Regeneration of transgenic taro ( Colocasia esculenta var. esculenta) via microprojectile bombardment of embryogenic cell suspensions

This study outlines the development of a gene delivery system for taro ( Colocasia esculenta var. esculenta ) using biolistic transformation. The binary vector pART-TEST7, carrying the green fluorescent protein (gfp) reporter and the neomycin phosphotransferase II (nptII) selectable marker genes, was introduced into embryogenic suspension cultures of genotypes CPUK and THA-07. Cells were bombarded with gold particles at 550 kPa helium pressure under -85 kPa vacuum, positioned 7.5 cm from the microprojectile launch point. Green fluorescence was visible within 72 hours, indicating transient gfp expression. Notably, placing the cells in an osmotic medium (0.2 M mannitol and 0.2 M sorbitol) for two hours before and after bombardment markedly enhanced transformation frequency. A total of six genetically modified plantlets were regenerated, and transgene integration was validated via PCR.

To evaluate promoter activity, a fluorometric assay measuring uidA (GUS) gene expression was conducted. Results demonstrated that the maize Ubi-1 promoter outperformed the CaMV 35S promoter by 1.4-fold and surpassed the TaBV-600 promoter by 23-fold. These findings offer a platform for advancing taro improvement through genetic transformation and future gene-editing strategies, contributing to the development of resilient cultivars of this underutilized crop.