For decades, rice breeders have confronted a persistent challenge: increases in grain yield are often accompanied by declines in grain quality. This long-standing trade-off has substantially impeded the development of rice varieties that simultaneously achieve high yield and superior quality.
Using chromosome segment substitution lines derived from elite rice cultivars, researchers identified a key gene, GSN7 , located on chromosome 7. The study demonstrated that loss-of-function mutations in GSN7 result in longer and slimmer grains with higher translucency and reduced chalkiness, while markedly increasing the number of grains per panicle. Notably, the thousand-grain weight remains unchanged, thereby leading to significant improvements in both yield and quality.
At the molecular level, GSN7 interacts with OsGSK2, a central kinase involved in grain development, and competes with the known inhibitor GW5 for binding. Through this competitive interaction, GSN7 modulates OsGSK2 activity, thereby finely regulating grain morphology.
An analysis of diverse rice germplasm revealed that a specific natural haplotype of GSN7, designated Hap.3, is strongly associated with superior grain shape and high yield. However, this favorable haplotype has not been widely exploited in modern breeding programs. Its identification, therefore, provides a valuable target for marker-assisted selection, facilitating the rapid introgression of elite traits into high-performing cultivars.
Overall, the study demonstrates that precise manipulation of GSN7 —via gene editing or marker-assisted selection—can overcome the long-standing yield–quality trade-off.
This work was conducted by a research team from the State Key Laboratory of Seed Innovation at the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, a leading institution in plant genetics and crop improvement dedicated to advancing sustainable agriculture through cutting-edge research.
Science Bulletin