Table 1.

Functional variation of COM1 homologs observed among grass species.

Species (Name)	Gene function in boundary	GEa on branch formation	GE on pulvinus size/formation	GE on growth of palea cells	GE on number of VBb in palea	GE on Pollen fertilityc
Barley (COM1)	signaling	Inhibition	Absentd	Inhibitione	Promotion	Normal
Brachypodium (BdWAB1/BAD1)	formationf	No effect	Promotion	No effectg	Promotion	Normal
Rice (REP1)	formation	Not reportedh	Promotion	Promotion	Promotion	Reduced
Sorghum (SbWAB1/BAD1)	formation	Promotion	Promotion	No effect	Promotion	Reduced
Maize (WAB1/BAD1)	formation	Promotion	Promotion	Not reported	Not reported	Not reported

^aGE stands for functional gene effect.

^bVB stands for vasculature bundles.

^cRevealed by grain setting measurements as a proxy.

^dPulvinus is typically absent in Wt. spike of Triticeae including barley as well as in the branched mutant spikes.

^eApparent at the longitudinally middle palea part resulting in the formation of the infolding.

^fRefers to the formation of a boundary between pulvinus and the lateral branch without which fusion of the two happened; reflects intermediate evolutionary phylogenetic position of Brachypodium among grasses.

^gNot visible at the microscopic level.

^hPerhaps because the rice cultivars used in the corresponding studies (cv. Nipponbare and cv. 9522) are known to exhibit panicles with acute lateral branches.