Somaclonal variation in micropropagated oil palm. Characterization of two novel genes with enhanced expression in epigenetically abnormal cell lines and in response to auxin

Morcillo Fabienne, Gagneur Cyril, Adam Hélène, Richaud Frédérique, Singh Rajinder, Cheah Suan-Choo, Rival Alain, Duval Yves, Tregear James. 2006. Somaclonal variation in micropropagated oil palm. Characterization of two novel genes with enhanced expression in epigenetically abnormal cell lines and in response to auxin. Tree Physiology, 26 (5) : 585-594.

https://doi.org/10.1093/treephys/26.5.585

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Résumé : In vitro micropropagation based on somatic embryogenesis provides an efficient means to multiply selected genotypes of oil palm (Elaeis guineensis Jacq.). Despite its considerable potential, somatic embryogenesis can yield plants bearing a homeotic flowering abnormality known as mantled. Because the mantled abnormality is epigenetic, it cannot be detected with conventional structural molecular markers. Thus, to develop a means of discriminating among callus cultures carrying or lacking the mantled abnormality, we used a gene expression approach. We describe two novel oil palm genes, EgM39A and EgIAA1, both of which display in-creased transcript accumulation in epigenetically abnormal calli. EgIAA1 codes for an oil palm relative of the Arabidopsis thaliana (L.) Heynh. AXR3/IAA17 protein involved in early auxin response and EgM39A codes for a protein of unknown function sharing sequence similarities with asparagine synthetases. In addition to their enhanced expression in somaclonal variant callus lines, both genes displayed increased transcript accumulation in response to auxin treatment. Normal seed-derived zygotic embryos germinated in the presence of auxin ac-cumulated increased amounts of EgIAA1 transcripts after a few hours of treatment, suggesting a role in auxin response similar to that demonstrated for IAA genes in other species. The EgM39A gene also displayed enhanced transcript accumulation in auxin-treated zygotic embryos. Although only a small increase was seen after 24 h, greater changes were observed after 15 days. Both genes show potential as early markers of clonal conformity and may help to elucidate the nature of the epigenetic changes causing the mantled abnormality.

Mots-clés Agrovoc : Elaeis guineensis, micropropagation, Embryogénèse somatique, gène, auxine, trouble génétique, expression des gènes, marqueur génétique

Mots-clés complémentaires : Épigénétique

Classification Agris : F30 - Génétique et amélioration des plantes
F02 - Multiplication végétative des plantes

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

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