Identification and Characterization of , a Temperature-Sensitive Mutant Associated with Crown Root Development in Rice.

Crown roots are essential for plants to obtain water and nutrients, perceive environmental changes, and synthesize plant hormones. In this study, we identified and characterized (), which exhibited a defective phenotype of crown root and vegetative development. Temperature treatment showed that was sensitive to temperature and that the mutant phenotypes were rescued when grown under low temperature condition (20 °C). Histological and EdU staining analysis showed that the crown root formation was hampered and that the root meristem activity was decreased in . With map-based cloning strategy, the gene was fine-mapped to an interval of 126.4 kb on chromosome 8. Sequencing analysis revealed that the sequence variations were only found in , which encodes a CC-NBS-LRR protein. Expression and inoculation test analysis showed that the expression level of was significantly decreased under low temperature (20 °C) and that the resistance to () was enhanced in . These results indicated that may be the candidate of and that its mutation activated the plant defense response, resulting in a crown root growth defect.