In vitro protocol for bud induction from adventitious roots and hydroponic acclimatization of purple sweet potato (Ipomoea batatas (L.) Lam)

Key message The present study developed a protocol for bud induction from adventitious roots of purple sweet potato and a new method for acclimatizing regenerated seedlings by hydroponics. A fast and efficient genetic transformation pathway is needed for sweet potato transgenics and acclimatization of regenerated plants also needs to be studied. In this experiment, purple sweet potato leaves were used as explants. By adding different hormones at different stages, callus was induced first and then adventitious roots and buds were induced. An acclimatization method with a high survival rate was also found. A new efficient in vitro plant regeneration system characterized by rapid sequential organogenesis using leaf explants has been developed in sweet potato. Optimal plant regeneration was obtained in the variety Ning Purple Potato No. 1 with a four-step protocol. The first stage was callus induction of leaf explants for 40 days on Murashige and Skoog medium containing 0.8 mg/L 2,4-D. The second stage was adventitious root induction from callus on solid MS medium with different combinations of 6-BA and NAA; 0.6 mg/L 6-BA and 0.3 mg/L NAA was the best combination to induce adventitious roots. The third stage was adventitious bud induction from adventitious roots; solid MS medium with 2.0 mg/L ZT, 1.0 mg/L KIN and 1.0 mg/L GA(3) produced the maximum of number of adventitious buds after 12 weeks. The fourth stage was acclimatization to hydroponics. The best acclimatization program was floating culture in Hoagland nutrient salts solution for 7 days. We have developed an efficient protocol to generate plants and the regenerated plants survived acclimatization and transplantation. As the method is simple, rapid and reproducible, it may be valuable for transgenic genetic improvement.

Automated summary

A protocol for bud induction from adventitious roots of purple sweet potato and a new method for acclimatizing regenerated seedlings by hydroponics were successfully developed in this study. The use of purple sweet potato leaves as explants, along with different hormones at different stages, resulted in the induction of callus, adventitious roots, and buds. A highly efficient plant regeneration system in sweet potato was established, which may be valuable for transgenic genetic improvement.