Researchers Analyze Rice QTL for Grain Size and Yield

Grain weight is the most important component of rice yield and is determined by grain size, which is then controlled by quantitative trait loci (QTLs). Although numerous QTLs that regulate grain weight have been identified, the genetic network that controls grain size remains unclear.

Researchers, led by Shuangcheng Li of the Sichuan Agricultural University, report the cloning and functional analysis of a dominant QTL, grain length and width 2 (GLW2), which positively regulates grain weight by increasing grain length and width.

Analysis found that GLW2 locus encodes OsGRF4 (growth-regulating factor 4) and is regulated by the microRNA OsmiR396c. A mutation in OsGRF4 disturbs OsmiR396's regulation of OsGRF4, resulting in larger grains and enhanced grain yield. The team also found that OsGIF1 (GRF-interacting factors 1) directly interacts with OsGRF4, and increasing its expression also improves grain size.

The results suggest that the miR396c-OsGRF4-OsGIF1 interaction plays an important role in grain size determination and yield improvement.

For more on this promising study, read the article in Plant Biotechnology Journal.