MAPPING CANDIDATE GENES IN EUCALYPTUS

¹ Cirad forêtCampus international de BaillarguetBP 503534032 Montpellier Cedex 01FRANCE

² UMR CNRS/Université Paul Sabatier n°5546Pôle de Biotechnologies Végétales24 chemin de Borde RougeBP 17, Auzeville31326 Castanet TolosanFrance

³ Laboratoire de Génétique et Amélioration des arbres forestiersINRA- BP 45F-33610 Cestas

We used the single-strand conformation polymorphism (SSCP) technique to map six genes on Eucalyptus urophylla and Eucalyptus grandis linkage maps. These included four genes involved in the common phenylpropanoid pathway (Caffeic acid 3-O-methyltransferase, Caffeoyl CoA 3-O-methyltransferase, 4-Coumarate CoA ligase and phenylalanine ammonia-lyase), two genes involved in the " lignin specific " pathway (Cinnamoyl CoA reductase and Cinnamyl alcohol dehydrogenase). The placement of these genes on the Eucalyptus maps was carried out using an interspecific hybrid mapping population. This will further facilitate the identification or exclusion of " positional " candidate genes for characterizing quantitative trait loci (QTL) for traits related to wood quality. We have studied colocations between these candidate genes and QTL for longitudinal growth strain and wood density. The 4-coumarate CoA gene seems to be a good candidate for wood density as measured by pilodyn.