The longer we study ecosystems, the more we realise there are many organisms living together with intimate connections. You don’t get much more intimate than the relationship between plants and their symbiotic partners called ‘endophytes’.
The name describes where these fungi live: endo = inside and phyte = plant. We also have intimate relationships with other organisms like the microbiome in our stomachs that helps us digest food.
By definition, fungal endophytes are fungi, which inhabit the leaves, stems, bark and roots of plants without causing disease symptoms. Some of these may be latent pathogens but generally the relationship is beneficial to the host plant.
Endophytes in grasses have been the most widely researched because of commercial /agricultural implications. However, this article will focus on the non-grass endophytes, though their stories are similar and equally amazing.
Endophytes remain hidden from human sight when we look at ecosystems, as they are living and working entirely within the tissues of their host plants. Molecular (DNA) techniques are giving us insights into some of the amazing diversity of endophytes that live inside rainforest plants in Southeast Queensland.
Up to 20 different species of endophyte were found in the leaves of one plant (the humble Wombat Berry, Eustrephus latifolius), in a study by Mapperson & Dearnaley, 2014. Tropical rainforests have even greater endophyte diversity.
Some of the benefits for plants that host endophytes include:
- Improved resistance to herbivores, by production of chemicals that decrease palatability of leaves and stems.
- Improved ability to withstand extreme temperatures and drought.
- Increased tolerance to heavy metals.
- Improved salt tolerance in some plants.
So the community of endophytes found in the tissues of their host plant, live together for years with no need to reproduce as they are getting everything they need to survive (food and water). It is only when their host plant senesces or dies that the endophytes appear to revert to a decomposer lifestyle and start recycling their host plant. At this stage they produce fruit bodies and undergo sexual reproduction.
Many endophytes are in the phylum Ascomycetes, which often produce fruit bodies that are shaped like discs or cups. Phillipsia subpurpurea is one of these local endophytes with large burgundy coloured centres and white undersides found on rotten logs in local rainforests. Fruiting down near the ground allows the spores to be dispersed where there are young rainforest plants that the endophytes can partner with. If these young trees get the opportunity to fill a gap and grow up and join the canopy they will grow with their endophyte partners already inside them to help them live.
Mapperson RR & Dearnaley JDW (2014)
Molecular taxonomy of Australian endophytic Pezizales. In: 2014 Scientific Meeting of the Australasian Mycological Society, 21-23 April 2014, Brisbane.
Rodriguez RJ, White Jr JF, Arnold AE & Redman RS (2009) Fungal endophytes: diversity and functional roles. New Phytologist, 182(2), pp.314-330.
Article by Sapphire McMullan-Fisher (mycologist) and Frances Guard (Land for Wildlife member)
Co-authors of Fungi of the Sunshine Coast and Mushrooms of the Sunshine Coast
produced by the Queensland Mycological Society (reviewed pg 16).
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