Role of cytochrome c in modulating chromium-induced oxidative stress in Oryza sativa.

Cytochrome c (CYTc) is one of the redox-active molecules responsible for electron transport in plant mitochondria. It is important in the interaction of metal ions with mitochondrial proteome, it is also essential for insights into electron transport during oxidative stress. This study focused on the clarification of interactions of CYTc with metal accumulation and associated modulation of CYTc with reactive oxygen species (ROS) generation in rice seedlings exposed to chromium either hexavalent Cr(VI) or trivalent Cr(III). The result indicates that exposures to both Cr species resulted in significant accumulation of Cr in rice tissues. ROS-dependent growth inhibition of rice seedlings was also evident from both Cr treatments. Changes of CYTc content in roots and shoots maintained almost the same pattern after both Cr exposures. However, dynamically transcriptional levels of rice CYTc genes conducted by real-time quantitative RT-PCR were inconsistent in rice tissues. The results presented here demonstrate that oxidative stresses induced by ROS accumulation do not equally and/or detrimentally influence the perturbations of CYTc content and expression patterns of CYTc genes in rice tissues after Cr exposure, suggesting that the decrease of CYTc levels in roots did not originate ROS accumulation, it may be due to metal-binding properties, while enhancement of CYTc content in shoots was probably a signal of severe growth inhibition owing to ROS accumulation.