In vitro regeneration and optimization of physical and chemical mutagenesis protocol in tuberose (Agave amica (Medik.) Thiede & Govaerts) cv. 'Arka Vaibhav'.

Purpose: Tuberose (Agave amica [Medik.]) is a vegetatively propagated commercial flower crop with limited genetic variability. Crossing barriers prevailing in tuberose necessitates modern breeding techniques like in vitro mutagenesis to generate variability. Hence, this study aimed to establish an efficient in vitro regeneration protocol for the rapid multiplication of tuberose and optimize the method for in vitro mutagenesis using the terminal stem scale as the explant.

Results: MS medium supplemented with 17.74 µM benzyl aminopurine) (BAP) and 0.57 µM indole-3-acetic acid (IAA) showed the maximum number of multiple shoots (5.0), with optimal shoot length (6.77 cm) and number of leaves (6.07). The shoots formed maximum rooting (99.44%) in MS medium supplemented with 4.90 µM indole-3-butyric acid, with an average of 26.89 roots per shoot. In vitro mutagenesis attempted physically via gamma irradiation led to an LD_{25, 50, 75} values of 13.21, 20.81, 32.79 Gy, respectively. The incorporation of ethyl methane sulfonate (EMS) into the culture media at a concentration of 0.08%, 0.13%, and 0.21% effectively resulted in LD_{25, 50, 75}, respectively. Pretreating explants with 0.13% EMS for 15 min, 0.18% EMS for 30 min, 0.14% EMS for 45, and 0.11% EMS for 60 min were optimal for achieving 50% survival and plant regeneration using the regeneration protocol described above.

Conclusion: The regeneration protocol and optimized mutagen dose for in vitro mutagenesis developed in this study can be utilized for rapid multiplication of the cultivar and as a tool in genetic improvement programs aimed at inducing variability for commercially significant traits in tuberose.