Embryogenic calli induction from nucellar tissue of Citrus cultivars

Abstract

Nucellar tissues of seven Citrus varieties were introduced onto three growth media to produce embryogenic callus. The media tested were: EME [MT, modified, with the addition of malt extract (500 mg.L-1)]; 1/2-EME [half concentration of MT macronutrients + half concentration of BH3 macronutrients + 500 mg.L-1 malt extract + 1.55 g.L-1 of glutamine]; and EBA [EME + 0.44 muM 6-benzyladenine + 0.04 muM 2,4 D]. Soft friable calli were obtained from 'Cravo' and 'Ponkan' mandarins (Citrus reticulata, Blanco), 'Murcott' tangor (Citrus reticulata Blanco x Citrus sinensis L. Osbeck), 'Serra d'água' and 'Valencia' sweet oranges (Citrus sinensis, L. Osbeck) 120 days after callus induction. 'Natal' and 'Pera' sweet oranges (Citrus sinensis, L. Osbeck) produced hard non-friable calli in this period. EME and 1/2-EME media had the best results for 'Cravo' mandarin, 'Ponkan' mandarin and 'Serra d'água' sweet orange, whereas EBA was the best media composition to induce soft friable calli on 'Murcott' tangor and 'Valencia' sweet orange. Friable callus cultures of 'Cravo' and 'Ponkan' mandarins, and 'Murcott' tangor yielded high quality protoplasts after isolation. Abbreviations: a.c. - activated charcoal; BA - 6-benzyladenine; IAA - indole-acetic acid; 2,4-D - 2,4-diclorophenoxyacetic acid; MT - Murashige & Tucker basal medium.

Keywords

• biotechnology
• tissue culture
• cultivar improvement
• growth regulator
• protoplast