In vitro plant regeneration from callus of Citrus x monstruosa (Pompia), an endemic citrus of Sardinia.

A regeneration protocol was developed from callus obtained from various explants taken from in vitro cultured seedlings (root, leaf and stem internodes) of Citrus x monstruosa. The best treatment in terms of response frequency and mean number of shoots for explants was 35.0 microM BA with 5.5 microM NAA. The best shoot regeneration was obtained with internodal stem segments cut longitudinally with the cut surface in contact with the culture medium and pre-treatment of 21 days of these explants in darkness. The best rooting of explants was obtained on half-strength MS basal medium supplemented with either NAA or IBA at 5.4 microM and 2.5 microM, respectively. Hardening of Citrus x monstruosa was accomplished in 40 days, with 95% survival rate.