Genetic mapping and functional characterization of two recessive loci governing white testa color in peanut (Arachis hypogaea L.)

Peanut is a globally significant oil crop and economic resource, notable for its kernel containing over 50% oil content. White testa peanuts are highly valued for their superior nutritional profile, minimal pigmentation, and superior oil clarity. Identification of genes controlling white testa color is crucial for advancing breeding programs and understanding the genetic mechanisms involved. A genetic mapping study was performed in peanut to identify genes controlling white testa color, a trait associated with desirable end-use quality traits in this oilseed crop. In an F₂ population generated from a cross of a white-testa with a pink-testa cultivar, two recessive quantitative-trait loci controlling white testa were identified and fine-mapped to A02 and B02 chromosomes. Two homologous genes, Arahy.MP3D3D and Arahy.26781N, encoding bHLH transcriptional factors, were identified as candidates for the two loci. Reduced expression of these two genes likely suppresses anthocyanin biosynthesis.