Transcriptome analysis of various flower and silique development stages indicates a set of class III peroxidase genes potentially involved in pod shattering in Arabidopsis thaliana.

Claudia Cosio,Christophe Dunand

doi:10.1186/1471-2164-11-528

Abstract

BackgroundPlant class III peroxidases exist as a large multigenic family involved in numerous functions suggesting a functional specialization of each gene. However, few genes have been linked with a specific function. Consequently total peroxidase activity is still used in numerous studies although its relevance is questionable. Transcriptome analysis seems to be a promising tool to overcome the difficulties associated with the study of this family. Nevertheless available microarrays are not completely reliable for this purpose. We therefore used a macroarray dedicated to the 73 class III peroxidase genes of A. thaliana to identify genes potentially involved in flower and fruit development.ResultsThe observed increase of total peroxidase activity during development was actually correlated with the induction of only a few class III peroxidase genes which supports the existence of a functional specialization of these proteins. We identified peroxidase genes that are predominantly expressed in one development stage and are probable components of the complex gene networks involved in the reproductive phase. An attempt has been made to gain insight into plausible functions of these genes by collecting and analyzing the expression data of different studies in plants. Peroxidase activity was additionally observed in situ in the silique dehiscence zone known to be involved in pod shattering. Because treatment with a peroxidase inhibitor delayed pod shattering, we subsequently studied mutants of transcription factors (TF) controlling this mechanism. Three peroxidases genes -AtPrx13, AtPrx30 and AtPrx55- were altered by the TFs involved in pod shatter.ConclusionsOur data illustrated the problems caused by linking only an increase in total peroxidase activity to any specific development stage or function. The activity or involvement of specific class III peroxidase genes needs to be assessed. Several genes identified in our study had not been linked to any particular development stage or function until now. Notably AtPrx13, which is one of the peroxidase genes not present on commercially available microarrays. A systematic survey of class III peroxidase genes expression is necessary to reveal specific class III peroxidase gene functions and the regulation and evolution of this key multifunctional enzyme family. The approach used in this study highlights key individual genes that merit further investigation.

Highlights

Plant class III peroxidases exist as a large multigenic family involved in numerous functions suggesting a functional specialization of each gene
We further showed in A. thaliana that when class III peroxidase activity was inhibited pod shattering was delayed
Our data illustrate the difficulty in interpreting total peroxidase activity data when trying to link it to specific functions

Summary

Introduction

Plant class III peroxidases exist as a large multigenic family involved in numerous functions suggesting a functional specialization of each gene. Genes encoding secreted class III plant peroxidases (EC 1.11.1.7) are present in all land plants and form large multigenic families [1]. In their regular peroxidative cycle, class III peroxidases catalyze the reduction of. The great number of plant peroxidases genes, the diversity of the processes catalyzed by them, as well as the presence of both highly conserved domains and variable parts in all their sequences suggest the existence of a functional specialization of these proteins [7]. It is imperative to link each individual gene with a precise role for a better understanding of the functions, the regulation and the evolution of this key multifunctional enzyme family

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