Mycorrhizal symbiosis enhances Phalaenopsis orchid’s growth and resistance to Erwinia chrysanthemi

Phalaenopsis is the most important potted orchid genus in the world. However, the low seedling survival rate, long vegetative growth period and disease outbreak are problems in production. Orchid micorrhizal fungi (OMF) are their obligate partners in orchid physiology. Orchids use their symbionts to gain access to organic and mineral nutrients by increasing nutrient absorption and translocation to plants under natural conditions. The benefit of orchid mycorrhizal symbiosis using Phalaenopsis as model plants was conducted. We inoculated in vitro grown plantlets of Doritaenopsis Taisuco Wonder ‘King Car Butterfly KC1111’ and Phalaenopsis Tai Lin Redangel ‘V31‘ with two OMF isolates, Ceratobasidium sp. AG-A (R02) and Rizoctonia solani AG-6 (R04). The effects of OMFs on orchid plant growth and Erwinia soft rot progression were examined after two months of ex vitro growth. The results showed that the presence of OMFs in Phalaenopsis roots significantly increased the growth and soft rot resistance of plants. Selectivity of cultivar type to different OMF was also observed. The relevance of this findings and future work are discussed.Key words: Phalaenopsis, orchid micorrhizal fungi, orchid, cultivar type