EMBRYOGENIC CALLUS INDUCTION, SOMATIC EMBRYOGENESIS, REGENERATION AND HISTOLOGICAL STUDIES OF KINNOW MANDARIN (CITRUS RETICULATA BLANCO L.) FROM NUCELLAR EMBRYO AND EPICOTYL REGION

Abstract

Citrus is one of the most dominant horticultural fruit crop in the world. The objective of this study was to develop an efficient protocol for invitro embryogenic callus induction and regeneration of Kinnow mandarin. In this study, different concentrations of 2,4-D (0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mg/L) along with constant 0.5mg/L BAP were used to check the effective response of epicotyl segments and nucellar tissues on callus induction and regeneration. It was observed that MS medium containing 2.5 mg/L 2,4-D and 0.5mg/L BAP supplemented with 0.5gm/L malt extract was suitable for embryogenic callus induction from both epicotyl segments and nucellar embryonic tissues. Callus mbryogenesis was achieved on simple MS medium where as regeneration was obtained on MT medium containing 0.5mg/L BAP and 0.5mg/L Kinetin along with 0.5gm/L malt extract. It was observed that the nucellar embryos are the best explants for efficient callus induction and regeneration. In order to ensure the efficient regeneration ability of nucellar callus histological studies were performed, which showed that nucellar embryos and its calli have more chloroplasts as compared to epicotyl segments, which enhanced regeneration ability of nucellar embryos.