Natural variation in the CONSTANS-like gene TaCOL1-7D modulates root growth and nitrogen uptake in wheat

The root system is essential for plant development and nutrient acquisition; however, the genetic and molecular mechanisms governing root elongation and function in wheat remain largely unknown. In this study, we identified a novel quantitative trait locus (QTL), QRL.cau-7D, associated with root elongation in wheat. Through map-based cloning, we identified TaCOL1-7D, a CONSTANS-like (COL) transcription factor, as the causal gene underlying this QTL. Functional analyses revealed that TaCOL1-7D promotes root elongation through modulation of lignin biosynthesis and by physical interaction with TaMADS25, a regulator of root architecture and nitrogen uptake. Furthermore, our findings suggest that TaCOL1-7D participates in nitrogen absorption by increasing the transcription factor activity of TaMADS25. An elite allelic variant, TaCOL1-7D^TAA10, was found to promote both root elongation and nitrogen absorption. This study provides new insights into the genetic basis of root system architecture in wheat and opens avenues for improving nutrient uptake efficiency through molecular breeding.