DNA fingerprinting of Eucalyptus graniticola: a critically endangered relict species or a rare hybrid?

摘要

E. graniticola is known from a single plant located on a granite outcrop south-east of Perth in Western Australia. Since its discovery in 1987, it has been uncertain whether this eucalypt is a relict species or a hybrid. The similarity of features such as leaf, bud and fruit morphology, to those of E. rudis, a common tree found in the vicinity, suggested that E. graniticola is a hybrid. RAPD was used to demonstrate the additive inheritance of DNA markers from E. rudis and E. drummondii, the putative parent species, in E. graniticola. All the markers detected for E. graniticola using 9 primers were shared with either E. rudis (40%), E. drummondii (35%) or both parent species (25%). These results, combined with factors such as the segregation of cotyledon morphology, suggest a hybrid origin for E. graniticola. Therefore, it is suggested that conservation of this rare eucalypt should rely more on ex situ propagation and storage than on active management.