Physiological and Molecular Responses in Rice, Weedy Rice and Barnyardgrass Exposed to Supra-Optimal Temperatures

The global temperature to rise 0.3 to 4.8 oC to century. Supra-optimal temperatures can affect plants at different organizational levels, causing morphological, physiological, biochemical and gene expression alterations. Rice, weedy rice, and barnyardgrass may to response differently when subjected to supra-optimal temperatures. Thus, the aimed at determining the physiological response and expression of the genes APX2, HSP24.15 e HSP71.10 in rice, weedy rice, and barnyardgrass when in to supra-optimal temperatures. A greenhouse experiment was conducted in randomized complete desing with four repetitions, with a factorial combination of temperature x plantas, where: factor A consisted of two temperatures (25 oC and 40 oC); and factor B of three plants [rice (Oryza sativa cv. Puitá INTA-CL), weedy rice (Oryza spp.), and barnyardgrass (Echinochloa spp.)]. The 40 oC temperature, in general, caused a reduction in the photosynthesis parameters and in the protein content, and increased the oxidative stress in C3 plants; no damage was observed in the C4 plant subjected to this temperature. In response to the supra-optimal temperatures, rice and weedy rice increased of APX and SOD activity and the expression of OsAPX2, OsHSP24.15 and OsHSP71.10 genes. Barnyardgrass exposed to supra-optimal temperature do not modify the activity of its antioxidant system and increased the OsHSP71.10 gene expression.