Identifying molecular targets for modulating carotenoid accumulation in rice grains

Area of Science:

• Plant Molecular Biology
• Nutritional Genomics
• Agricultural Science

Background:

• Carotenoids are antioxidants with significant health benefits, including chronic disease protection.
• Dietary supplements are a sustainable way to increase intake of health-benefiting compounds.
• Traditional rice cultivars may offer superior nutritional profiles compared to common varieties.

Purpose of the Study:

• To compare antioxidant compound accumulation in Kavuni and ASD 16 rice varieties.
• To elucidate the molecular mechanisms regulating carotenoid biosynthesis in rice grains.
• To identify genetic targets for enhancing beneficial compounds in rice.

Main Methods:

• RNA-Seq analysis of maturing panicles from Kavuni and ASD 16 rice.
• Comparative transcriptome analysis to identify differentially expressed genes.
• Bioinformatic analysis to map gene expression to metabolic pathways.

Main Results:

• Kavuni rice showed preferential up-regulation of carotenoid precursor and biosynthetic genes (OsDXS, OsGGPS, OsPSY1, OsZ-ISO).
• Enhanced expression of genes (OsLYC-E, OsCYP97A, OsCYP97C) in the alpha-carotenoid pathway led to elevated lutein in Kavuni.
• Differential regulation of positive (Orange, OsDjB7, OsSET29) and negative (AP2, HY5) carotenoid metabolism regulators was observed in Kavuni.

Conclusions:

• Kavuni rice possesses a favorable molecular framework for high carotenoid accumulation.
• Identified gene control points can be targeted for CRISPR-based gene editing to manipulate carotenoid profiles.
• This research paves the way for developing next-generation nutrient-enriched rice, such as 'Golden rice'.