Ancient corn breeders accidentally rewired a gene that fills the ears
Guo L, Xia J, Tang J, Zhang M, Chen T
Crop Improvement
The sweet corn or dent corn you grow owes its fat, well-filled ears to a tiny DNA switch that wild teosinte, corn's scraggly ancestor, never had.
Corn's wild ancestor put most of its energy into leaves and stalks, leaving skinny, sparse ears. Early farmers unknowingly selected a small DNA insertion that acts like a volume knob, turning up a gene that tells the plant to send more sugar and nitrogen into the kernels instead. Researchers traced exactly how this switch works at the molecular level, and it still boosts yield even when nitrogen fertilizer is scarce, which could help breed better corn with less fertilizer.
Key Findings
Maize harvest index increased by 81% during domestication from its wild ancestor teosinte.
A 9.1-kb DNA insertion (HI1) acts as a distant enhancer that boosts expression of the BRR1 gene by forming a chromatin loop with help from transcription factor CONZ1 and acetyltransferase GCN5.
BRR1 activates carbon and nitrogen transport genes, improving grain yield and harvest index even under nitrogen-limited conditions.
chevron_right Technical Summary
Scientists found a small genetic switch that ancient farmers unknowingly selected in corn, one that redirects the plant's sugar and nitrogen toward the ears instead of the leaves and stalk, boosting grain yield by over 80% since domestication.
Abstract Preview
Original paper
A domestication-selected enhancer coordinates source-sink balance to improve harvest index and yield in maize.
Crop yield is fundamentally determined by the harvest index, the proportion of photosynthates allocated to grain. However, its genetic and evolutionary basis remains elusive. Here, we show that the...
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Zea is a genus of flowering plants in the grass family. The best-known species is Z. mays, one of the most important crops for human societies throughout much of the world. The four wild species are commonly known as teosintes and are native to Mesoamerica.