Proteins responding to drought and high-temperature stress in Populus x euramericana cv. '74/76'

Proteomic analysis provides a powerful method of studying plant responses to stress at the protein level. In order to study stress-responsive molecular mechanisms for Populus x euramericana cv. '74/76', one of the most important forest plantation tree species in subtropical and temperate regions, we analyzed the response of 2-year-old cuttings of P. x euramericana cv. '74/76' to drought and high temperature using two-dimensional gel electrophoresis. More than 1,000 reproducible leaf proteins were detected in the controls and treatments, and 26 proteins were found to change notably in abundance. We identified 13 proteins affected by drought stress and 11 proteins affected by high temperature. These proteins are mainly involved in photosynthesis such as ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit and putative photosystem I reaction center subunit II precursor, and detoxification (manganese superoxide dismutase and methionine sulfoxide reductase A). Furthermore, the level of the photosynthesis proteins affected greatly by the imposed stress conditions was consistent with the observed noticeable decrease in net photosynthesis rate. These studies provides a fundamental data for future research on responses to drought and high temperature, two major factors limiting the growth of forest trees during summer under recent climatic warming.