Genetic Characterisation of Anthocyanin Accumulation in Diverse Rice Germplasm

Abstract

Anthocyanins are natural pigments found in various crops, including rice, such as black rice. They enhance food quality and help fight oxidative stress, inflammation, and chronic diseases. New black rice genotypes have been introduced into Uganda, however, the genetic analysis of anthocyanin content among them is unknown, which complicates efforts to improve anthocyanin levels in Ugandan rice germplasm. Thus, this study. aimed to determine the gene action, heritability and combining ability for anthocyanin content in black rice genotypes. The study was carried out on black rice genotypes (BR-11, BR-12, BR-14 and BR-15) and commercial white rice varieties (NR-1, NR-2, NR-3, NR-4 and OKILE) crossed using the North Carolina II mating design. The F2 seeds were evaluated for anthocyanin content using the pH-diferential method, and data were analysed using Gen Stat of the 23rd edition. The study revealed signifcant diferences in general combining ability (GCA) and specifc combining ability (SCA) mean squares, indicating the importance of additive and nonadditive gene action in controlling the trait under investigation. The GCA and SCA variance components revealed a very high broad-sense heritability (>0.9), indicating the predominance of the genotype over the environment effect, a high narrow-sense heritability (>0.5), and a Baker’s ratio (>0.5), indicating the predominance of additive in heritance among crosses evaluated in Namulonge at the National Crops Resources Research Institute (NaCRRI), thus anthocyanin content being controlled by an additive type of gene action. Maternal effects were suspected to be presenting anthocyanin content, refected by a higher female GCA variance than male GCA variance. Genotypes BR-11 and BR-12 were good combiners and could be used as donors in improving rice for anthocyanin content by plant breeders. Crosses NR-2/BR-11, NR-3/BR-11, OKILE/BR-11, NR-2/BR12, NR-3/BR-12, NR-4/BR-12, NR1/BR-14, NR1/BR-15 and NR-4/BR-15 were recorded as the best performers for anthocyanin content as they had a high positive SCA, a higher mean, and at least one of the parents had a good GCA for anthocyanin content. Therefore, advancing them and the selections made during early generations is necessary. This study recommends further evaluation of studied materials across different agro-ecologies for several seasons in Uganda to know the stability, adaptability and generate conclusive results on the type of gene action controlling anthocyanin content. It also recommends the need to evaluate reciprocal crosses to have conclusive results on the maternal inheritance of anthocyanin content.