COMPARATIVE EXPRESSION OF ANTHOCYANIN-RELATED GENES, PIGMENT ACCUMULATION, AND GRAIN QUALITY TRAITS IN A BLACKKERNEL MUTANT AND WILD-TYPE INDICA RICE (Oryza sativa L.)

Abstract

Pigmented rice is a rich dietary source of anthocyanins and flavonoids with potential health benefits, with limited yield and quality trade-offs. However, the relationship between pigment accumulation, agronomic performance, and grain quality remains poorly defined. In this study, we conducted a comparative analysis of a gamma-ray-induced black-kernel rice mutant (9311 bk) and its wild-type progenitor (9311). Agronomic, physiological, and biochemical traits were evaluated under field conditions. The mutant exhibited taller plants and longer grains, but had a reduced seed-setting rate and 1000-grain weight. Quality assessment revealed significantly greater grain length and width but reduced brown rice recovery rate and amylose content in the mutant compared to the wildtype. Biochemical assays revealed significantly higher anthocyanidin, flavonoid, and polyphenol accumulation in 9311 bk grains, coinciding with strong upregulation of seven key anthocyanin biosynthetic genes (PAL, CHS, CHI, F3H, F3’H, DFR, ANS). Thermal profiling indicated an altered starch structure in the mutant. At the same time, correlation analyses showed strong positive relationships between anthocyanidin levels and gene expression, but negative correlations with starch, sucrose, and grain weight. Our findings demonstrate that while pigment-rich rice confers enhanced nutritional and functional food benefits, its induction through mutagenesis may introduce trade-offs affecting grain yield and processing quality. These insights highlight the need for balanced breeding strategies that integrate pigment biosynthesis with yield stability and grain quality traits. Practically, this study provides a framework for developing improved pigmented rice cultivars with optimized anthocyanin content, better nutritional value, and acceptable agronomic performance suitable for both health-oriented and commercial rice production systems