Somatic embryogenesis of a seedless sweet orange (Citrus sinensis (L.) Osbeck)

Somatic embryogenesis is an important in vitro technique used to obtain Citrus sinensis (L.) Osbeck (sweet orange) plantlets for conservation, sanitation, propagation, and breeding. The induction of somatic embryogenesis from adult tissues of sweet orange could be an alternative to in vitro organogenesis from epicotyl segments, especially in seedless cultivars, where the latter is not feasible. The aim of this study was to obtain plantlets from ovary-derived somatic embryos of sweet orange cv. 'Washington Navel', an important seedless cultivar for citrus fresh fruit production. The explants used were pistils from flower buds, pre-anthesis, from 20-y-old plants cultivated in the field. Forty plantlets from 47 somatic embryos were obtained, in vitro-grafted, and acclimatized in greenhouse conditions. Ploidy evaluation through flow cytometric analysis, as well as the results of target region amplification polymorphism (TRAP) molecular markers confirmed the somatic origin of embryos as genetically similar to donor plants. This technique could be used for obtaining embryogenic cell suspension cultures or regenerated plants from mature tissues other than seed-derived tissues, especially for seedless genotypes.