A new ‘forma specialis’ of Fusarium solani causing leaf yellowing of Phalaenopsis |
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| Authors: | W C Chung L W Chen J H Huang H C Huang W H Chung |
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| Institution: | 1. Taiwan Seed Improvement and Propagation Station, Hsinhse, Taichung 426;2. Department of Plant Pathology, National Chung Hsing University, Taichung 402;3. Plant Pathology Division, Taiwan Agricultural Research Institute, Wufeng, Taichung 413, Taiwan |
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| Abstract: | The pathogenicity of 35 Fusarium solani isolates obtained from diseased leaves of greenhouse‐grown Phalaenopsis plants in Taiwan was tested on different orchids, including Phalaenopsis sp., Cymbidium spp., Oncidium sp., Dendrobium sp. and Cattleya sp., plus pea (Pisum sativum), chrysanthemum (Chrysanthemum indicum) and cucurbit melon (Cucumis melo) and cucmber (C. sativus)] plants. Isolates of F. solani from Phalaenopsis spp. caused severe leaf yellowing on Phalaenopsis and mild symptoms on Cymbidium spp., but no visual symptoms on Oncidium sp., Dendrobium sp., Cattleya sp., pea, chrysanthemum or melon. Fusarium solani isolates collected from Phalaenopsis, pea and cucurbits were molecularly characterized by internal transcribed spacer (ITS), intergenic spacer (IGS) and β‐tubulin gene analyses. Phylogenetic trees constructed by distance and parsimony methods indicated that isolates from Phalaenopsis were grouped into one type based on ITS, IGS and β‐tubulin sequences with high bootstrap value (> 84%) support, compared to ‘formae speciales’ of F. solani from the other hosts. These analyses show that isolates of F. solani from Phalaenopsis are distinct from F. solani isolates from other hosts in Taiwan. Therefore, it is proposed that F. solani isolates that incite Phalaenopsis leaf yellowing be designated F. solani f. sp. phalaenopsis. |
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| Keywords: | Fusarium solani IGS ITS orchids pathogenicity β ‐tubulin |
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