Diaporthe species complex occurring on Asparagus kiusianus in Japan

Abstract

In 2016, a new disease caused by the Diaporthe species complex was discovered in “hamatamabouki”, the Japanese wild asparagus (Asparagus kiusianus Makino), in the coastal area of Northern Kyushu. Two distinct fungal species were recorded as causing the brown and oval-shaped lesions shown by the aerial parts of the plants. Diaporthe asparagi (Phomopsis asparagi) was identified based on molecular analysis of the nuclear ribosomal internal transcribed spacers (ITS), while D. unshiuensis, a first report on the genus Asparagus, was identified using the multi-locus sequence analysis of the ITS region, the translation elongation factor 1-alpha (TEF1-alpha) and the beta-tubulin (TUB) genes. The morphological characteristics of these species were observed, most of which being in accordance with previous descriptions. When A. kiusianus plants were exposed to infection by D. asparagi and D. unshiuensis to fulfill Koch’s postulates, both fungal species proved to be pathogenic.