Efficiency, genotypic variability, and cellular origin of primary and secondary somatic embryogenesis of Theobroma cacao L.

Maximova Siela N., Alemanno Laurence, Young Anne, Ferrière Nicole, Traoré Abdoulaye, Guiltinan Mark J.. 2002. Efficiency, genotypic variability, and cellular origin of primary and secondary somatic embryogenesis of Theobroma cacao L.. In Vitro Cellular and Developmental Biology. Plant, 38 (3) : 252-259.

https://doi.org/10.1079/IVP2001257

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Résumé : The development of efficient tissue culture systems for cacao holds the potential to contribute to the improvement of this tropical crop by providing a rapid and efficient vegetative propagation system for multiplication of elite genotypes. It may also find application in facilitation of germplasm movement across quarantine borders, enhancement of germplasm conservation via cryo-preservation, and development of genetic transformation systems. Somatic embryogenesis using floral tissue explants was previously the only tissue culture procedure for regeneration of cacao. We report the development of a secondary embryogenesis system utilizing primary somatic embryo cotyledon explants, which results in up to a 30-fold increase in somatic embryo production compared to primary somatic embryogenesis. The influence of genotype on the efficiency of the system was evaluated. To understand the cellular origins and developmental pathways operative in this system, we investigated the morphological changes occurring over time using light and scanning electron microscopy. While primary embryos arise from clusters of cells forming embryonic nodules, secondary embryos arise predominantly from the division of single cells, in a pathway reminiscent of zygotic embryogenesis. These results have important significance to the application of tissue culture to cacao improvement programs.

Mots-clés Agrovoc : Theobroma cacao, Embryogénèse somatique, embryon somatique, variation génétique, régénération in vitro, développement biologique, explant, analyse histocytologique

Mots-clés complémentaires : Analyse microscopique électronique

Classification Agris : F02 - Multiplication végétative des plantes
F50 - Anatomie et morphologie des plantes

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