Genome-wide identification of GH3 genes in Brassica oleracea and identification of a promoter region for anther-specific expression of a GH3 gene

Jiseong Jeong,Sunhee Park,Hankuil Yi,Jeong Hui Im

doi:10.1186/s12864-020-07345-9

Abstract

BackgroundThe Gretchen Hagen 3 (GH3) genes encode acyl acid amido synthetases, many of which have been shown to modulate the amount of active plant hormones or their precursors. GH3 genes, especially Group III subgroup 6 GH3 genes, and their expression patterns in economically important B. oleracea var. oleracea have not been systematically identified.ResultsAs a first step to understand regulation and molecular functions of Group III subgroup 6 GH3 genes, 34 GH3 genes including four subgroup 6 genes were identified in B. oleracea var. oleracea. Synteny found around subgroup 6 GH3 genes in B. oleracea var. oleracea and Arabidopsis thaliana indicated that these genes are evolutionarily related. Although expression of four subgroup 6 GH3 genes in B. oleracea var. oleracea is not induced by auxin, gibberellic acid, or jasmonic acid, the genes show different organ-dependent expression patterns. Among subgroup 6 GH3 genes in B. oleracea var. oleracea, only BoGH3.13–1 is expressed in anthers when microspores, polarized microspores, and bicellular pollens are present, similar to two out of four syntenic A. thaliana subgroup 6 GH3 genes. Detailed analyses of promoter activities further showed that BoGH3.13–1 is expressed in tapetal cells and pollens in anther, and also expressed in leaf primordia and floral abscission zones.ConclusionsSixty-two base pairs (bp) region (− 340 ~ − 279 bp upstream from start codon) and about 450 bp region (− 1489 to − 1017 bp) in BoGH3.13–1 promoter are important for expressions in anther and expressions in leaf primordia and floral abscission zones, respectively. The identified anther-specific promoter region can be used to develop male sterile transgenic Brassica plants.

Highlights

The Gretchen Hagen 3 (GH3) genes encode acyl acid amido synthetases, many of which have been shown to modulate the amount of active plant hormones or their precursors
Identical genomic sequences were used for annotation, only 30 B. oleracea GH3 candidate proteins, including two with truncations in GH3 domains, were found to have significant similarities to Arabidopsis GH3s in NCBI database (NCBI, http://ncbi.nlm. nih.gov) [34]
For proteins showing different protein sequences between two databases, such as BoGH3.12–2 and BoGH3.17–1, NCBI protein models were adopted in our study because they are supported by RNA-seq data in NCBI

Summary

Introduction

The Gretchen Hagen 3 (GH3) genes encode acyl acid amido synthetases, many of which have been shown to modulate the amount of active plant hormones or their precursors. The Gretchen Hagen 3 (GH3) gene was first identified in Glycine max (soybean) as an early response gene, which is transcriptionally induced in less than 30 min by treatment of auxin plant hormone [1]. Like acyl CoA synthetases, non-ribosomal peptide synthetases, and luciferases in ANL superfamily proteins, GH3 proteins conjugate combinations of amino acids and acyl acids in two-step reactions [8, 9]. In the first half-reaction involving ATP and acyl acid, adenylated acyl acid is produced and pyrophosphate is released. In the second half-reaction, adenylated acyl acid intermediate reacts with amino acids, resulting in the release of acyl acid-amino acid amido conjugate and adenosine monophosphate. Arabidopsis thaliana (Arabidopsis) GH3.11, jasmonate (JA) resistant 1 (JAR1), and Arabidopsis GH3.17, reversal of sav 2 (VAS2), catalyze the production of JA-isoleucine and indole acetic acid (IAA)–glutamate, respectively [10, 11]

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Conclusion