2026 Volume 76 Issue 4 Pages 341-348
Rice is a staple food for almost half of the world’s population. During domestication from wild rice, the selection of plants with reduced seed shattering enabled efficient harvesting. Further selection for increased grain number improved yield potential. Breeding high-yielding cultivars remains necessary to support the growing world population. Despite success in increasing yield potential, improvements in micronutrient content in rice grains have lagged. Zinc (Zn) is an essential micronutrient for crop productivity and human health. Previously, we reported that reduced seed-setting rate was associated with increased grain Zn concentration, suggesting a trade-off between grain number and Zn concentration. Based on these findings, we investigated the grain Zn concentration in high-yielding rice conferred by Gn1a, a gene involved in the regulation of grain number per panicle. Lower grain Zn concentration was observed in high-yielding plants. However, reducing the seed-setting rate by artificially trimming spikelets at the flowering stage restored grain Zn concentrations in high-yielding plants. Other mineral element concentrations were less affected under high-yielding plants. Our results showed clear trade-off between grain number and Zn concentration, emphasizing the importance of enhancing grain Zn concentrations in breeding programs of high-yielding rice.
