Differences in biochemical, physiological and molecular response mechanisms of rice, weedy rice and barnyardgrass subjected to drought

ABSTRACT The drought stress tolerance may differ among species and cultivars. The drought effect on plants depends on the impact on the plant’s physiological, biochemical and molecular processes, as well as on its ability to adapt under these conditions. This study aimed to evaluate the physiological and biochemical responses, and determine the expression of the genes OsAPX2, OsHSP24.15, OsHSP71.10 and OsHSP85.88 under drought conditions in rice, weedy rice and barnyardgrass. A greenhouse experiment was performed in a complete randomized design, with four replications and two factors: water conditions (well-watered and water deficit) and plant species [rice (Oryza sativa cv. Puitá), weedy rice (Oryza spp.) and barnyardgrass (Echinochloa spp.)]. Under drought conditions, the rice and weedy rice plants showed more cellular damage than the barnyardgrass, and the three species showed a reduced photosynthetic rate. C3 plants (rice and weedy rice) increased the damage to lipids and proteins at 5 days of drought. However, for C4 plants (barnyardgrass), the drought conditions did not affect the biochemical parameters. The expression of the OsHSP85.88 gene increased in the three plants exposed to water deficit.