Plant viruses and viroids in Japan

An increasing number of plant viruses and viroids have been reported from all over the world due largely to metavirogenomics approaches with technological innovation. Herein, the official changes of virus taxonomy, including the establishment of megataxonomy and amendments of the codes of virus classification and nomenclature, recently made by the International Committee on Taxonomy of Viruses were summarized. The continued efforts of the plant virology community of Japan to index all plant viruses and viroids occurring in Japan, which represent 407 viruses, including 303 virus species and 104 unclassified viruses, and 25 viroids, including 20 species and 5 unclassified viroids, as of October 2021, were also introduced. These viruses and viroids are collectively classified into 81 genera within 26 families of 3 kingdoms (Shotokuvirae, Orthornavirae, Pararnavirae) across 2 realms (Monodnaviria and Riboviria). This review also overviewed how Japan’s plant virus/viroid studies have contributed to advance virus/viroid taxonomy

Automated Ribosomal Intergenic Spacer Analysis to Detect Pathogenic Fungi in Dark-Colored Spots on Apple Fruits

Dark-colored spots (DCSs) found on apples at harvest time worldwide significantly reduce the commercial value of the fruits. In this study, we conducted an automated ribosomal intergenic spacer analysis (ARISA) to reliably detect fungal pathogens in these lesions. The fragment sizes of peaks for eight species and two species complexes that might cause DCSs on apples in northern Honshu Island, Japan, were determined on the basis of the ARISA. The fragment sizes for six species (Botryosphaeria kuwatsukai, Diplocarpon mali, Mycosphaerella pomi, Neonectria galligena, Phlyctema vagabunda, and Venturia inaequalis) were unique, enabling their detection in a single ARISA trial. However, two other species and two species complexes had similar fragment sizes. To identify these fungi, PCR amplifications using species- or genus-specific primers were needed. Using this method to examine the fresh tissue of DCSs (i.e., after removing the epidermis) on commercially produced apples resulted in the detection of six fungal species and two Colletotrichum species complexes. Because the pathogenic fungi in the tissue underlying lesions are most likely the causal agents, these fungi could be responsible for the DCSs on apple fruits. An automated analysis of the PCR products amplified for the ARISA enables the rapid examination of many samples. These results indicate that the ARISA-based technique developed in the present study is useful for the accurate, reliable, and comprehensive detection of the pathogens causing DCSs on apple fruits. [Graphic: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license