Fig. 3.

Variation of FLO11 levels and colony morphology.

A. Strains from single tetrads can also exhibit great variety in colony morphology and gene expression. Top, FLO11 gene expression of KV34, KV35, KV36 and KV37, haploids derived from a single tetrad of EM93 diploid strain. Bottom, corresponding photos of the same strains. Both photos and gene expression levels are of colonies grown on YPS agar medium. Scale bar represents 5 mm.

B. De-repressing FLO11 expression increases wrinkliness of a smooth strain. KV34 and KV35 are sister haploid strains derived from the same tetrad of natural isolate strain EM93. KV34 is wrinkly and KV35 is smooth, and this is reflected in the levels of FLO11 expression, with KV34 having higher levels of FLO11. Deletion of SFL1, a repressor of FLO11 expression, raises levels of FLO11 and makes KV35 as wrinkly as KV34. Scale bar represents 5 mm.

C. Increasing FLO11 expression correlates with increasing colony wrinkliness. Replacement of the native FLO11 promoter by a series of constitutive promoters of increasing strength results in a series of strains with increasing wrinkliness. The TEF1prm::FLO11 series was made in the EM93 haploid background. Scale bar represents 5 mm.

D. Flo11 expression correlates with wrinkliness, but is uniform within wrinkly areas of colony. A FLO11–YFP construct was made that incorporated a self-cleaving viral sequence, such that simultaneous expression of Flo11 and YFP was assured without causing interference of Flo11 function. Wrinkly colonies often spawn variants or mutants with smooth morphologies, which results in smooth sectors in growing colonies (arrow in panel D). These sectors are associated with low Flo11 (low YFP) levels. However, closer inspection of wrinkly parts of colonies shows rather homogenous expression of YFP, suggesting that differential expression of FLO11 does not account for patterned growth within a colony (bottom panel).