# Orchid diseases caused by Fusarium oxysporum species complex in Taiwan

## TL;DR

This study identifies different types of Fusarium oxysporum causing orchid diseases in Taiwan, focusing on their classification and host preferences.

## Contribution

The study provides a detailed classification of FOSC isolates in Taiwan based on genetic and morphological data.

## Key findings

- FOSC isolates were classified into six taxa using genetic and morphological analyses.
- Terrestrial orchids were the primary hosts for FOSC isolates in this study.
- The findings can help in developing resistant orchid cultivars and management strategies.

## Abstract

Orchid diseases caused by Fusarium spp. are common in orchid gardens worldwide, with F. oxysporum being the most dominant species. F. oxysporum is defined as a species complex, FOSC. In Taiwan, orchids are highly diverse, and certain species are economically important. However, orchid diseases caused by FOSC remain unclear. In this study, 63 FOSC isolates were collected from commercial orchids, including five epiphytic, one semi-terrestrial, and two terrestrial orchids. Terrestrial orchids were the major hosts of isolated FOSC (41/63). The isolates were confirmed to be pathogenic through mycelium plug or spore suspension inoculation, and they were subsequently used for further analyses. Phylogenetic analyses indicated that FOSC isolates could be separated into six taxa, F. contaminatum, F. cugenangense, F. curvatum, F. nirenbergiae, F. odoratissimum, and F. triseptatum, based on cmdA, rpb2, tef1, and tub2 gene sequences. This classification is also associated with morphological characteristics. These results provide a preliminary insight into pathogenic FOSC in orchids and can be used to explore potential resistant cultivars or screen for effective management agents.