AOBPreview originally published online on May 21, 2003
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Annals of Botany 92: 129-136, 2003
© 2003 Annals of Botany Company
Proliferation, Maturation and Germination of Castanea sativa Mill. Somatic Embryos Originated from Leaf Explants
1 Instituto de Investigaciones Agrobiológicas de Galicia, CSIC, Apartado 122, 15080 Santiago de Compostela, Spain
* For correspondence: Fax: +34 981592504, e-mail: amvieitez{at}iiag.cesga.es
Received: 6 November 2002; Returned for revision: 7 February 2003; Accepted: 17 March 2003 Published electronically: 21 May 2003
Experiments were performed to determine the influence of proliferation medium on the maintenance of embryogenic competence and on repetitive embryogenesis in Castanea sativa Mill. somatic embryos derived from leaf explants. Somatic embryo proliferation was carried out by both direct secondary embryogenesis and by the culture of nodular callus tissue originated from cotyledons of somatic embryos. Both systems led to the production of cotyledonary somatic embryos on Murashige and Skoog proliferation medium supplemented with 0·1 mg l1 benzyladenine and 0·1 mg l1 naphthaleneacetic acid. Carbon source and concentration had a marked influence on maturation and subsequent germination ability of chestnut somatic embryos. Plantlet conversion was achieved in embryos matured on media with 6 % sucrose, and on 3 or 6 % maltose, whereas mean shoot length, root length and leaf number of produced plants were not significantly affected by these maturation media. Overall, the best results were obtained with 3 % maltose-matured somatic embryos, giving rise to 6 % plant recovery in addition to 33 % of embryos exhibiting only shoot development. The application of a 2-month cold treatment at 4 °C to somatic embryos matured on medium with 3 % maltose was necessary for achieving plant conversion, while partial desiccation did not appear to influence this response. A total of 39 % of embryos eventually produced plants either through conversion to plantlets or indirectly through rooting of shoots. Shoots formed by somatic embryos could be excised, multiplied and rooted following the micropropagation procedures previously developed for chestnut.
Key words: Castanea sativa, chestnut, cold treatment, germination, plant conversion, secondary embryogenesis, somatic embryogenesis.