Genetic analysis of fruit quality traits in prebred lines of watermelon derived from a wild accession of Citrullus amarus

Abstract

Citron (Citrullus amarus) is a watermelon (Citrullus lanatus) relative that is reported to carry disease resistance alleles to several important pathogens. It is therefore important to understand the inheritance of fruit quality traits while using this species to introgress resistance traits. Hence, the current experiment was carried out to determine the inheritance of important external and internal fruit quality traits in prebred lines derived from C. amarus and confirm the role of candidate genes for quality traits in these genotypes. The study comprised of two backcross inbred lines viz, BIL-53 and BIL-99 as female parents crossed to IIHR-140-152, an icebox type elite inbred line as a common pollen parent for developing F1, F2, BC1 and BC2 generations to study genetics of fruit shape, flesh color, rind pattern, total soluble solids (TSS), and seed color. Results suggested that the genetics of most of these fruit quality traits are governed by one or two genes suggesting simple inheritance. Sequencing of candidate gene, Cla011257 confirmed its involvement for fruit shape in this species and also revealed a novel allele with two SNPs resulting in oblong fruit shape. Similarly, the flesh color candidate gene, LCYB was involved in variation between canary yellow and red flesh colors but was found to be not involved in salmon yellow color observed in progenies derived from this species. Overall, our results suggest that breeders can use C. amarus as a source of resistance in breeding programs without linkage drag of alleles detrimental for fruit quality traits.