OsCKX5 Modulates Root System Morphology and Increases Nutrient Uptake in Rice

Cytokinin is a plant hormone and an important regulator of root growth. Reduced cytokinin levels increase root systems, which can be beneficial for crops grown on nutrient poor and/or dry soils. Our study analyzed the effects of increased cytokinin oxidase 5 (OsCKX5) expression in rice roots on root morphology, architecture, and nutrient uptake. We fused the OsCKX5 gene to the strong, root-specific RCc3 rice promoter and overexpressed it in rice plants. The root-specific expression of OsCKX5 in the transgenic plants resulted in positive effects on root development without compromising shoot growth. The root system of the transgenic plants exhibited greater volume, length, projection area, a higher number of tips, and enhanced surface area. OsCKX5 overexpression also resulted in an increased uptake ability of certain macro- and micronutrients, a greater root biomass, deeper root system, and a higher root:shoot ratio, when cultivated on low-fertility soils. We conclude that the enhanced root growth and development by root-specific expression of OsCKX5 could be advantageous for crops grown on oxidic soils in the tropical regions, with a low availability of certain nutrients, especially P and Zn.

Automated summary

Our study showed that root-specific expression of OsCKX5 in rice can enhance root growth, beneficial for crops grown on nutrient-poor soils, and increase the uptake ability of certain macro- and micronutrients.