Induction and characterization of a novel high-protein mutant in peanut (Arachis Hypogaea L.)

Abstract Peanut, a globally significant food crop, is highly valued for its nutritional and economic importance. However, breeding efforts to enhance its protein content have been limited. In this study, a two-step chemical mutagenesis strategy was utilized on the normal-protein Spanish-type peanut cultivar Fuhua 19 (< 25% protein) to generate high-protein mutants. Through successive rounds of mutagenesis combined with near-infrared spectroscopy screening, eight mutants with protein levels exceeding 30% were identified. Among these, the mutant C-Za-454-2 consistently exhibited stable and elevated protein content across different locations and developmental stages. This mutant also displayed distinct ultrastructural changes, including an increased protein body area and reduced starch grain content, compared to the wild-type Fuhua 19. Biochemical analyses revealed enhanced activities of nitrogen metabolism enzymes, such as nitrate reductase and glutamate synthetase, which positively correlated with protein accumulation. Conversely, certain carbon metabolism enzyme activities were inversely correlated with protein content, highlighting a trade-off between carbohydrate and protein synthesis. These findings demonstrate the efficacy of iterative mutagenesis in producing high-protein peanut lines and provide a foundation for future genetic studies aimed at improving protein yield in peanut cultivars.