Somatic embryogenesis and plant regeneration from floral explants of cacao (Theobroma cacao L.) using thidiazuron

• Published in: In vitro cellular & developmental biology. Plant 1998-10, Vol.34 (4), p.293-299
• Main Authors: Li, Z. (Pennsylvania State University, University Park.), Traore, A, Maximova, S, Guiltinan, M.J
• Format: Article
• Language: English
• Subjects: 2,4-D; ANATOMIA DE LA PLANTA; ANATOMIE VEGETALE; APTITUD REGENERATIVA; APTITUDE A LA REGENERATION; Biological and medical sciences; Biotechnology; Cacao; CAL; CALLO; CALLUS; Cocoa; Cotyledons; CRECIMIENTO; CROISSANCE; CULTURE MEDIA; DESARROLLO EMBRIONARIO; Developmental Biology/Morphogenesis; DEVELOPPEMENT EMBRYONNAIRE; DOSAGE; DOSIFICACION; EMBRIOGENESIS SOMATICA; EMBRYOGENESE SOMATIQUE; Embryogenesis; EMBRYONIC DEVELOPMENT; Embryos; Eukaryotic cell cultures; EXPLANT; EXPLANTES; EXPLANTS; FLEUR; FLORES; FLOWERS; Fundamental and applied biological sciences. Psychology; GENETIC VARIATION; GENOTIPOS; GENOTYPE; GENOTYPES; GLUCOSA; GLUCOSE; GROWTH; GROWTH RATE; In vitro propagation: entire plant regeneration from tissues and cell cultures; INDICE DE CRECIMIENTO; KINETIN; KINETINE; MEDIO DE CULTIVO; Methods. Procedures. Technologies; MICROPROPAGACION; MICROPROPAGATION; MILIEU DE CULTURE; PLANT ANATOMY; Plant cells and fungal cells; Plants; QUINETINA; REGENERATIVE ABILITY; SACCHAROSE; SOMATIC EMBRYOGENESIS; Somatic embryos; SUCROSA; SUCROSE; TAUX DE CROISSANCE; THEOBROMA CACAO; THIDIAZURON; TIDIAZURON; VARIACION GENETICA; VARIATION GENETIQUE
• ISSN: 1054-5476; 1475-2689
• DOI: 10.1007/BF02822737

A procedure for the regeneration of cacao (Theobroma cacao) plants from staminode explants via somatic embryogenesis was developed. Rapidly growing calli were induced by culturing staminode explants on a DKW salts-based primary callus growth (PCG) medium supplemented with 20 g glucose per L, 9 μM 2,4-D, and thidiazuron (TDZ) at various concentrations. Calli were subcultured onto a WPM salts-based secondary callus growth medium supplemented with 20 g glucose per L, 9 μM 2,4-D, and 1.4 nM kinetin. Somatic embryos were formed from embryogenic calli following transfer to a hormone-free DKW salts-based embryo development medium containing sucrose. The concentration of TDZ used in PCG medium significantly affected the rate of callus growth, the frequency of embryogenesis, and the number of somatic embryos produced from each responsive explant. A TDZ concentration of 22.7 nM was found to be the optimal concentration for effective induction of somatic embryos from various cacao genotypes. Using this procedure, we recovered somatic embryos from all 19 tested cacao genotypes, representing three major genetic group types. However, among these genotypes, a wide range of variation was observed in both the frequency of embryogenesis, which ranged from 1 to 100%, and the average number of somatic embryos produced from each responsive explant, which ranged from 2 to 46. Two types of somatic embryos were identified on the basis of their visual appearance and growth behavior. A large number of cacao plants have been regenerated from somatic embryos and established in soil in a greenhouse. Plants showed morphological and growth characteristics similar to those of seed-derived plants. The described procedure may allow for the practical use of somatic embryogenesis for clonal propagation of elite cacao clones and other applications that require the production of a large number of plants from limited source materials.