Rice TCD8 Encoding a Multi-Domain GTPase Is Crucial for Chloroplast Development of Early Leaf Stage at Low Temperatures

SIMPLE SUMMARY: Low temperatures do not favor plant chloroplast development. Although numerous genes have been identified to function in modulating chloroplast development, the function of the multi-domain GTPase under cold stress is still scarce in rice. This study demonstrated the TCD8 encoding the multi-domain GTPase which plays a part in the development of rice chloroplast under lower temperature, suggesting the significance of the cold-inducible TCD8 for cold-responsive gene regulation. ABSTRACT: The multi-domain GTPase (MnmE) is conservative from bacteria to human and participates in tRNA modified synthesis. However, our understanding of how the MnmE is involved in plant chloroplast development is scarce, let alone in rice. A novel rice mutant, thermo-sensitive chlorophyll-deficient mutant 8 (tcd8) was identified in this study, which apparently presented an albino phenotype at 20 °C but a normal green over 24 °C, coincided with chloroplast development and chlorophyll content. Map-based cloning and complementary test revealed the TCD8 encoded a multi-domain GTPase localized in chloroplasts. In addition, the disturbance of TCD8 suppressed the transcripts of certain chloroplast-related genes at low temperature, although the genes were recoverable to nearly normal levels at high temperature (32 °C), indicating that TCD8 governs chloroplast development at low temperature. The multi-domain GTPase gene in rice is first reported in this study, which endorses the importance in exploring chloroplast development in rice.