A project undertaken at Australian National University, and supervised by Prof Celeste Linde.
This project tackles a key unexplored aspect of molecular conservation biology of Australian orchids. Here we aim to identify genes that allow orchid mycorrhizal fungi to support orchid germination and growth. The vulnerability of orchids is partly because their growth and survival are tightly linked with colonisation by compatible orchid mycorrhizal fungi (OMF). It is essential to understand these interactions better because of the 670 plant species listed as endangered in Australia, 135 of those are orchids and many more are threatened (EPBC Act 1999). Furthermore, OMF differ in their essential macro- and micro-nutrients they provide to orchids, such that orchids with suboptimal OMF partners are nutritionally disadvantaged. The OMF specificity and varying nutrition present a conservation challenge, especially for germination of threatened orchids where the fungus is unknown or unavailable. We will investigate the molecular and genomic mechanisms of orchid-fungal interactions, with a focus on fungal recognition and nutrient exchange in a highly fungal-specific orchid species Chiloglottis trapeziformis, which only associates with one species of fungus, Tulasnella prima. First, we will utilise cutting edge sequence technology to analyse the genome of the orchid, before generating transcriptomes of adult and germinating orchid material. We will utilise a previously generated T. prima genome and C. trapeziformis transcriptomes to help disentangle genes involved in the interaction. Since fungal recognition is likely governed by the same mechanisms as plant-pathogen interactions, we will target “effector-like”, “defense like” and symbiosis marker genes to better understand the fungal interaction. To investigate nutrient exchange between the orchid and the fungus, all possible nutrient pathways or genes involved will be explored. Knowledge of the genes involved in the recognition step and nutrition will be the first step in determining requirements for orchid-fungal interactions in other orchid systems to inform future conservation of threatened species.