FLO11 gene length and transcriptional level affect biofilm-forming ability of wild flor strains of Saccharomyces cerevisiae

In Saccharomyces cerevisiae, FLO11 encodes an adhesin that is associated with different phenotypes, such as adherence to solid surfaces, hydrophobicity, mat and air-liquid biofilm formation. In the present study, we analysed FLO11 allelic polymorphisms and FLO11-associated phenotypes of 20 flor strains. We identified 13 alleles of different lengths, varying from 3.0 to 6.1 kb, thus demonstrating that FLO11 is highly polymorphic. Two alleles of 3.1 and 5.0 kb were cloned into strain BY4742 to compare the FLO11-associated phenotypes in the same genetic background. We show that there is a significant correlation between biofilm-forming ability and FLO11 length both in different and in the same genetic backgrounds. Moreover, we propose a multiple regression model that allows prediction of air-liquid biofilm-forming ability on the basis of transcription levels and lengths of FLO11 alleles in a population of S. cerevisiae flor strains. Considering that transcriptional differences are only partially explained by the differences in the promoter sequences, our results are consistent with the hypothesis that FLO11 transcription levels are strongly influenced by genetic background and affect biofilm-forming ability.