Analysis of the WUSCHEL-RELATED HOMEOBOX gene family in the conifer picea abies reveals extensive conservation as well as dynamic patterns.

Harald Hedman,Joel J Sohlberg,Tianqing Zhu,Sara Von Arnold

doi:10.1186/1471-2229-13-89

Harald Hedman, Joel J Sohlberg + Show 2 more

Open Access

https://doi.org/10.1186/1471-2229-13-89

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Abstract

BackgroundMembers of the WUSCHEL-RELATED HOMEOBOX (WOX) gene family have important functions during all stages of plant development and have been implicated in the development of morphological novelties during evolution. Most studies have examined the function of these genes in angiosperms and very little is known from other plant species.ResultsIn this study we examine the presence and expression of WOX genes in the conifer Picea abies. We have cloned 11 WOX genes from both mRNA and genomic DNA and examined their phylogenetic relationship to WOX genes from other species as well as their expression during somatic embryogenesis and in adult tissues.ConclusionsOur study shows that all major radiations within the WOX gene family took place before the angiosperm-gymnosperm split and that there has been a recent expansion within the intermediate clade in the Pinaceae family. Furthermore, we show that the genes from the intermediate clade are preferentially expressed during embryo development in Picea abies. Our data also indicates that there are clear orthologs of both WUS and WOX5 present in the P. abies genome.

Highlights

Members of the WUSCHEL-RELATED HOMEOBOX (WOX) gene family have important functions during all stages of plant development and have been implicated in the development of morphological novelties during evolution
One WOX gene is found in the genomes of the green micro algae Ostreococcus tauri and O. lucimarinus, three WOX genes are present in the genome of the moss Physcomitrella patens, nine in the lycophyte Selaginella moellendorffii, whereas the genome of A. thaliana contains 15 WOX genes
The P. abies WOX genes were named according to their closest homolog in A. thaliana as indicated by phylogenetic analyses except for PaWOX8A, PaWOX8B, PaWOX8C, and PaWOX8D, which were named after AtWOX8, which is the A. thaliana gene in the intermediate clade with the lowest number, and A-D because the P. abies genes are more similar to each other (65% average pairwise identity, see Additional file 1) than they are to any A. thaliana genes

Summary

Introduction

Members of the WUSCHEL-RELATED HOMEOBOX (WOX) gene family have important functions during all stages of plant development and have been implicated in the development of morphological novelties during evolution. In angiosperms members of the WUSCHEL-RELATED HOMEOBOX (WOX) gene family play important roles determining cell fates during plant development. The WOX gene family is characterised by the phylogenetic relationship of the homeodomain of these genes It is present only in the “green” lineage comprising land plants and green algae. One clade contains genes from early diverging plants, e.g. the moss P. patens, as well as the green algae O. tauri and O. lucimarinus, and this clade is referred to as the ancient clade [1]. The other two clades are termed the intermediate clade, containing AtWOX8, 9, 11 and 12, and the modern clade, containing AtWUS and AtWOX1-7 [1]

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