Chinese Scientists Map Rice Growth

• Researchers created a 3D map covering rice development from seed to mature plant.

• The study found different gene-activity patterns linked to starch and protein accumulation in developing grains.

• The findings could help scientists pursue more targeted approaches to improving rice quality.

Chinese scientists have developed a detailed three-dimensional map of rice development that could provide new clues for improving the quality, nutritional characteristics and other traits of one of the world's most important food crops.

The study, published online in the international journal Cell, brings together spatial transcriptomics, single-nucleus RNA sequencing and a gap-free reference genome to track rice development from seed germination through flowering and grain formation.

Researchers from the Yazhou Bay National Laboratory, BGI-Research, Southern University of Science and Technology, Huazhong Agricultural University, Wuhan University and other institutions collaborated on the project.

Using the japonica rice variety Zhonghua 11, the team constructed a spatiotemporal atlas covering 10 major organs and 61 developmental stages. The research analysed more than 851,000 cell nuclei and more than 347,000 spatial measurement areas, identifying 119 cell types and 133 cell subtypes across the rice lifecycle.

The result provides scientists with a detailed view of not only which genes are active during rice development, but also where those genes are active and when their activity changes.

This spatial information is particularly important when studying the rice grain.

Rice grains are largely made up of the endosperm, the tissue that stores nutrients for the developing embryo and forms most of the edible portion of the grain. Researchers found that the developing endosperm is not genetically uniform, with different regions showing different gene-expression programmes.

Genes associated with carbohydrate metabolism and starch synthesis were more strongly concentrated toward the dorsal side of the developing endosperm, while genes associated with storage-protein production were more prominent toward the ventral side.

The researchers also found that altering genes involved in these regional programmes could change the distribution patterns of starch and protein within the developing grain.

The findings offer a new way of looking at rice quality. Instead of examining a grain only as a whole, scientists can investigate how different areas develop and how local gene activity contributes to the final composition of the grain.

Researchers said the discovery could open new avenues for studying grain filling, nutrient distribution and quality formation, potentially helping breeders pursue more targeted strategies for improving rice varieties.

Another finding involved OsARF1, a regulatory factor that appears to perform different functions depending on the cellular environment in which it operates. The research suggests that the effects of such regulators can depend on their specific spatial and developmental context.

That could be important for crop improvement because changing a major regulatory gene can sometimes affect several traits.