STORAGE RESERVES IN PECAN SOMATIC EMBRYOS DERIVED FROM SUSPENSION-CULTURE

Pre-globular stage embryo masses from hormone-free liquid suspension cultures of pecan (Carya illinoinensis Koch) have been induced to develop into somatic embryos (SE) on semi-solid medium; however, plant recovery from these embryos has been poor. Lack of storage reserve accumulation may be a critical factor. In this study, the effect of modified solid media treatments on somatic embryo storage reserve accumulation was appraised. Media were modified with various combinations of abscisic acid, maltose, casein hydrolysate, and filter paper overlays. Embryos were assessed for triglyceride and protein accumulation, compared with levels found within zygotic embryos. High concentrations of maltose with sucrose generated reserves in the somatic embryos more closely approaching mature zygotic embryos. Although some treatments stimulated significant reserve deposition, this was associated with unacceptable degeneration in embryo morphology. In general, embryos were repetitive (perpetually undergoing renewed rounds of embryogenesis) while on the various media. Reserve-enhancing treatments were identified which may benefit plant recovery from suspension-derived pecan somatic embryos.