Regeneración in vitro mediante embriogénesis somática de variedades de cítricos. I. Obtención de callo friable y suspensiones celulares de naranja dulce (Citrus sinensis) y naranja agria (Citrus aurantium) cultivadas en Costa Rica

Abstract

In vitro plant regeneration of citrus through somatic embryogenesis. I. Establishment of friable calli and suspension cultures of local cultivars of sweet orange (Citrus sinensis) and sour orange (Citrus aurantium). Friable calli of the sweet orange cvs. 'Acosta 6' and 'Washington Navel', as well as sour orange, were initiated from immature embryos cultured in vitro. Formation of friable callus was observed only with the addition of a cytokinin on sweet orange cultivars and of malt extract on sour orange, respectively. Callus induction was a slow process, requiring 7 to 10 months in culture, with subculture every month. The growth rate of calli fluctuated, showing the same behavior small plant materials. From small quantities of friable callus, multiplication allowed obtainment of sufficient calli to start cell suspension cultures in both sweet orange cultivars, which were successfully established and maintained forfour months. Power shortages that left the flasks in a stationary position for some hours induced the suspension cultures to initiate the embryogenic process,ceasing their multiplication. The factors that affect the formation of the calli and the induction of somatic embryogenesis are discussed.