Dinucleotide microsatellites from Eucalyptus sieberi: inheritance, diversity, and improved scoring of single-base differences

Eight dinucleotide microsatellites were developed in Eucalyptus sieberi L. Johnson (silvertop ash), a member of the subgenus Eucalyptus. Transfer of s ix of these to the subgenus Symphyomyrtus and their Mendelian inheritance a re demonstrated using a full-sib cross in Eucalyptus nitens. Genetic divers ity parameters are presented for the eight loci based on a sample of 100 ol d-growth E. sieberi trees from a single natural stand. One locus, Es266, ha d an atypically high fixation index, and significantly deviated from Hardy- Weinberg equilibrium genotypic proportions, indicating the likely presence of null alleles. Two of the loci, Es076 and Es140, had many alleles that di ffered in size by only a single base pair, possibly because of short poly(A ) or poly(T) stretches in their flanking regions. These two loci were by fa r the most polymorphic, but were difficult to score reliably on a capillary DNA sequencer. Reliability of scoring of these two one-base microsatellite loci was markedly improved by the incorporation of internal reference alle les into each sample analysed.