Seedling-derived split internode and leaf explants as efficient alternatives for callus induction in tropical maize

Abstract

The development of effective callogenesis and regeneration protocols remains a major challenge for tropical maize genotypes, which are often recalcitrant to in vitro culture techniques. This study aimed to evaluate the callogenic potential of seedling-derived split internodes and leaf explants in four local maize varieties. Explants were cultured on five auxin-cytokinin induction media. Callus induction percentage and relative fresh weight growth rate (RFWGR) were measured. Data were analyzed using two-way ANOVA followed by Duncan’s Multiple Range Test (α = 0.05). Callus induction and proliferation were strongly genotype-dependent. Split internodes consistently produced higher RFWGR than leaf explants. Media containing 2-2.5 mg/L 2,4-D combined with BAP or kinetin (M1-M3) yielded the highest responses, particularly in variety CHABA. Seedling-derived explants represent efficient alternatives to immature embryos for tropical maize callogenesis. The identified genotype-explant-medium combinations provide a basis for developing regeneration and transformation protocols adapted to tropical germplasm. This study does not involve human participants or clinical trials.