Overexpression of zmm28 increases maize grain yield in the field (PNAS)

This study, from scientists at Corteva Agriscience, demonstrates a yield boost in transgenic maize overexpressing a gene encoding a transcription factor. Expression of zmm28, a maize MADS-box transcription factor gene, is elevated through fusion to a maize GOS2 promoter, which provides moderate, constitutive expression in all cell types (GOS2 encodes a translation-initiation factor). The authors demonstrate increased yields in numerous field trials: “Over this 4-y period, a total of 48 hybrids ranging in relative maturity from 105 to 113 d were evaluated at 58 locations,” with the zmm28-expressing plants showing a consistently higher yield. Transgenic plants were also larger with more leaf biomass and increased rates of photosynthesis, as well as increased nitrogen uptake assimilation. Transcriptomic analysis as well as ChIP-Seq and yeast one-hybrid analsis identified direct targets of ZMM28, including genes involved in photosynthesis and hormone production and response. The authors conclude that, “alteration in expression of a single native gene in maize, zmm28, can improve both resource capture and resource utilization, resulting in a significant improvement in grain yield, the ultimate complex quantitative trait.” (Summary by Mary Williams) Proc. Natl. Acad. Sci. USA