INTRARADICAL HYPHAE PHOSPHATASE OF THE ARBUSCULAR MYCORRHIZAL FUNGUS,GIGASPORA-MARGARITA

An alkaline phosphatase in the intraradical hyphae of arbuscular mycor rhizal fungi was found to be closely related to an improvement of plan t growth. To detect the phosphatase activity in a crude extract of myc orrhizal roots, phosphatase isozymes in mycorrhizal and non-mycorrhiza l onion roots were compared with those in Gigaspora margarita by elect rophoresis. A mycorrhiza-specific band was found when the phosphatase was stained under alkaline conditions. To clarify the origin of this p hosphatase, the phosphatase extracted from intraradical hyphae was als o compared with the phosphatase from mycorrhizal roots by electrophore sis. The intraradical hyphae was isolated from mycorrhizal roots by en zyme digestion followed by Percoll gradient centrifugation. The solubl e protein was extracted from the hyphae by ultra-sonication after trea tment with chitinase. A phosphatase in the hyphal soluble protein show ed a similar, but slightly higher, relative mobility on the gel, compa red with the mycorrhiza-specific phosphatase from roots. By adding the hyphal extract to the root extract, the relative mobility of the myco rrhiza-specific phosphatase was slightly changed and became identical to that of the phosphatase in the hyphae. This indicated that the spec ific band of phosphatase found in the crude extract from mycorrhizal r oots was of intraradical hyphal origin.