Effects of water stress and rewatering during tension wood formation on xylem cell differentiation
Résumé
Wood formation is a complex process under both genetic and environmental controls and it is known to be strongly affected by water availability. This study aims to finely describe both wood anatomy and gene expression modifications induced by the sequential application of a water stress followed by a rewatering step on greenhouse-grown poplar plants induced to form tension wood by leaning of their stem. Water stress followed by a rewatering step induced striking modifications in wood anatomy: water stress lead to both a reduction in fibre dimensions and an increase in cell wall thickness, when rewatering induces a transient and strong increase in the vessel/fibre ratio, particularly in tension wood area. This anatomical study has been complemented by a global gene expression analysis using whole poplar genome Affymetrix GeneChip. Transcriptome analysis has been performed on very young xylem tissues collected shortly after rewatering, that is when initial fusiform cells were preferentially oriented toward vessel differentiation. We will present and discuss the results obtained in this experiment.