Initiation and Maintenance of Cell Suspension Cultures of Two Citrus Species for Protoplast Isolation.

Cell suspension cultures were initiated from six month old ovule-derived embryogenic calli of two Citrus species named Citrus aurantifolia (Christm.) Swingle cultivar Sweet lime and Citrus reticulata Blanco cultivar Kinnow. The growth rate of cells was observed on two different media MT basal medium + 0.5 g L-1 malt extract (EME) and MT containing half strength NH4NO3 and KNO3, supplemented with 1.55 g L-1 glutamine and 0.75 g L-1 KCl (H+H). Kinnow and Sweet lime cells showed a sigmoidal growth pattern on (H+H) and (EME) liquid media, when PCV was plotted against time. The logarithmic phase of cells started from 4th to 10th day and after that a stationary phase observed in cells with elongated vacuoles. This indicated that citrus cells active phase started soon after subculture and ends after two weeks. These embryogenic suspension cultures were later used for protoplast isolation which is a key step towards somatic hybridization. [ABSTRACT FROM AUTHOR]