Somatic embryogenesis and plant regeneration from leaf of the interspecific hybrid of mahogany ( Swietenia macrophylla King × S. mahagoni (L.) Jacq.)

Key Message A protocol for somatic embryogenesis here described, open the possibility for the clonal propagation of selected trees of the natural hybrid of mahogany Swietenia macrophylla King × S. mahagoni (L.) Jacq. Abstract Young leaves were collected from greenhouse plants cloned from epicormic shoots of a 35-year-old interspecific hybrid of mahogany ( Swietenia macrophylla King × S. mahagoni (L.) Jacq.) tree. All explants formed calli when cultured on a medium containing Murashige and Skoog salts, 3% sucrose (Lobachemie), 0.3% Phytagel (Sigma) and 4.52 µM 2,4-dichlorophenoxyacetic acid and regardless of the concentration of kinetin used (4.65, 9.29 or 13.94 µM). After 3 months, the calli were separated from the leaf segments and subcultured on differentiation medium. The greatest number of calli (38–40%) forming somatic embryos, after 6 months of culture, was obtained on the differentiation media containing 4.44 or 6.66 µM benzyladenine (BA). Secondary or repetitive somatic embryogenesis was achieved when primary cotyledonary somatic embryos were subcultured on fresh medium of the same composition as differentiation medium containing 4.44 µM BA. Numerous cotyledonary somatic embryos were developed after 5 weeks of subculture on differentiation medium with decreased BA concentration (1.77 µM). Thereby, developed somatic embryos had different morphological features, which are described herein. The highest frequency of somatic embryo germination (62%) was obtained using half-strength MS medium supplemented with 0.27 µM of BA plus 0.145 µM of gibberellic acid. Twenty-five percent of the plantlets developed normally in the greenhouse. In this study, a somatic embryogenesis system was established from leaf explants of a natural hybrid of mahogany Swietenia macrophylla King × S. mahagoni (L.) Jacq was established, hence opening the possibility for the clonal propagation of selected trees of this natural hybrid.