MeNPF4.5 Improves Cassava Nitrogen Use Efficiency and Yield by Regulating Nitrogen Uptake and Allocation.

Area of Science:

• Plant Biology
• Agricultural Science
• Biochemistry

Background:

• Improving nitrogen use efficiency (NUE) is critical for global crop production.
• Cassava primarily utilizes nitrate as its nitrogen source.
• Understanding nitrate transporters is key to enhancing crop NUE.

Purpose of the Study:

• To evaluate the role of the nitrate transporter gene *MeNPF4.5* in cassava's nitrogen uptake and utilization.
• To assess the impact of *MeNPF4.5* gene expression levels on cassava growth and yield.

Main Methods:

• Generated *MeNPF4.5* overexpression (OE) and RNA interference (RNAi) lines in cassava.
• Conducted tissue culture and field trials under varying nitrogen conditions.
• Analyzed plant growth, yield, nitrogen content, photosynthesis, enzyme activities, and hormone levels.

Main Results:

• *MeNPF4.5* is a root-expressed, nitrate-inducible plasma membrane transporter.
• OE lines showed improved growth, yield, and NUE, especially under normal nitrogen.
• RNAi lines exhibited reduced growth and nitrogen uptake, despite increased certain enzyme activities.
• OE lines had higher photosynthesis and N-metabolism enzyme activity; RNAi lines showed decreased photosynthesis.
• Hormone (IAA) levels were altered in OE and RNAi lines, correlating with NUE.

Conclusions:

• *MeNPF4.5* plays a significant role in regulating nitrogen uptake and utilization in cassava.
• This transporter influences NUE by modulating N-metabolizing enzyme activity, photosynthesis, and hormone levels.
• *MeNPF4.5* is a promising target for breeding cassava with enhanced nitrogen use efficiency and yield.