Variations in CYP78A13 coding region influence grain size and yield in rice

Area of Science:

• Plant genetics
• Crop science
• Molecular biology

Background:

• Grain size is a critical factor determining crop yield in cereals.
• Understanding the genetic basis of grain size is essential for agricultural improvement.

Purpose of the Study:

• To identify genes controlling grain size in rice.
• To investigate the role of OsCYP78A13 in regulating rice grain development and yield.

Main Methods:

• Utilized enhancer-trapping mutagenesis to identify mutants affecting grain size.
• Employed genetic analysis and SiteFinding PCR to identify the causative gene.
• Conducted sequence polymorphism analysis and created transgenic plants to validate gene function.

Main Results:

• Identified the big grain2 (bg2-D) mutant, caused by a dominant mutation in OsCYP78A13, which encodes a cytochrome P450.
• Demonstrated that both OsCYP78A13 and its paralogue GL3.2 promote grain growth.
• Found significantly higher nucleotide diversity in OsCYP78A13 within indica rice varieties compared to japonica varieties.
• Determined that variations in the OsCYP78A13 coding region are linked to variations in grain yield.

Conclusions:

• OsCYP78A13 is a key regulator of rice grain size and yield.
• Genetic variations in OsCYP78A13, especially within indica rice, present valuable opportunities for enhancing rice breeding programs aimed at increasing grain yield.