The YABBY gene family and abaxial cell fate

The establishment of abaxial-adaxial polarity in lateral organs involves factors intrinsic to the primordia and interactions with the apical meristem from which they are derived. Recently, a small plant-specific family of genes, the YABBY gene family, has been proposed to specify abaxial cell fate. Each asymmetric above-ground lateral organ expresses at least one member of the family in a polar manner, and loss- and gain-of-function studies indicate that they are sufficient to specify abaxial cell fate and that they act in both distinct and redundant manners.