Eucalyptus transcriptome analysis revealed molecular chaperones highly expressed in xylem

Background Plant development is very plastic, being coupled to environmental cues. As sessile organisms, plants must be able to respond rapidly to environmental stresses such as changes in temperature and salinity, heavy metals and water deficit. Efficient stress response systems are prerequisites for plant survival and productivity [1]. Molecular chaperones (or Heat Shock Proteins – HSP) compose a ubiquitous class of proteins involved in cellular protein quality control (PQC) and homeostasis. They play a critical role in folding and degradation of polypeptides, and therefore, in maintenance and modulation of cellular pathways, which are dependent of function (correct folding) and availability (stability and degradation) of involved proteins, under normal and stress conditions [2]. Genetics and proteomics studies of wood formation have highlighted some chaperones up-regulated in xylem of Eucalyptus, Pinus and Populus species, stating that they may play an important role in cell wall formation and xylem development [3,4]. Different species of Eucalyptus are known for their superior performance in growth, wood quality and resistance to different types of stress [5]. Such characteristics are probably driven by distinct gene expression coordination in xylogenesis. Eucalyptus grandis is one of the most planted species in the world due to its rapid growth, wide adaptability and wood quality. Eucalyptus globulus wood has higher S/G ratio which provides high yields in cellulose extraction [6]. Lignin extraction consumes large quantities of chemicals and energy, and many efforts have been made to improve this process by modifying lignin content or composition in trees, in order to reduce lignin content or make it easier to extract. Results have been achieved by supplementation and genetic modification [7,8]. This study aims to identify chaperones possibly involved in wood formation and quality of wood for pulp and paper industries.