteria that reflect molecular phylogenetic relationships. Therefore, in this study, I conducted a taxonomic study of Japanese Botryosphaeriales fungi based on their morphological characteristics, culture characteristics, molecular phylogenetic relationships, and pathogenicities.
The taxonomy of the species in the genus Phyllosticta, which are parasitic on conifer(Cupressaceae) trees in Japan, was conducted based on current criteria, including morphological characteristics, culture characteristics, phylogenetic relationships, and pathogenicities. Phylogenetic analyses revealed that this genus included several clades comprising plant pathogens that were isolated from a specific host as well as clades comprising endophytic species isolated from various conifer species. Each clade was recognized as a species based on the morphological characteristics and other features. Five species of Phyllosticta sensu stricto were recognized, two of which were newly recorded in the Japanese mycoflora. Furthermore, a new combination of P. pilospora and its epitype and an epitype and ex-type strain for P. cryptomeriae were proposed.
To clarify the species diversity of Lasiodiplodia in Japan, I examined 30 Japanese isolates based on their morphological characteristics, culture characteristics, and phylogenetic relationships. Phylogenetic analyses using a matrix composed of ITS, tef1-α, tub2, and rpb2 sequences revealed that these isolates were divided into 11 clades that corresponded to L. theobromae, L. brasiliensis, L. swieteniae, L. pseudotheobromae, andLasiodiplodia spp. These species were also identified based on their morphological characteristics and the optimum growth temperature of each isolate, two of which were new additions to the Japanese mycoflora. In addition, four other species (L. latispora, L.parvispora, L. ryukyuensis, and L. yaguchii) were proposed.
Reexamination of Japanese species in the genus Botryosphaeria isolated from 12 plant species belonging to ten families was carried out based on their morphological characteristics and molecular and phylogenetic analyses using the tef1-α, tub2, and rpb2 protein-coding regions and the ITS region of rDNA. These Japanese isolates were divided into five clades that were identified as B. dothidea, B. qingyuanensis, B. sinensis, andBotryosphaeria sp. Among these, B. qingyuanensis and B. sinensis have recently beenadded to the Japanese mycoflora and are not host-specific. In addition, B. tenuispora isolated from Leucothoe fontanesiana and insect galls on the leaves of Aucuba japonica was proposed as a new species.
Reexamination of Japanese species in the genus Neofusicoccum was carried out based on their morphological characteristics and molecular phylogenetic relationships using the ITS, rpb2, tef1-α, and tub2 regions. These Japanese isolates were divided into five clades, which were recognized as the species N. parvum, other Neofusicoccum spp., and three new species proposed in this study (N. hyperici, N. miyakoense, and N.okinawaense). In addition, Physalospora laricina, which causes shoot blight in larch, was transferred to the genus Neofusicoccum and its epitype and ex-epitype isolates were proposed.
their roles as plant pathogens, endophytes, and saprophytes in ecosystems.