Stable Production of Transgenic Pepper Plants Mediated by Agrobacterium tumefaciens

The aim of this study was to establish a stable transformation method for hot pepper using the hygromycin phosphotransferase (hpt)/hygromycin selection strategy. Explants from aseptic pepper seedlings were inoculated with Agrobacterium tumefaciens carrying pCAMBIA1301. A number of calli were developed on the medium containing hygromycin to discriminate the induction of “false-positive buds,” and then shoots were successfully regenerated from the hygromycin-resistant calli. Southern and Northern hybridization analysis indicated that the hpt gene was integrated and expressed in the transgenic pepper plants (T0) and transmitted to the progeny (T1) without genetic modification. Most T1 progenies derived from self-pollination revealed a 3:1 segregation ratio for hygromycin resistance, indicating that one copy of the T-DNA was integrated into the respective transgenic lines. Both uidA and hpt genes were stably expressed in the T1 generation and coinherited in the progenies. Finally, homozygous progenies were identified in the T1 generation of the transgenic peppers, and the homozygous state was maintained in all progenies tested (T2). The results show the reliability and stability of the hpt/hygromycin selection protocol for pepper transformation.