Fusão de protoplastos visando a reconstrução da laranja azeda

Abstract

PROTOPLAST FUSION AIMING THE RECONSTRUCTION OF SOUR ORANGE The aim of this work was to apply the technique of chemical fusion of protoplasts, in order to develop interspecific somatic hybrids between mandarins (Citrus reticulata) and pummelos (Citrus grandis), in order to produce similar to sour orange (Citrus aurantium). The sources for protoplasts were embryogenic suspension cultures of 'Page' tangelo (C. reticulata x C. paradisi) and 'Murcott' tangor (C. reticulata x C. sinensis) and young leaves from seedlings of 'Lau Tau' and 'Ogami' pummelos (Citrus grandis). After the fusion, the protoplasts were cultivated in the absence of light, until the formation of microcolonies, and were then cultivated in double-phase EME medium, supplemented with 13.33 g/L of maltose for embryogenesis induction. The globular embryos thus formed were transferred to EME medium with 25 g/L of sucrose and, when in cotyledonal stage, were transferred to a culture medium supplemented with 1.5 g/L of malt extract. The shoots obtained were grafted in vitro onto 'Hamlin' and 'Valencia' sweet oranges. The regenerated plants were cultivated in a greenhouse, over commercial substrate. In this process, 17 plants were obtained. These plants presented phenotypic conformation different from the genitors, with leaves with reduced size, round apex, dark green coloration, rough leaf blade and absence of developed petiole. The analysis by flow cytometry confirmed the diploid character of the regenerated plants. RAPD molecular markers presented a similar band pattern between the regenerated specimen and the genitor 'Page' tangelo. The protocol used for isolation, hybridization and cultivation of protoplasts, as well as for the regeneration and acclimatization of the plants allowed the obtainment of 17 plants from the combination of 'Page' tangelo + 'Lau Tau' pummelo, with phenotypic conformation different from the genitors, two plants from the combination of 'Murcott' tangor + 'Ogami' pummelo and one plant from the combination of Murcote' tangor + 'Lau Tau' pummelo.