Characterization and bulk segregant analysis of a novel seedless mutant tn-1 of chili pepper (Capsicum annuum)

Seedlessness is a desirable trait to improve eases of processing and fresh consumption of sweet pepper (Capsicum annuum L.). Genetic resources for seedless pepper breeding are limited, compared with other Solanaceae crops. A new seedless mutant named tn-1, was identified by screening an ethylmethane sulfonate mutagenized population derived from ornamental chili pepper. Wild-type fruit contained about 40 seed; tn-1 contained no, or a few seed. Ninety-nine individuals in the F₂ population derived from a cross between tn-1 and other cultivars were classified into the groups: Normal with more than 3 seed in each fruit, and Seedless with less than 3 seed in each fruit. The Seedless group had smaller fruit compared with the Normal group. The average values of fruit weight, length, and width of Normal group were 2.94 g, 3.64 cm and 1.40 cm, respectively. On the other hand, mean values for the Seedless group were 0.64 g, 2.11 cm, and 0.90 cm, respectively. Genetic analysis indicated that seedlessness was determined by a single recessive gene. Bulk segregant analyses combined with genotyping-by-sequencing were conducted to identify the genomic region responsible for seedlessness in tn-1. It appears the gene responsible for seedlessness may be located near the end of chromosome 12. The tn-1 mutant will be a useful breeding material to develop seedless sweet pepper.