Soil water stress affects both cuticular wax content and cuticle-related gene expression in young saplings of maritime pine (Pinus pinaster Ait)

Grégoire Le Provost,Céline Lalanne,Frédéric Danjon,Christophe Plomion,Frédéric Domergue,Antoine Grosbois,Jean-Marc Gion,Céline Meredieu,Didier Bert,Patricio Ramos Campos

doi:10.1186/1471-2229-13-95

Abstract

BackgroundThe cuticle is a hydrophobic barrier located at the aerial surface of all terrestrial plants. Recent studies performed on model plants, such as Arabidopsis thaliana, have suggested that the cuticle may be involved in drought stress adaptation, preventing non-stomatal water loss. Although forest trees will face more intense drought stresses (in duration and intensity) with global warming, very few studies on the role of the cuticle in drought stress adaptation in these long-lived organisms have been so far reported.ResultsThis aspect was investigated in a conifer, maritime pine (Pinus pinaster Ait.), in a factorial design with two genetic units (two half-sib families with different growth rates) and two treatments (irrigated vs non-irrigated), in field conditions. Saplings were grown in an open-sided greenhouse and half were irrigated three times per week for two growing seasons. Needles were sampled three times per year for cuticular wax (composition and content) and transcriptome (of 11 genes involved in cuticle biosynthesis) analysis. Non-irrigated saplings (i) had a higher cuticular wax content than irrigated saplings and (ii) overexpressed most of the genes studied. Both these trends were more marked in the faster growing family.ConclusionsThe higher cuticular wax content observed in the non-irrigated treatment associated with strong modifications in products from the decarbonylation pathway suggest that cuticular wax may be involved in drought stress adaptation in maritime pine. This study provides also a set of promising candidate genes for future forward genetic studies in conifers.

Highlights

The cuticle is a hydrophobic barrier located at the aerial surface of all terrestrial plants
Plant material and drought stress application The main goal of this study was to investigate the role of the cuticle in the drought stress response of maritime pine saplings and its relationship to growth performance
As in the 2008 growing season, the other four genes (CER6, CER10, CER2 and LACS3) were most strongly expressed in July, in the “V+” family plants subjected to the non-irrigated treatment (Figure 4)

Summary

Introduction

The cuticle is a hydrophobic barrier located at the aerial surface of all terrestrial plants. Recent studies performed on model plants, such as Arabidopsis thaliana, have suggested that the cuticle may be involved in drought stress adaptation, preventing non-stomatal water loss. The cuticle is the outermost layer of the aerial parts of the plant This protective coat is synthesized exclusively by epidermal cells and has two major constituents: cutin, a lipophilic polymer, and cuticular waxes, which are embedded in and cover the cutin. Cuticular waxes are principally involved in limiting non-stomatal water loss and constitute a key adaptation in the evolution of land plant [6,10]. The overexpression of a transcription factor involved in cuticular wax regulation (i.e. SHINE) has been shown to increase cuticular wax deposition and enhance drought tolerance in both Arabidopsis thaliana [15] and Medicago sativa L. The overexpression of a transcription factor involved in cuticular wax regulation (i.e. SHINE) has been shown to increase cuticular wax deposition and enhance drought tolerance in both Arabidopsis thaliana [15] and Medicago sativa L. [16]

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