A cytokinin oxidase/dehydrogenase gene OsCKX4 integrates cytokinin and auxin signaling to control rice crown root formation
| 作者： |
Shaopei Gao,Jun Fang,Fan Xu,Wei Wang,Xiaohong Sun,Jinfang Chu,Baodong Cai,Yuqi Feng and Chengcai Chu |
| 刊物名称： |
Plant Physiology |
| DOI： |
|
| 联系作者： |
|
| 英文联系作者： |
|
| 发表年度： |
2014-05-09 |
| 卷： |
|
| 摘要： |
Crown roots constitute the majority of the rice root system, and play an important role in rice growth and development. However, the molecular mechanism of crown root formation in rice is still not well understood. Here, we characterized a rice dominant mutant, root enhancer1 (ren1-D), which was observed to exhibit a more robust root system, increased crown root number, and reduced plant height. Molecular and genetic analyses revealed that these phenotypes are caused by the activation of a cytokinin oxidase/dehydrogenase (CKX) family gene, OsCKX4. Subcellular localization demonstrated that OsCKX4 is a cytosolic isoform of CKX. OsCKX4 is predominantly expressed in leaf blades and roots, and it is the dominant CKX preferentially expressed in the shoot base where crown root primordia are produced, underlining its role in root initiation. OsCKX4 is induced by exogenous auxin and cytokinin in the roots. Furthermore, one-hybrid assays revealed that OsCKX4 is a direct binding target of both auxin response factor OsARF25 and the cytokinin response regulators ORR2 and ORR3. Overexpression and RNAi of OsCKX4 confirmed that OsCKX4 plays a positive role in crown root formation. Moreover, expression analysis revealed a significant alteration in the expression of auxin-related genes in the ren1-D mutants, indicating that the OsCKX4 mediates crown root development by integrating the interaction between cytokinin and auxin. Transgenic plants harboring OsCKX4 under the control of a root-specific promoter RCc3 displayed enhanced root development without affecting their shoot parts, suggesting that this strategy could be a powerful tool in rice root engineering. |
| 参与作者： |
|
