Conservation of xylem preferentially expressed tags in several subgenera of Eucalyptus l'Hérit.
2005
Gion, Jean-Marc | Cabannes, Emmanuelle | Poitel, Mireille | Vigneron, Philippe
Large eucalypt genomic resources, especially expressed sequence tags (ESTs), have been recently developed using a limited number of economically important species of the subgenus Symphyomyrtus. The usefulness of these databases to describe and use the huge genetic diversity of the genus relies on the sequence conservation. In this study, primers designed from a set of 19 ESTs isolated from E. gunnii xylem (subgenus Symphyomyrtus, section Maidenaria) were used to amplify putative homologous genes in 30 species of Eucalyptus L'Hérit., (nineteen Symphyomyrtus, five Monocalyptus, two monotypic subgenera Nothocalyptus and Idiogenes and four Corymbia). Specific PCR products were compared between genotypes according to their length. Verification of the amplified fragment identity was performed through direct sequencing of a random sample of PCR products. Based on presence/absence of the expected band, neighbour joining tree were constructed in order to reveal genetic proximity to the reference species. The overall rate of amplification was 81%. Four EST amplified on the 89 tested genotypes. The rate of transferability decreases according to the phylogenetic distance with E. gunnii, from 94% for sections Maidenaria, Transversaria and Exsertaria, to 68% for the subgenus Monocalyptus and only 48% for the remote subgenus Corymbia. The present work shows the high potential of eucalypt ESTs for comparative mapping and association studies between candidate genes and quantitative traits at subgenus or genus level. (Texte intégral)
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