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 degrees C 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 supraoptimal 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 degrees C and 40 degrees C); and factor B of three plants [rice (Oryza sativa cv. Puita INTA-CL), weedy rice (Oryza spp.), and barnyardgrass (Echinochloa spp.)]. The 40 degrees C 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 supraoptimal 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.