Mycorrhizal fungi grow in and on plant roots helping extract nutrients from the soil. This is especially important for species such as Wollemi Pine that grow in shallow, nutrient-poor and highly acidic soils. These fungi 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.
Recent research analysed soil fungal and bacterial communities associated with wild Wollemi pine and its neighbouring co-dominant tree species, coachwood (Rigg et al. 2016). Environmental variation in the field contributed to the diversity of fungal, but not bacterial, communities within the roots of Wollemi Pine seedlings. Wollemi Pine recruited a distinct bacterial community in its roots.
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 species. 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.
Papers
- *Rigg J L, *Offord C A, Singh B K, Anderson I C, Clarke S & Powell J R, 2016 'Variation in soil microbial communities associated with critically endangered Wollemi Pine affects fungal, but not bacterial, assembly within seedling roots'. Pedobiologia 59 (1-2): 61-71.
- McGee P A, *Bullock S & *Summerell B A, 1999, ‘Structure of mycorrhizae of the Wollemi Pine (Wollemia nobilis) and related Araucariaceae’, Australian Journal of Botany, 47: 85-95.
* indicates staff and students of the Royal Botanic Gardens Sydney