Plant-regeneration From Callus-culture of 3 Citrus Rootstocks

Complete plants were regenerated from callus derived embryo culture of Citrus aurantium, Poncirus trifoliata and of Carrizo citrange (C. sinensis x Poncirus trifoliata) via somatic embryogenesis and organogenesis. Isolated embryoids were differentiated on medium containing 1000 to 1500 mg l-1 malt extract. Both embryoids and shoots were obtained by the use of plant growth regulators: NAA and BAP. The highest frequency was obtained with 1 mg l-1 NAA + 5 mg l-1 BAP in Poncirus trifoliata and citrange but with 1 mg l-1 NAA + 10 mg l-1 BAP in C. aurantium. Rooting was promoted by a supplement of 1 mg l-1 GA3 or 1 mg l-1 NAA. GA3 enhanced stem elongation and rooting in embryoids and NAA stimulated adventitous root formation

Nacl-tolerant Plants of Poncirus-trifoliata Regenerated From Tolerant Cell-lines

Salt-tolerant cell lines of citrus rootstock (Poncirus trifoliata cv Pomeroy) were selected by subculturing embryo-derived calli on media containing sublethal concentrations of NaCl (5 and 10 g/l). Selected lines showed a normal growth in the presence of salt at the concentrations used for selection, and salt tolerance persisted after a passage on a salt-free media. Their K+ and Ca2+ content remained higher than in control cells for increasing NaCl concentration in the medium, suggesting a modification of cell membrane permeability as the main cause of NaCl tolerance. Shoots and plants regenerated from selected cell lines showed improved growth and salt tolerance. Calli induced from these plants tolerated a salt concentration of 10 g/l, indicating the persistance of the selected trait