Maternal effect on the inheritance of pericarp colour and grain dimension in rice (Oryza sativa L.)

This study aimed to understand the maternal influence on the inheritance of pericarp colour and grain dimensions in rice, serving as a model for maternal effects in plants. Four crosses, namely Kalarata (red pericarp) x DRR Dhan 58 (white pericarp), DRR Dhan 58 x Kalarata, Kalarata x Pusa 44 (white pericarp), and Pusa 44 x Kalarata, were attempted and their F₁, F₂ and F₃ seeds were analysed. All F₁ seeds of all crosses exhibited the pericarp colour of their corresponding maternal parent, confirming a strong maternal influence. In subsequent generations, F₂ seeds uniformly exhibited red pericarp colour across all crosses, thus reinforcing the influence of maternal genotype on inheritance. However, F₃ seeds were segregated into 9 red: 3 medium red: 4 white, suggesting digenic recessive epistasis (supplementary gene action). Phenotypic assessments indicated nuclear inheritance with maternal effects, while genotypic analysis using gene-based markers revealed polymorphisms at 'Rc' locus and monomorphism at 'Rd' locus, indicating the presence of specific genetic factors in the parental materials used in the study. Additionally, analysis of the grain L/B ratio revealed a similar trend to pericarp colour inheritance, with direct maternal genetic effects in F₁ seeds, consistent uniformity in F₂ seeds and continuous variation in F₃ seeds across all crosses. Welch's test comparisons of L/B ratios suggested a significant maternal impact, particularly in F₃ and F₂ generations, with paternal influence remaining consistent across generations. Deviations in the L/B ratios in certain F₃ segregants suggest environmental influences on grain development. These findings contribute to the understanding of maternal effects in plants and have important implications for rice breeding. The significance of this research lies in its contribution to the relatively unexplored field of maternal effects in plant genetics.