Oxidative stress proteins as an indicator of a low quality of eucalyptus clones for the pulp and paper industry

Eucalyptus is a genus widely cultivated in many tropical and subtropical regions of the world as one of the main sources of raw materials for the pulp and paper industry. Identification of clones and selection of genotypes with desirable agronomic characteristics would be useful. We assessed eucalyptus full-sibs that varied in wood quality, using a combination of two-dimensional gel electrophoresis and mass spectrometry to identify differentially expressed proteins as candidates for quality markers. Thirty-one differently expressed proteins were identified, including three proteins of clone X1, four of clone X2, and 12 each of clones X3 and X4. These proteins are involved in various biological processes, including polyphosphate biosynthesis, catalytic activity, nucleotide excision repair, cellular metabolic processes, cell redox homeostasis, response to salt stress, response to temperature, oxidation and reduction processes, cellular water homeostasis, and protein phosphorylation. In the cambial region of each clone, the proteins ketol-acid reductoisomerase, uncharacterized protein MG428, receptor-like serine/threonine-protein kinase and a heat shock protein were found in larger quantities in clone X4 than in clone X1. These proteins are known to be related to protection against oxidative stress and biosynthesis of lignin. A high buildup of proteins involved in response to stress in the cambial region of eucalyptus would indicate clones with undesirable characteristics for use in the pulp and paper industry.