On the 8th, the internationally renowned journal Science published the latest achievement from the research team led by Dr. Tong Hongning, a researcher at the Crop Science Institute of the Chinese Academy of Agricultural Sciences. This breakthrough unravels the genetic code behind the formation of complex rice grains, a mystery that has puzzled the international community for nearly a century. The study reveals the intricate role of plant hormones, brassinosteroids, in regulating the number of grains in rice panicles, laying a theoretical foundation and forging a new path for breeding high-yielding rice varieties.
The photo source: Crop Science Research Institute, Chinese Academy of Agricultural Sciences.
Complex-grain rice is a type of rice germplasm characterized by the trait of multiple grains clustered together. Since the 1930s, the genetic mechanism behind complex-grain rice has remained a mystery. According to the lead author Tong Hongning, the research team spent seven years creating 10,000 mutagenic strains (approximately 160,000 individual plants) of complex-grain rice, ultimately identifying two non-clustered mutant strains, thus pinpointing the mutated gene. Further analysis revealed, for the first time, that brassinosteroids regulate the secondary branching of rice panicles, controlling the number of grains per panicle.
Field trials showed that compared to the non-clustered controls, one strain of complex-grain rice developed by the research team had 35.2% more secondary branch stems, resulting in a 28.2% increase in grain number per panicle. This discovery challenges the conventional understanding of the trade-off between grain number and weight in rice, offering possibilities for the improvement of new rice varieties and achieving breakthroughs in yield.
"This research finding that brassinosteroid content controls certain specific traits of complex-grain rice indicates that exploring genetic resources from germplasm is an effective approach to overcoming current crop yield bottlenecks," said Lin Hongxuan, academician of the Chinese Academy of Sciences.
