Rapeseed transcription factor BnaC9bHLH35 promotes root growth and improves nitrogen use efficiency under low nitrate...

Area of Science:

• Plant Molecular Biology
• Agricultural Science
• Genetics

Background:

• Nitrogen is essential for plant growth, forming proteins and nucleic acids.
• Improving crop nitrogen use efficiency (NUE) is crucial for sustainable agriculture and reducing fertilizer input.
• Low nitrate conditions pose a significant challenge to crop productivity.

Purpose of the Study:

• To identify and characterize transcription factors involved in rapeseed's low nitrate response.
• To elucidate the regulatory role of BnaC9bHLH35 in nitrate uptake and assimilation.
• To evaluate the potential of BnaC9bHLH35 for improving crop NUE.

Main Methods:

• Identification of BnaC9bHLH35 under low nitrate stress.
• Analysis of BnaC9bHLH35 localization and gene expression.
• Overexpression studies in *Arabidopsis thaliana* to assess root development.
• Chromatin immunoprecipitation followed by quantitative PCR (ChIP-qPCR) to confirm direct gene binding.

Main Results:

• BnaC9bHLH35 is a transcription factor induced by low nitrate stress with unique multiple localization.
• It enhances expression of nitrate uptake genes (BnaNRT) and nitrate reductase (BnaNR), while downregulating BnaCLCB.
• Overexpression of BnaC9bHLH35 promoted root elongation and lateral root density in low nitrate conditions.
• ChIP-qPCR confirmed direct binding of BnaC9bHLH35 to target gene promoter regions.

Conclusions:

• BnaC9bHLH35 is a key regulator of rapeseed's response to low nitrate availability.
• This transcription factor directly controls genes involved in nitrate uptake and assimilation, thereby improving NUE.
• BnaC9bHLH35 holds potential for genetic engineering strategies to enhance NUE in rapeseed varieties.