Restriction fragment length polymorphisms in chloroplast DNA from six species of eucalyptus

Chloroplast DNA was extracted from six species of Eucalyptus (E. perriniana, E. nitens, E. ovata, E. regnans, E. amygdalina and E. risdonii). Digests with four restriction enzymes (Hind III, Xho I, Nco I and Eco RV) revealed restriction fragment length polymorphisms (RFLPs) between subgenera, between species and within species. However, no variation in fragment pattern was detected with Sac II or Pst I. The subgenera Monocalyptus and Symphyomyrtus were clearly differentiated by their RFLP patterns where, with the exception of one outlying specimen of E. amygdalina, 45% of all polymorphic fragments were specific to one or other subgenus.

While species from different subgenera and series were well differentiated, it was more difficult to differentiate species within series with the low sample sizes used. However, the average net divergence between species increased with increasing taxonomic distance between species, from 0.02% within series and 0.20% between species from different series within subgenera, to 0.99% of nucleotides per nucleotide site for species from different subgenera. Based on Eco RV digests, the eucalypt chloroplast genome was estimated at 143 kb.