Somatic hybridization of caipira sweet orange and rangpur lime via protoplast fusion

Author(s)

Fernanda Januzzi Mendes da Gloria

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 1998-11-05
• Advisor: Francisco de Assis Alves Mourao Filho

Abstract

The objective of this research was to produce citrus somatic hybrid via protoplast fusion be used as a citrus rootstock. Preliminary experiments involved calli induction of seven citrus cultivars to be used on protoplast isolation and fusion experiments. The cultivars were: Cravo and Ponkan mandarins (Citrus reticulata Blanco), Murcott tangor (Citrus reticulata Blanco x Citrus sinensis L. Osbeck), Serra dágua, Natal, Valência and Pera sweet oranges (Citrus sinensis L. Osbeck). Fifity nucelli of each cultivar were introduced onto three different culture media (EME, ½-EME and EBA). Embryogenic calli were obtained in all cultivars, except on Pera sweet orange, that produced only hard calli. Parallel with the above experiment, it was developed another experiment to evaluate different carbon sources on somatic induction of embryogenesis in calli of Caipira sweet orange (C. sinensis) + Cleopatra mandarin (Citrus reshni Hort. ex Tanaka), Caipira sweet orange (C. sinensis) + Florida Rough lemon (Citrus Jambhiri Lushington), Pera sweet orange (Citrus sinensis L. Osbeck) + Cleopatra mandarin (C. reshni), Rangpur lime (C. limonia) + Sour orange (Citrus aurantium L.) fusions. The basic culture media was MT + malt extract (500 mg 1-1) with sucrose (0,I45M), lactose (0.I45M), maltose (0,I45M) or galactose (0,1M) + sorbitol (0,1M). The sugar that best stimulated somatic embryogenesis was maltose, followed by lactose, galactose + sorbitol and sucrose, except on Caipira sweet orange + Cleopatra mandarin combination, where galactose + sorbitol was the second best sugar rather than lactose. Protoplast fusion experiment of Caipira sweet orange (Citrus sinensis L. Osbeck) + Rangpur lime (Citrus limonia L. Osbeck) were induced by chemical method, with poliethylene glycol (PEG) solution. Protoplasts were cultured on liquid medium. Microcalli were transfered to semi-solid EME medium. Somatic embryogenesis was observed 60 days after culture. Somatic embryos were germinatated on EME + 0,5 mg 1-1 GA3. Four, out of 39 regenerated plants were confirmed as somatic hybrids by leaf morfological evaluation, chromossome counting and RAPD analyses. (AU)