Overexpression of Orange Gene (-R115H) Enhances Heat Tolerance and Defense-Related Gene Expression in Rice ( L.).

In plants, the orange () gene plays roles in regulating carotenoid biosynthesis and responses to environmental stress. The present study investigated whether the expression of rice () gene could enhance rice tolerance to heat stress conditions. The gene was cloned and constructed with or -R115H (leading to Arg to His substitution at position 115 on the OsOr protein), and transformed into rice plants. The chlorophyll contents and proline contents of transgenic lines were significantly higher than those of non-transgenic (NT) plants under heat stress conditions. However, we found that the levels of electrolyte leakage and malondialdehyde in transgenic lines were significantly reduced compared to NT plants under heat stress conditions. In addition, the levels of expression of four genes related to reactive oxygen species (ROS) scavenging enzymes (, , , ) and five genes (, , , , ) responded to abiotic stress was showed significantly higher in the transgenic lines than NT plants under heat stress conditions. Therefore, could be exploited as a promising strategy for developing new rice cultivars with improved heat stress tolerance.