THE DETECTION OF GLOMUS SPP. (ARBUSCULAR MYCORRHIZAL FUNGI) FORMING MYCORRHIZAS IN 3 PLANTS, AT DIFFERENT STAGES OF SEEDLING DEVELOPMENT, USING MYCORRHIZA-SPECIFIC ISOZYMES

A series of glasshouse experiments was used to determine mycorrhiza-sp ecific isozymes (MSIs) produced by five species of Glomus colonizing r oots of a desert shrub legume (Anthyllis cytisoides L.), Thymus vulgar is L. and Allium porrum L. over time. Extracts of colonized roots were electrophoresed on non-denaturing polyacrylamide gels (PAGE) and stai ned for 10 different enzymes. Staining protocols for esterase, glutama te oxaloacetate transaminase, alkaline phosphatase and malate dehydrog enase provided MSIs for the mycorrhizas formed by different arbuscular mycorrhizal (AM) fungi that had colonized roots of the three host pla nts. There was no apparent correlation between levels of colonization or arbuscular intensities, at or between each sampling, and the presen ce of MSIs. The development of colonization by the AM fungi differed l ittle between the three plants when assessed with two methods of estim ating fungal biomass. The variety of MSIs detected might reflect the d iversity of metabolic activities of these Glomus species and, possibly , differing ecological functions. The high-level induction of two alka line phosphatase MSIs in the mycorrhizas of Anthyllis cytisoides colon ized by Glomus microaggregatum BEG56 was used to track the fate of thi s fungus when the same plant was inoculated and transplanted into a se mi-arid site in south-east Spain. The probable fungal origin of the is ozyme was indicated by detection of the same isozyme in the extraradic al mycelium formed by Glomus microaggregatum BEG56 on Allium porrum. T he use of MSIs to detect the mycorrhizas of species of Glomus in colon ized roots is discussed.