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Nucleotide diversity was assessed within nine candidate genes (CGs) (in total 4.6 kb) for the time of bud burst in nine sessile oak (Quercus petraea) populations distributed in central and northern Europe. The sampled populations were selected on the basis of their contrasting times of bud burst observed in common garden experiments (provenance tests). The CGs were selected according to their expression profiles during the transition from quiescent to developing buds and/or their functional role in model plants. The overall nucleotide diversity was large (πtot=6.15 × 10−3; πsilent=11.2 × 10−3), but population differentiation was not larger than for microsatellites. No outlier single-nucleotide polymorphism (SNP) departing from neutral expectation was found among the total of 125 SNPs. These results contrasted markedly with the significant associations that were observed between the CGs and bud burst in segregating populations. Quantitative trait loci (QTLs) for bud burst were identified for 13 year*site seasonal observations in a cloned mapping pedigree. Nineteen QTLs were detected, and QTLs located on linkage groups 2, 5 and 9 contributed repeatedly to more than 12% of the phenotypic variation of the trait. Eight genes were polymorphic in the two parents of the pedigree and could be mapped on the existing genetic map. Five of them located within the confidence intervals of QTLs for bud burst. Interestingly, four of them located within the three QTLs exhibiting the largest contributions to bud burst. [ABSTRACT FROM AUTHOR]

Genomic regions differentiating Quercus petraea and Quercus robur were detected by screening 2800 PCR amplification products using random primers on 22 trees of each species sampled in 11 natural populations. Only two per cent of the amplified fragments exhibited significant frequency differences between the two species and none of them was specific to a species. The nucleotide divergence between the two species estimated with RAPD data was 0.5 per cent in the overall genome and increased to 3.3 per cent in the discriminant regions. Twenty-three informative fragments were cloned and partially sequenced. New primers were derived from these sequences to obtain Sequence Characterized Amplified Region (SCAR) fragments. Southern blot experiments indicated that the SCARs were generally in low copy number in the genome. A search for similarity between SCAR sequences and sequences contained in data banks revealed that three of them corresponded to known DNA sequences. [ABSTRACT FROM AUTHOR]