Katokkon chili (Capsicum chinense Jacq.) is a unique chili plant belonging to the family of Solanaceae. This chili is one of the site-specific genetic resources found in Tana Toraja and North Toraja Regencies, South Sulawesi Province, Indonesia. The presented research sought to determine the use of different 2,4-D (Dichlorophenoxy acetic acid) concentrations for callus initiation and further in-vitro mutation breeding program, conducted at the Hasanuddin University, Makassar, Indonesia. The chili seeds’ germination occurred in sterile environment, with the hypocotyl part of the sprouts cut and placed on Murashige-Skoog (MS) medium containing 2,4-D concentrations (0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mg L^-1). The experimental layout was a completely randomized design (CRD) with three replications. Results showed 2,4-D concentration 0.5 mg L^-1 had a significant effect on callus weight (24.23 mg), while concentration 1.5 mg L^-1 at the rate of callus appearance and callus formation proportion (6.73 days after culture and 86.7%, respectively). Overall, the callus colors were gray-yellow, yellow-white, orange-white, gray-white, and gray-brown, with friable texture. In addition, the callus was embryonic at concentrations 0.5, 1.0, and 1.5 mg L^-1. The next research plan is to explore the regeneration potential by analyzing somaclonal variation in the regenerated plants.

Keywords: Katokkon chili (Capsicum chinense), peppers, 2,4-D concentrations, callus, in-vitro mutation breeding

Key findings: In Katokkon chili (Capsicum chinense) plants, the tissue culture technology for using 2,4-D to stimulate callus formation originating from the chili hypocotyl is unknown. The presented study determined the most effective 2,4-D concentration to induce callus in chili katokkon hypocotyl derived from sterile sprouts for further in-vitro mutation breeding programs.