Auxiliary Cells Clusters of thin-walled cells which branch from extraradical hyphae of fungi in the suborder Gigasporineae . They appear to peak at or within a short period after onset of sporulation in pot cultures. They often are in low numbers or absent in pot cultures over 4 months old in age. Spores Spores are differentiated either in soil or in roots in all genera except Gigaspora . We, and researchers in Lyn Abbott's lab, have experimental results indicating sporulation occurs only after a critical threshold level of fungal biomass is established in roots.
Sporulation then progresses asynchronously thereafter along with continued mycorrhizal development.
In pot cultures, sporulation ceases with root growth in species of Glomaceae and Acaulosporaceae but may continue to occur at low levels in species of Gigasporaceae . Spores of all arbuscular fungi are assumed to be infective once they form one or more germ tubes.