Mechanisms Behind Maize's Low Seed Protein Content Uncovered

By crossing maize with a wild ancestor that has three times the seed protein content of most modern strains of the crop plant, a team led by scientists from the Chinese Academy of Sciences has uncovered the mechanisms behind this protein loss. Teosinte comprises a group of wild grasses that were cultivated to give rise to maize. Over the course of this process, the plant's seed protein levels were reduced, but exactly how this occurred has not been clear. As they report in Nature this week, the researchers crossed teosinte with maize and analyzed the progeny, identifying a major high-protein quantitative trait locus — dubbed THP9 — on chromosome 9. THP9 encodes an asparagine synthetase 4 enzyme that is highly expressed in teosinte, but not in a maize inbred line. Expressing THP9 in the inbred line, however, significantly increased its seed protein content without affecting the plant's yield. The findings, the study's authors write, could aid in the improvement of maize