Taxonomy and Ecology Of Inland Sand Dune ... - Mycorrhizae

12Maser et al., 1978; Allen, 1987). In soil,spores of VAM fungi are protected bytiller or rhizome leaves and scales whichcarry spores with them to new sites.When roots arise at the node of thetillers or the rhizomes, hyphae ofgerminated spores penetrate the youngroots and establish mycorrhizalassociations (Gemma, 1987).The number of VAM fungal spores inthe soil is a good indicator of speciesabundance. VAM fungal spores areusually more numerous and diverse incultivated soils than under naturalvegetation (Gerdemann, 1968; Mosseand Bowen, 1968; Hayman, 1978;Hayman and Stovold, 1978). SinceVAM fungal spores are not easilydispersed from the point of sporulation,the upper 10 cm of soil is the bestindicator of VAM fungal populations(Friese and Koske, 1991).germination occurred by the growth of agerm tube from a peripheral chamberthat was formed between the walls.Further studies showed that chamberswere not formed before germination(Walker, 1987). Berch and Fortin(1983b) studied spore germination inthree genera (Endogone, Gigaspora, andAcaulospora) and suggested that there isa phylogenetic relationship betweenthese three genera based on theformation of an interwall germ tube.There is no published information onspore germination for Sclerocystis orEntrophospora (Walker, 1987). InGlomus spp., spores typically germinateeither by a germ tube that penetratesthrough the subtending hypha or bygerm tubes that emerge directly throughspore wall (Hall, 1977; Walker andRhodes, 1981; Miller and Walker, 1986;Nicolson and Gerdemann, 1968).3. SPORE GERMINATIONB. ASSIMILATIVE STRUCTURESSpore germination in VAM fungi hasbeen studied in only a few species.Mosse (1970) studied spore germinationin Acaulospora laevis. She believed thatVAM fungal hyphae form symbioticassociations with the roots of almost allplant species. Fungal hyphae areefficient in absorbing mineral nutrients,