Conserved and differential transcriptional responses of peroxisome associated pathways to drought, dehydration and ABA.

Heba T Ebeed,Sean R Stevenson,Alison Baker,Andrew C Cuming

doi:10.1093/jxb/ery266

Heba T Ebeed, Sean R Stevenson + Show 2 more

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https://doi.org/10.1093/jxb/ery266

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Abstract

Plant peroxisomes are important components of cellular antioxidant networks, dealing with ROS generated by multiple metabolic pathways. Peroxisomes respond to environmental and cellular conditions by changing their size, number, and proteomic content. To investigate the role of peroxisomes in response to drought, dehydration and ABA treatment we took an evolutionary and comparative genomics approach. Colonisation of land required evolution of dehydration tolerance in the absence of subsequent anatomical adaptations. Therefore, the model bryophyte Physcomitrella patens, the model dicot Arabidopsis thaliana and wheat (Tricitcum aestivum), a globally important cereal crop were compared. Three sets of genes namely 'PTS1 genes' (a proxy for genes encoding peroxisome targeted proteins), PEX genes (involved in peroxisome biogenesis) and genes involved in plant antioxidant networks were identified in all 3 species and their expression compared under drought (dehydration) and ABA treatment. Genes encoding enzymes of β-oxidation and gluconeogenesis, antioxidant enzymes including catalase and glutathione reductase and PEX3 and PEX11 isoforms showed conserved up-regulation, and peroxisome proliferation was induced by ABA in moss. Interestingly, expression of some of these genes differed between drought sensitive and resistant genotypes of wheat in line with measured photosynthetic and biochemical differences. These results point to an underappreciated role for peroxisomes in drought response.

Highlights

Water deficiency is a severe constraint on crop production world-wide (Boyer, 1982)
Three sets of genes namely ‘PTS1 genes’, PEX genes and genes involved in plant antioxidant networks were identified in all 3 species and their expression compared under drought and Abscisic Acid (ABA) treatment
Three sets of genes associated with peroxisome biogenesis and function were identified in wheat and moss using the corresponding Arabidopsis proteins as queries.These 3 gene sets coded for i) proteins carrying a predicted peroxisome targeting signal type 1 (PTS1) sequence at the C-terminus (‘genes of putative PTS1 proteins’) ii) enzymes involved in the cellular antioxidant network that had been described as peroxisomal, their non-peroxisomal homologs and some additional non-peroxisomal antioxidant enzymes (‘Antox proteins’) and iii) PEX genes involved in peroxisome biogenesis

Summary

Introduction

Water deficiency is a severe constraint on crop production world-wide (Boyer, 1982). For example drought regularly limits wheat production in almost 50% of the cropped area. Exogenous application of ABA induces a number of genes that respond to dehydration and cold stress (Zhu, 2002; Shinozaki et al, 2003; Cuming et al, 2007) not all genes that are induced by dehydration and cold stress respond to the exogenous application of ABA (Zhu, 2002;Yamaguchi-Shinozaki and Shinozaki, 2006). This suggests the existence of ABA-independent and ABA-dependent signal transduction pathways that convert the initial stress signal into cellular responses (Zhu, 2002)

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