STABLE MAINTENANCE OF AN INTEGRATED GENE IN NUCELLAR CELLS OF NAVEL ORANGE (CITRUS-SINENSIS OSB) UNDER STORAGE IN LN(2)

Transformed nucellar cells of navel orange obtained by electroporation , were successfully cryopreserved in liquid nitrogen (LN(2)) by a vitr ification method. The cells treated with a concentrated cryoprotective solution (PVS2) at 25 degrees C for 3 min were transferred to a 1.8 m l plastic cryotube and then directly plunged into LN(2). After storage for 1 year in LN(2), cell viability was about 90%, as evaluated by fl uorescein diacetate (FDA) and phenosafranine double staining. Southern blot analysis showed that the integrated neomycin-phosphotransferase II (NTPII) gene was stably maintained in the cryopreserved-regrown cel ls without DNA alteration. No morphological differences were observed between plants regenerated from cryopreserved cells and those from non -cryopreserved cells.