THP9 enhances seed protein content and nitrogen-use efficiency in maize

Area of Science:

• Plant genetics
• Crop science
• Molecular biology

Background:

• Teosinte possesses significantly higher seed protein than modern maize.
• The genetic basis for this elevated protein content in teosinte remains largely uncharacterized.

Purpose of the Study:

• To identify the genetic factors contributing to high seed protein content in teosinte.
• To investigate the potential of these factors for improving maize nutritional quality.

Main Methods:

• Trio binning for contiguous haplotype DNA sequencing of teosinte.
• Map-based cloning to identify quantitative trait loci (QTLs).
• Analysis of gene expression and transcript splicing in teosinte and maize inbreds.
• Transgenic expression and introgression of candidate genes in maize.

Main Results:

• A major QTL, TEOSINTE HIGH PROTEIN 9 (THP9), was identified on chromosome 9.
• THP9 encodes asparagine synthetase 4, highly expressed in teosinte but affected by a splicing defect in maize B73.
• Transgenic expression of THP9-teosinte increased seed protein in B73 maize.
• Introgression of THP9-teosinte enhanced amino acid accumulation and seed protein in maize without yield reduction.

Conclusions:

• THP9 is a key gene responsible for high seed protein in teosinte.
• THP9 enhances nitrogen-use efficiency and amino acid accumulation in maize.
• THP9 offers a promising target for improving maize nutritional value and sustainable agriculture.