Low-nitrogen-inducible gene expression cassettes for improving nitrogen use efficiency in crops

Overview

This research program focuses on developing genetically modified crops with improved nitrogen use efficiency (NUE) through the application of artificial expression cassettes. These cassettes combine nitrogen transporter (NRT) and ammonium transporter (AMT) genes with low-nitrogen-inducible enhancers and promoters, enabling crops to activate nitrogen uptake mechanisms precisely when nitrogen availability is limited. The goal is to reduce dependence on nitrogen fertilizers while maintaining crop yields, supporting both economic and environmental sustainability in agriculture.

Technical specifications

Core approach:

• Artificial expression cassettes containing NRT and AMT genes driven by low-N-inducible regulatory elements
• Genome-wide profiling of open chromatin regions using DNase-seq and MH-seq under control and low-nitrogen conditions
• RNA-seq analysis of time-course leaf tissue samples to identify nitrogen-responsive gene expression patterns
• Identification of differentially expressed genes and nitrogen-inducible DHSs (DNase I hypersensitive sites) or MHSs (MNase hypersensitive sites) across rice, maize, and millet genomes
• Construction and testing of transgenic lines containing optimized expression cassettes

Target crops: Rice, maize, and millet

Key applications:

• Crop breeding for improved nitrogen translocation and utilization
• Reduced nitrogen fertilizer requirements in agricultural production
• Maintenance of crop yields under nitrogen-limiting field conditions
• Environmental protection through decreased fertilizer runoff

Technology readiness level

The research is currently in the discovery and validation phase. Low-nitrogen-inducible promoter and enhancer candidates have been identified through RNA-seq analysis of rice leaf tissues under control and low-nitrogen treatments. Stress-inducible candidates have also been obtained from maize, rice, and millet using DNase-seq and MH-seq approaches. Future validation steps include genome-wide chromatin profiling under low-nitrogen conditions, identification of nitrogen-inducible regulatory elements, construction of artificial expression cassettes, generation of transgenic lines, and selection of optimal lines for further propagation. The technology is at an early-to-mid stage of development, with proof-of-concept validation in transgenic plants still required before commercial application.