Investigation of 2-Aminopurine Effect on Mutation Induction in Hoya Hearts (Hoya kerrii)

Hoya hearts (Hoya kerrii) is a decorative plant with beautiful leaf shapes and long-lasting flowers. Creation of new clones of this plant through in vitro mutagenesis has potential for genetic diversity and economic development. Aim: This study aims to investigate the impact of 2-Aminopurine (2-AP) on mutation induction in Hoya kerrii and assess its effects through morphological, anatomical, and molecular evaluations. Materials and Methods: In vitro-cultured segments of Hoya kerrii stems were treated in 2-AP solutions of 0%; 0.15%; 0.25%; 0.35%; 0.45% concentrations for 1 hour before culturing into a shoot regeneration medium. Regenerated shoots were subcultured in root formation medium before acclimatisation. An anatomical analysis of leaf petioles and genotypic variation of mutant plants was carried out using double-dyeing with Carmin vert d’iode and RAPD and ISSR markers. The highest shoot regeneration rate (100%) was observed in the control and 0.15% 2-AP treatments, while the lowest was at 0.45% 2-AP (81%). In vitro root formation using 0.25% 2-AP achieved the greatest root quantity and length, while 0.35% had the lowest. The 0.25% 2-AP treatment also resulted in the highest acclimatisation rate of 98.41%, alongside noticeable floral changes, such as distinct petal morphology and pistil colouration. Result: An anatomical analysis of leaf petioles showed that increasing the concentration of 2-AP increased petiole diameter, epidermal thickness, and vascular tissue area. Genotypic analysis using RAPD and ISSR markers indicated that the 0.25% 2-AP sample showed the greatest genetic divergence compared to the wild type. Major Findings: These findings suggest that the 0.25% 2-AP concentration is optimal for inducing stable mutations in Hoya hearts, enhancing both phenotypic traits and genetic diversity for ornamental breeding.