Host Selective Suppression by Water-Soluble Glucans from Phytophthora spp. of Hypersensitive Cell Death of Suspension-Cultured Cells from Some Solanaceous Plants Caused by Hyphal Wall Elicitors of the Fungi

The suppressor action of water-soluble glucans (WSG) isolated from Phytophthora capsici, P. infestans and P. nicotianae var. nicotianae on hypersensitive cell death caused by elicitors was investigated using suspension-cultured of tomato (Lycopersicon esculentum Mill., L. peruvianum), sweet pepper (Capsicum frutescence L.) and tobacco (Nicotiana tabacum L.). The hypersensitive cell death was caused by elicitor of hyphal wall components (HWC) both from pathogenic and nonpathogenic Phytophthora spp. and depended on the concentration of the elicitor and duration of treatment. On the other hand, the WSG from respective species of Phytophthora suppressed the elicitor-induced cell death in the manner of host selectivity: the suppressor activity was specific only to its typical host (i.e., P. capsici for sweet pepper, P. infestans for tomato and P. nicotianae var. nicotianae for tobacco) and the common host (tomato). These results suggest that WSG from the above Phytophthora spp. may be involved in the determination of host-selectivity for the establishment of compatible interaction with their respective host plants.