Somatic Embryogenesis in Citrus spp.: Carbohydrate Stimulation and Histodifferentiation

• Published in: In vitro cellular & developmental biology. Plant Vol. 37; no. 4; pp. 446 - 452
• Main Authors: TOMAZ, Marcio L, JANUZZI MENDES, Beatriz M, MOURAO FILHO, Francisco De Assis A, DEMETRIO, Clarice G. B, JANSAKUL, Naratip, MARTINELLI RODRIGUEZ, Adriana P
• Format: Journal Article
• Language: English
• Published: Wallingford CABI Publishing 01.07.2001; Cambridge University Press
• Subjects: Auxins; Biological and medical sciences; Biotechnology; Callus; Developmental Biology/Morphogenesis; Embryogenesis; Embryos; Eukaryotic cell cultures; Fundamental and applied biological sciences. Psychology; Histology; In vitro propagation: entire plant regeneration from tissues and cell cultures; Methods. Procedures. Technologies; Plant cells; Plant cells and fungal cells; Plants; Somatic embryogenesis; Somatic embryos; Subcultures; Citrus sinensis; Sucrose; Citrus fruit; Citrus reticulata; Rutaceae; Tissue culture; Glucose; Somatic embryo; Dicotyledones; Angiospermae; Carbohydrate; Chemical composition; Developmental stage; Intraspecific comparison; Culture medium; Embryonic development; Nutrition; Glycerol; Histology; Micropropagation; Maltose; Cell differentiation; Regeneration; Lactose; Spermatophyta; Galactose; Cultivar
• ISSN: 1054-5476; 1475-2689
• DOI: 10.1007/s11627-001-0078-y

Somatic embryogenesis from nucellus-derived callus cultures of five cultivars, including three (Caipira, Seleta Vermelha, and Valencia) of sweet oranges (C. sinensis L. Osbeck), Rangpur lime (C. limonia L. Osbeck), and Cleopatra mandarin (C. reticulata Blanco) (lines I and II), were studied. Callus lines maintained on MT medium supplemented with$50 g l^{-1}$sucrose were transferred to MT medium supplemented with different carbohydrate sources: galactose, glucose, lactose, maltose, or sucrose at 18, 37, 75, 110, or 150 mM, or glycerol at 6, 12, 24, 36, or 50 mM. Globular embryos were observed after approximately 4 wk, in several treatments. Cultures of Valencia and Caipira sweet oranges and Cleopatra mandarin (line I) showed high numbers of embryos on medium containing galactose, lactose, and maltose. Histological studies showed somatic embryos in all developmental stages with a normal histodifferentiation pattern. The other two cultivars (Rangpur lime and Cleopatra mandarin, line II) formed very few embryos, which did not develop further following the globular stage. Some of the abnormalities observed were lack or dedifferentiation of protoderm and absence of apical meristems and procambial strands. Embryos that followed the normal sequence of development were easily converted into plants. Non-embryogenic cultures continued as proliferating callus cultures, eventually forming a few embryos which did not convert into plants. Statistical analyses of the callus response to carbohydrate treatments was done using an overdispersion Poisson model.