Table 1. Cell cycle and ECM genes from diverse eukaryotes regulate the unicellularity/multicellularity switch.

Species	Type of multicellularity	Gene required for the unicellular/multicellular switch*	Gene function
Gonium pectoral (green alga)	Clonal	retinoblastoma	Cell cycle (transcriptional repressor) (2)
Saccharomyces cerevisiae (fungus)	Aggregative (flocculation)	flo1, flo5, flo8, flo9, flo10, flo11, sta1	ECM (flo1, flo5, flo9, flo10, flo11: lectins, sta1: endoamylase, flo8: transcriptional activator of the formers) (3–7)
Saccharomyces cerevisiae (fungus)	Clonal (chain and snowflake mutants)	cts1 ACE2	ECM (chitinase) (8) Cell cycle (transcription factor) (9,10)
Dictyostelium discoideum (slime mold)	Aggregative	cbp-26	ECM (lectin) (12,13)
Salpingoeca rosetta (choanoflagellate)	Clonal	rosetteless	ECM (lectin) (11)

^*Some pleiotropic genes are necessary for multicellularity as an indirect effect of them being involved in a more general cell function, such as transcription or cell motility. For example, across the 123 Dictyostelium mutants with aberrant or abolished aggregation (1), most are deficient in transcription, cell movement or cAMP synthesis. These genes are not discussed here as their role is indirect. References: 1. (Glöckner et al. 2016) 2. (Hanschen et al. 2016); 3. (Douglas et al. 2007); 4. (Lo and Dranginis 1996); 5. (Soares 2011); 6. (Stratford 1992); 7. (Fidalgo et al. 2006); 8. (Kuranda and Robbins 1991); 9. (Oud et al. 2013); 10. (Ratcliff et al. 2015); 11. (Shinnick and Lerner 1980); 12. (Ray et al. 1979); 13. (Levin et al. 2014)