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Abstract
BackgroundMembers of the homeodomain-leucine zipper (HD-Zip) gene family encode transcription factors that are unique to plants and have diverse functions in plant growth and development such as various stress responses, organ formation and vascular development. Although systematic characterization of this family has been carried out in Arabidopsis and rice, little is known about HD-Zip genes in maize (Zea mays L.).Methods and FindingsIn this study, we described the identification and structural characterization of HD-Zip genes in the maize genome. A complete set of 55 HD-Zip genes (Zmhdz1-55) were identified in the maize genome using Blast search tools and categorized into four classes (HD-Zip I-IV) based on phylogeny. Chromosomal location of these genes revealed that they are distributed unevenly across all 10 chromosomes. Segmental duplication contributed largely to the expansion of the maize HD-ZIP gene family, while tandem duplication was only responsible for the amplification of the HD-Zip II genes. Furthermore, most of the maize HD-Zip I genes were found to contain an overabundance of stress-related cis-elements in their promoter sequences. The expression levels of the 17 HD-Zip I genes under drought stress were also investigated by quantitative real-time PCR (qRT-PCR). All of the 17 maize HD-ZIP I genes were found to be regulated by drought stress, and the duplicated genes within a sister pair exhibited the similar expression patterns, suggesting their conserved functions during the process of evolution.ConclusionsOur results reveal a comprehensive overview of the maize HD-Zip gene family and provide the first step towards the selection of Zmhdz genes for cloning and functional research to uncover their roles in maize growth and development.
Highlights
The homeobox (HB) gene encodes a highly conserved 60–61 amino acid homeodomain (HD), which confers sequence-specific DNA binding function by folding into a characteristic three ahelix structure [1,2]
Our results reveal a comprehensive overview of the maize homeodomain-leucine zipper (HD-Zip) gene family and provide the first step towards the selection of Zmhdz genes for cloning and functional research to uncover their roles in maize growth and development
Model (HMM) profile were employed as a query to search against the maize genome database with BlastP program
Summary
The homeobox (HB) gene encodes a highly conserved 60–61 amino acid homeodomain (HD), which confers sequence-specific DNA binding function by folding into a characteristic three ahelix structure [1,2]. HD-Zip protein, one group of these proteins, has only been identified in plants far The characteristic of this group is the presence of a HD and an adjacent leucine zipper (Zip) acting as a dimerization motif [5,6]. In Arabidopsis, 48 out of 110 HB genes have been identified as HD-Zip proteins [7,8,9,10,11] Based on their structures, additional specific domains and functions, HD-Zip genes are further categorized into four classes: HD-Zip I-IV [2,12]. Systematic characterization of this family has been carried out in Arabidopsis and rice, little is known about HD-Zip genes in maize (Zea mays L.)
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