China
June 5, 2026
Maize (Zea mays L.) plays an important role in global food security. During 9,000 years of maize domestication and breeding, however, protein content was not a major breeding target. Consequently, many beneficial gene variants associated with higher protein content were gradually lost from cultivated maize. As a result, modern maize varieties often have low seed protein content, leading to a heavy reliance on imported soybean meal for livestock feed.
Now, Chinese researchers have successfully isolated a key gene from maize's wild ancestor, teosinte, which significantly enhances seed protein content. The gene, Teosinte high protein 3 (THP3-T), was identified and cloned by research teams led by WU Yongrui and WANG Haihai from the Center for Excellence in Molecular Plant Sciences of the Chinese Academy of Sciences, along with WANG Wenqin's team from Shanghai Normal University and Yongcai Huang's team from Sichuan Agricultural University.
Their research was published in Nature on June 3.
In this study, the scientists found that THP3-T encodes glutamate-oxaloacetate transaminase 1 (GOT1), a central enzyme in the nitrogen assimilation pathway. They showed that natural variations in the promoter and coding sequence of THP3-T boost both its expression and enzymatic activity, allowing the plant to use more nitrogen to make proteins. Notably, THP3-T became increasingly rare in most maize lines during domestication, with its frequency in modern maize dropping to only 2.1%.
Furthermore, the researchers demonstrated a powerful synergistic effect when THP3-T was combined with THP9-T, which encodes asparagine synthase 4. By incorporating both superior alleles into Zhengdan958, a widely cultivated elite maize hybrid in China, they achieved a significant increase in seed protein content from 8.5% to 12-13% and whole-plant protein content from 7% to over 9%, all without compromising grain yield.
This study reveals the molecular mechanism behind the decline in maize protein content during domestication. By reintroducing beneficial rare alleles from wild relatives, the researchers have provided a powerful genetic tool for breeding high-protein maize varieties, offering a promising way to meet global food and feed demands. The study marks another breakthrough after the identification of the first high-protein gene, THP9-T.
Reference
Teosinte alleles enhance nitrogen assimilation and seed protein in maize
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