Maize Glossy2 and Glossy2-like Genes Have Overlapping and Distinct Functions in Cuticular Lipid Deposition.

Liza Esther Alexander,Xiaobin Zheng,Basil J Nikolau,Yozo Okazaki,Michael A Schelling,Aeriel Davis,Ludmila Rizhsky,Marna D Yandeau-Nelson,Kazuki Saito

doi:10.1104/pp.20.00241

Liza Esther Alexander, Xiaobin Zheng + Show 7 more

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https://doi.org/10.1104/pp.20.00241

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Abstract

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 the glossy2 (gl2) locus affect the deposition of extracellular cuticular lipids. Sequence-based genome scanning identified a new Gl2 homolog in the maize genome, namely Gl2-like Both the Gl2-like and Gl2 genes are members of the BAHD superfamily of acyltransferases, with close sequence similarity to the Arabidopsis (Arabidopsis thaliana) CER2 gene. Transgenic experiments demonstrated that Gl2-like and Gl2 functionally complement the Arabidopsis cer2 mutation, 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 that Gl2-like requires this catalytic capability to fully complement the cer2 function, but Gl2 can accomplish complementation without the need for this catalytic motif. These findings demonstrate that Gl2 and Gl2-like overlap in their cuticular lipid function, but have evolutionarily diverged to acquire nonoverlapping functions.

Highlights

Part of the Biochemistry, Biophysics, and Structural Biology Commons, Cell and Developmental Biology Commons, Genetics and Genomics Commons, and the Plant Sciences Commons
Prior characterizations of the expression of the Gl2 gene indicate that it is highly expressed in young seedling leaves of maize (Tacke et al, 1995), and this is consistent with the role of this gene in cuticular lipid biosynthesis, as suggested with the glossy phenotype that is presented by mutant alleles (Hayes and Brewbaker, 1928)
The H185A, and I190A point mutants of Gl2-like transgene could not fully complement the cer2-5 chemotype, and reverse the cuticular lipid load on these stems (Fig. 5B). These results demonstrate that the HXXXDX BAHD catalytic motif is not required for the ability of the GL2 protein to functionally replace the CER2 function; this motif is required for the ability of the GL2-LIKE protein to fully replace the CER2 function

Summary

Introduction

Part of the Biochemistry, Biophysics, and Structural Biology Commons, Cell and Developmental Biology Commons, Genetics and Genomics Commons, and the Plant Sciences Commons. Transgenic experiments demonstrated that Gl2-like and Gl2 functionally complement the Arabidopsis cer mutation, with differential influences on the cuticular lipids and the lipidome of the plant, 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 that Gl2-like requires this catalytic capability to fully complement the cer function, but Gl2 can accomplish complementation without the need for this catalytic motif. These findings demonstrate that Gl2 and Gl2-like overlap in their cuticular lipid function, but have evolutionarily diverged to acquire nonoverlapping functions. Were undergraduate research assistants; X.Z. provided technical support in many aspects of the research; B.J.N. conceived the project; all authors contributed to the writing of the article. [OPEN]Articles can be viewed without a subscription

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