G-string slippage turns white rice red.

Area of Science:

• Plant genetics
• Molecular biology
• Agricultural science

Background:

• The white pericarp phenotype in rice (Oryza sativa subsp. japonica) is controlled by mutations in the regulatory gene, Rc.
• Understanding the genetic basis of pericarp color is crucial for rice breeding and varietal identification.

Purpose of the Study:

• To identify the specific genetic difference responsible for the red pericarp phenotype in the natural red rice mutant 'Perla Rosso' compared to its white pericarp counterpart 'Perla'.
• To elucidate the molecular mechanism underlying the restoration of the Rc gene's reading frame.

Main Methods:

• Comparative genetic analysis of the Rc gene between 'Perla' and 'Perla Rosso' rice cultivars.
• DNA sequencing to identify mutations and assess their impact on gene function.

Main Results:

• A genetic difference was identified within the Rc gene between 'Perla' (white pericarp) and 'Perla Rosso' (red pericarp).
• The red pericarp phenotype in 'Perla Rosso' is associated with the deletion of a single G base within the Rc gene.
• This G base deletion restores the reading frame of the Rc gene, which was disrupted by a previously identified 14 bp deletion in white rice.

Conclusions:

• The identified G base deletion in the Rc gene is the causative mutation for the red pericarp phenotype in 'Perla Rosso' rice.
• This finding provides a precise molecular explanation for the reversion from white to red pericarp in this rice mutant.
• The study highlights the importance of regulatory gene mutations in controlling important agronomic traits like pericarp color.