Enhanced high temperature tolerance in transgenic rice seedlings with elevated levels of alternative oxidase, OsAOX1a

The cyanide-insensitive alternative oxidase (AOX) respiratory pathway can reduce the excessive production of reactive oxygen species. Here we showed that transgenic rice seedlings transformed with OsAOX1a for rice alternative oxidase under the control of ubiquitin promoter exhibited thermotolerance after acute exposure, 41-45°C for 10 min, or chronic exposure, 37°C for up to 8 days. In contrast, these high temperature stresses resulted in significant growth inhibition in wild-type and transgenic plants with antisense OsAOX1a. The enhanced tolerance was significant in shoot growth, suggesting that the increased levels of AOX protein would dissipate the excess reductants produced in the chloroplasts suffering from oxidative damage due to high temperature stress.