title: Somaclonal variation in micropropagated oil palm. Characterization of two novel genes with enhanced expression in epigenetically abnormal cell lines and in response to auxin.
abstract: 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 increased 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 accumulated 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.
authors.affiliation: CIRAD/IRD Oil Palm Laboratory, UMR 1098, Centre IRD Montpellier, BP 64501, 911, avenue Agropolis, 34394 Montpellier, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Morcillo
authors.forename: Cyrill
authors.initials: C
authors.lastname: Gagneur
authors.forename: Hélène
authors.initials: H
authors.lastname: Adam
authors.forename: Frédérique
authors.initials: F
authors.lastname: Richaud
authors.forename: Rajinder
authors.initials: R
authors.lastname: Singh
authors.forename: Suan-Choo
authors.initials: SC
authors.lastname: Cheah
authors.forename: Alain
authors.initials: A
authors.lastname: Rival
authors.forename: Yves
authors.initials: Y
authors.lastname: Duval
authors.forename: James W
authors.initials: JW
authors.lastname: Tregear
mesh_terms: D000595:Amino Acid Sequence; D028023:Arecaceae / Q000187:drug effects / Q000196:embryology / Q000235:genetics*; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D046509:Tissue Culture Techniques
chemical_list: D018744:DNA, Plant; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012333:RNA, Messenger