Plant & Animal Genome IX Conference

Workshop: Forest Tree Genome Mapping
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MOLECULAR DIFFERENTIATION BETWEEN TWO EUROPEAN OAK SPECIES: QUERCUS ROBUR AND QUERCUS PETRAEA

¹ INRA, Equipe de Génétique et d'Amélioration des Arbres Forestiers-Cestas 33610, France

² INRA, Equipe d'Ecophysiologie Forestiére -Champenoux 54280, France

Q. petraea and Q. robur are two closely interfertile species that exhibit phenotypic differences but only show extremely low genetic differentiation for isozymes, chloroplast or nuclear DNA markers. Morphological characters (petiole length, hairiness and number of intercalary veins), and physiological traits related to anoxia and drought stress response, are among the main features involved in species differences. With the main goal of identifying genomic regions involved in the molecular differentiation of the two species, a threefold approach is conducted: (1) a molecular approach (cDNA-AFLP) to identify genes involved in response to anoxia or drought stresses; (2) a physiological approach to subdivide response to abiotic stresses into various components (enzyme activity, biomass allocation, stomatal conductance, rate of CO2 assimilation); (3) a statistical approach based on QTL detection for traits related to leaf morphology and response to abiotic stresses. Two parental maps were first established from the segregation of 500 markers (AFLP, RAPD, isozymes, microsatellites and STS) in a full-sib family of Quercus robur (278 offspring). The codominance and random distribution of 50 microsatellites, allows to define homology between linkage groups of both parental maps and made it possible to construct a consensus map. QTL and candidate genes are now being mapped to investigate whether genes that differentiate both species are clustered on particular linkage groups or dispersed all over the genome.