Exposure of Eucalyptus to varied temperature and CO2 has a profound effect on the physiology and expression of genes related to cell wall formation and remodeling

Climate change may lead to severe losses in agriculture, including wood production. To understand the effects of climate change on physiology and molecular aspects of wood formation, we grew plants of Eucalyptus grandis and E. globulus for 35 days under three temperatures (10–12 °C, 20–22 °C, and 33–35 °C) combined with two CO 2 concentrations (390 and 700 ppm). Biochemical analyses and RNAseq in stems were carried out together with leaf gas exchange measurements. We analyzed in-depth cell wall biosynthesis genes and their regulation by several transcription factors, as well as genes associated with carbon partitioning, cell wall remodeling, and hormonal regulation. E. globulus , a species adapted to low temperature, was more responsive to the treatments than E. grandis . Gene expression was greatly affected by changes in temperature than in CO 2 . The most relevant processes affected by the treatments were related to stress, secondary metabolism, hormonal response, and signaling. Ethylene and auxin biosynthetic genes were upregulated in both species, but more intensely in E. globulus . High CO 2 stimulated lignin biosynthesis genes and increased S-containing oligomers in E. globulus . Genes related to cell wall carbohydrates and lignin were strongly induced by temperature and CO 2 , respectively. Photosynthesis activity and transpiration were highest under high temperature and high temperature + high CO 2 in both species. Our results show that responses of woody plants may be different regarding the temperature at eCO 2 .