Maize Glossy2 and Glossy2-like Genes Have Overlapping and Distinct Functions in Cuticular Lipid Deposition1[OPEN]

Transgenesis dissection of the functional roles of maize Glossy2 and Glossy2-like genes in cuticular lipid deposition reveals both common and distinct functions. Plant epidermal cells express unique molecular machinery that juxtapose the assembly of intracellular lipid components and the unique extracellular cuticular lipids that are unidirectionally secreted to plant surfaces. In maize (Zea mays), mutations at theglossy2 (gl2)locus affect the deposition of extracellular cuticular lipids. Sequence-based genome scanning identified a newGl2homolog in the maize genome, namelyGl2-like. Both theGl2-likeandGl2genes are members of the BAHD superfamily of acyltransferases, with close sequence similarity to the Arabidopsis (Arabidopsis thaliana)CER2gene. Transgenic experiments demonstrated thatGl2-likeandGl2functionally complement the Arabidopsiscer2mutation, with differential influences on the cuticular lipids and the lipidome of the plant, particularly affecting the longer alkyl chain acyl lipids, especially at the 32-carbon chain length. Site-directed mutagenesis of the putative BAHD catalytic HXXXDX-motif indicated thatGl2-likerequires this catalytic capability to fully complement thecer2function, butGl2can accomplish complementation without the need for this catalytic motif. These findings demonstrate thatGl2andGl2-likeoverlap in their cuticular lipid function, but have evolutionarily diverged to acquire nonoverlapping functions.