First dimorphic transition is induced by volatile ammonia early after Saccharomyces cerevisiae microcolony origination from one cell. It results in oriented pseudohyphal cell expansion, which leads to unification of adjacent microcolonies to one more numerous entity.
Later induced dimorphic transition is strictly dependent on Flo11p adhesin and is indispensable for proper formation of biofilm-like aerial 3-D colony structure.