Genetic mapping of simply inherited categorical traits, including anthocyanin accumulation profiles and fruit appearance, in eggplant (Solanum melongena)

Abstract

Background: The appearance quality of the eggplant (Solanum melongena L.) fruit is an important trait that influences its commercial value. It is known that quality traits such as anthocyanin composition and fruit surface pattern are categorical and are inherited simply. However, research examples of gene mapping for the composition (anthocyanin accumulation profile) and the surface pattern in eggplant fruit are limited.

Methods and results: To map loci for these traits including the accumulation profiles of two anthocyanins, a widely spreading anthocyanin, delphinidin 3-(p-coumaroyl) rutinoside-5-glucoside (nasunin), and the relatively rare delphinidin 3-glucoside (D3G), we used two F₂ intracrossed populations (LWF2 and N28F2). For the LWF2 population, mapping was achieved by reconstructing the linkage map created by Fukuoka et al. [1]. In the case of the N28F2 population, we constructed a linkage map consisting of 13 linkage groups using 238 simple sequence repeats, 75 single-nucleotide polymorphisms. Using the two F₂ populations, the nasunin accumulating profile, the striped pattern on the fruit surface, the colors of flowers, fruit, and calyxes, and the D3G accumulating profile were genetically mapped. Furthermore, by utilizing the eggplant reference genome information, mutations in the causative candidate genes for those loci were identified.

Conclusion: Overall, the results of this study suggest that inactivation of key enzymes of anthocyanin metabolism and the gene orthologous to the tomato u gene are potential causes of observed variety in eggplant appearance traits.

Keywords: Anthocyanin; Appearance quality; Categorical trait; Eggplant (Solanum melongena); Genetic mapping.