Plantlet regeneration from cotyledon, cotyledon petiole, and hypocotyl explants via somatic embryogenesis pathway in roquette (Eruca sativa Mill)

Abstract

A high-efficiency plant regeneration protocol based on somatic embryo formation for Huining Roquette, an interesting ecotype of Eruca sativa Mill, was established for future transgenic applications. On Murashige and Skoog (MS) medium containing 2,4-dichlorophenoxyacetic acid (2,4-D), alone or in combination with 6-benzylaminopurine (BA) or kinetin (KT), the cotyledon explants, cotyledon petioles, and hypocotyls all produced embryogenic callus (ECs) or somatic embryos (SEs) to different extents. After transferring onto hormone-free MS medium, the ECs or SEs from the different explants and media, all of them developed shoots with a frequency of 6–48%, and then produced roots with a frequency of 2–29%. As regards the probability of shoot differentiation, cotyledon explants appeared similar to hypocotyls, but superior to cotyledon petioles; 2,4-D + KT worked more effectively than 2,4-D alone and 2,4-D + BA for callus induction and shoot differentiation. The optimal hormone combinations for plant regeneration of cotyledon, cotyledon petiole, and hypocotyl explants were 1.0 mg/l 2,4-D + 0.1 mg/l KT, 0.8 mg/l 2,4-D + 0.3 mg/l BA, and 1.0 mg/l 2,4-D + 0.3 mg/l KT, respectively. MS medium with 60–80 g/l sucrose was the most effective for improving SE maturation and germination.

Keywords:

• Embryogenic callus
• Eruca sativa Mill
• plant regeneration
• somatic embryo

Acknowledgements

The authors are sincerely grateful to Dr. Natalie Maor (Department of Chemistry, Georgia State University, USA) for helpful comments and linguistic review of the manuscript.