Botanic Gardens Trust, Sydney, Australia

Wollemi Pine research - fungal associations & pathogens

Mycorrhizal fungi grow in and on plant roots helping extract nutrients from the soil. They are thought to be particularly important in the survival of juvenile plants. Two types are associated with the roots of the Wollemi Pine: arbuscular mycorrhizae and ectendomycorrhizae. Finding two types of mycorrhizal fungi was very unexpected because previously only the arbuscular type has been found in the Araucariaceae. These fungi lack specificity in their host association (are able to associate with a variety of plants) and, in practical terms, are common.

So far more than 50 species of fungi living on or near the trees have been identified, at least one third of which are new to science. Intriguingly, one of the species, Pestalotiopsis, that has been isolated from the foliage produces taxol, a cancer-controlling drug, though not in quantities useful for medicine.

Our tests have shown that, like many other Australian plant species, Wollemi Pines are susceptible to two common and easily transmitted pathogens: Phytophthora cinnamomi and Botryosphaeria sp. It is important to ensure that plants are cultivated in the absence of these pathogens and that the plants are not subjected to stress conditions that could predispose them to these diseases.

More importantly in the wild it is essential that hygiene measures already in place at the Wollemi Pine sites continue to be enforced, to ensure none of these fungal pathogens are accidentally transferred to the adult populations.

Researchers

Diseased Wollemi Pine cutting
Wollemi Pine cutting inoculated with Botryosphaeria sp., an airborne fungus that can kill stressed young plants within three weeks of infection.

Phytophthora cinnamomi
Juvenile Wollemi Pine inoculated with Phytophthora cinnamomi, showing disease symptoms from the stem base to the bases of most leaves. The plant died within three weeks of infection.