Hunt for Easter tree

British scientists are behind an international rescue bid to return a flowering hardwood tree, now extinct in the wild, to its native Pacific home of Easter Island.

The toromiro tree, Sophora toromiro, was used by Polynesian islanders to carve miniature copies of the huge stone heads which surround the island 3,700 km off Chile.

Now scientists from the University of Reading and Kew Gardens are working with Chilean counterparts using the latest DNA fingerprinting to return toromiro home.

Explorer Thor Heyerdahl visited the island on his Kontiki expedition and collected some of the last tree seeds in the 1960s. They went to Sweden where four were germinated, of which two seedlings are still alive.

"This was not enough," said Alistair Culham, lecturer in botany at the centre for plant diversity and systematics at Reading University as the gene pool was too small, scientists have been hunting for other undocumented plants of this species.

Dr Culham and Mike Maunder, of the Royal Botanical Gardens at Kew, have managed to extract DNA from samples collected in the 1800s. By comparing the two sources, a DNA fingerprint has been identified.

The five-year hunt, including work by Alberto Bordeu from Chile, has turned up eight genotypes: four in Chile, three in Australia and the one in Sweden. "Eight different genotypes should be enough diversity to start a breeding programme to take this plant back to Easter Island," said Dr Culham.