Release Subtitle:
Researchers uncover how a magnesium transporter controls rice grain development, nutritional quality, and cooked rice texture
Release Summary Text:
Magnesium is essential for both plant growth and human nutrition, yet how rice grains accumulate this mineral has remained unclear. A new study identifies OsMGR2 as a magnesium transporter required for moving magnesium into rice grains. Rice plants lacking this transporter produced smaller, shriveled grains with reduced magnesium content and poorer eating quality. The findings reveal how magnesium distribution affects grain development and could help support future breeding strategies for nutritionally improved rice varieties.
Full text of release:
Rice is a staple food for nearly half of the global population and an important dietary source of magnesium, a mineral essential for human health, plant growth, and energy metabolism. Although magnesium is known to influence grain quality and taste, the biological mechanism controlling how the mineral reaches rice grains has remained largely unknown. Understanding this pathway has become increasingly important as scientists seek ways to improve both crop nutrition and resilience under nutrient-limited conditions.
Addressing this challenge, a research team led by Professor Jian Feng Ma at the Institute of Plant Science and Resources, Okayama University, Japan, along with Dr. Sheng Huang from the same institute, and Dr. Kiyosumi Hori from the National Institute of Crop Science, National Agriculture Research Organization, Japan, investigated how magnesium is transported inside rice plants and eventually delivered into grains. The researchers focused on a previously uncharacterized transporter protein called OsMGR2, which belongs to the Magnesium Release transporter family. Their findings were made available online on April 22, 2026, and were published in Volume 123 Issue 17 of the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS) on April 28, 2026.
Using gene expression analysis, isotope tracing, imaging, transport assays, and CRISPR/Cas9-generated mutant rice plants, the team demonstrated that OsMGR2 functions as a magnesium efflux transporter located in the plasma membrane. The transporter was highly expressed in vascular tissues responsible for nutrient distribution throughout the plant. When the researchers disabled the OsMGR2 gene, magnesium accumulated abnormally in roots and husks instead of being efficiently delivered to shoots and grains.
The mutants displayed severe growth defects under low-magnesium conditions, including leaf chlorosis, reduced biomass, and poor grain development. Their rice grains were smaller, lighter, shriveled, and less transparent compared with normal rice plants. The team also discovered that cooked rice from the mutant plants had significantly lower eating quality scores, with reduced stickiness and altered texture. These findings revealed that magnesium transport is closely linked not only to crop productivity but also to sensory traits valued by consumers.
Prof. Ma explained the motivation behind the work: “Rice is one of our major dietary sources of magnesium, yet the mechanism of magnesium accumulation in grains was unknown. We wanted to uncover how this important nutrient reaches the grain.” The researchers further found that OsMGR2 helps direct magnesium toward actively growing tissues and developing grains, ensuring proper starch synthesis and grain filling during maturation.
The discovery may open new opportunities for agricultural innovation. Magnesium deficiency in soils is becoming a growing concern in several rice-producing regions, reducing yields and grain quality. By understanding the molecular basis of magnesium transport, breeders may eventually develop rice varieties that tolerate magnesium-poor environments while maintaining nutritional value and eating quality. “Our findings provide a foundation for improving both grain nutrition and rice quality through future breeding programs,” Prof. Ma noted.
Overall, the study highlights how a single transporter can coordinate nutrient allocation, seed development, and food quality in one of the world’s most important crops. Beyond rice, the findings may also inspire broader research into mineral transport systems in cereals and other staple foods, potentially supporting future strategies for global nutritional security.
Reference:
Title of original paper: A magnesium efflux transporter required for seed development and eating quality in rice
Journal: Proceedings of the National Academy of Sciences of the United States of America (PNAS)
DOI: 10.1073/pnas.2536813123
Contact information
Contact Person: About Professor Jian Feng Ma from Okayama University, Japan
Prof. Jian Feng Ma is a Full Professor and Director at the Institute of Plant Science and Resources, Okayama University, Japan. He earned his Ph.D. in plant nutrition from Kyoto University in 1991 and later conducted postdoctoral research at the Suntory Institute for Bioorganic Research. His research focuses on mineral transporters and aluminum stress tolerance mechanisms in plants, particularly rice and barley. He has published over 340 papers in leading journals, including Nature and PNAS. Recognized globally, he has received prestigious honors such as the JSPS Prize, Japan Academy Medal, National Medal with Purple Ribbon, and Frontier Planet Prize in 2023.