Somatic embryogenesis in butternut, Juglanscinerea
Immature cotyledonary explants excised from developing fruits of Juglanscinerea L. were cultured in vitro to induce regeneration of somatic embryos. Somatic embryos were initiated directly on cotyledons collected 9 weeks postanthesis and cultured on a Driver and Kuniyuki medium supplemented with 250 mg/L L-glutamine, 0.01 mg/L indole-3-butyric acid, 1 mg/L 6-benzylaminopurine, and 2 mg/L kinetin for 3 weeks, prior to transfer to hormone-free Driverand Kuniyuki medium. Embryogenic callus was initiated on explants collected 8–11 weeks postanthesis and cultured on two different media formulations containing 0.25 mg/L 6-benzylaminopurine and 2 mg/L 2,4-dichlorophenoxyacetic acid for 3 weeks, prior to transfer to hormone-free media. Globular to mature somatic embryos were differentiated, and conversion of somatic embryos into whole plants was incomplete. Competence of embryogenic callus was maintained for 1 year with regular subculturing on hormone-free media.