Quick Dips

Forest Fungus Fingered

New Zealand's forestry industry could save millions of dollars each year if Massey University research is successful. University geneticist Dr Rosie Bradshaw is investigating a fungus which infects Pinus radiata, causing needles to die and wood yield to be reduced.

The fungus, known as Dothistroma pini, was first noticed in New Zealand in 1962 and is now established in the North and South Islands. Methods to combat the disease are focusing on inactivating a toxin thought to be involved, but Bradshaw is establishing whether the toxin is responsible for causing the disease.

"We are also comparing the types and arrangement of genes in the toxin's biosynthesis with those in the fungus Aspergillus flavus, involved in biosynthesis of the potent, cancer-causing aflatoxin."

Bradshaw has been surprised by similarities between the arrangment of the genes controlling toxin production in Dothistroma and Aspergillus, as it suggests they may have had a common ancestor.

"This is interesting from an evolutionary point of view as well as when considering whether Dothistroma pini may develop the capacity to also produce aflatoxins."

The other main theme of Bradshaw's research is investigating the genetic variability of the fungus in New Zealand. Fungi can reproduce both identical offspring (asexual) and offspring of new genetic types (sexual reproduction). Only one form of the fungus has been found in New Zealand, suggesting it was introduced only once.

"But we are planning to look at DNA profiles of Dothistroma pini from other parts of the world because if new forms arrive here they may be more virulent -- and therefore more expensive and difficult to control."

The Forest Research Institute is interested in whether a sexual form of the fungus exists in New Zealand, as this form would have greater genetic variability and hence potentially greater resistance to control methods. It is also dispersed by the wind, giving it a potentially greater range than the form already here; the latter is spread by rain-splash dispersal.