Mycorrhizal fungal community composition: host identity and ecosystem development
Last updated: 4 Feb, 2015
New Phytologist Editors’ Choice March 2015
Martínez-García, LB, Richardson, SJ, Tylianakis, JM, Peltzer, DA, Dickie, IA. 2015. Host identity is a dominant driver of mycorrhizal fungal community composition during ecosystem development. New Phytologist 205: 1565–1576.
When the new—soil-less—ground becomes available after glacier retraction or volcanic eruptions, organisms start to arrive and soil starts to develop through the complex interplay of biota and abiota. How the vegetation and physicochemical properties of soils change during this process (primary succession) is relatively well understood, however, knowledge about how plant-related microbes, so essential for soil formation and plant life, change during succession, is still very fragmentary. This is not because there is no interest. Rather, the strongest limitation is that there are few study systems on the Earth where natural succession can be investigated without confounding factors such as altitudinal and related climatic, or other changes, alongside the changing age of ecosystems. Franz Josef Glacier in New Zealand is one of the few such sites, having freshly deglaciated lands, progressing mid-successional and climax ecosystems and retrogressing habitats, spanning site ages from 5 to 120 000 years since deglaciation.
This paper by Martinez-Garcia and colleagues embarks on an exciting journey towards understanding how the assemblages of plant root associating arbuscular mycorrhizal (AM) fungi change during primary succession. They find that some AM fungi prevail during early succession, others are found in well-developed ecosystems and a third group of fungi can be found in the retrogressing ecosystems; some fungi occur throughout all stages. Major shifts, rather than incremental changes of the fungal communities, occur between the ecosystem stages. The identity of the plant host was demonstrated to be the major factor determining the suite of root-associating AM fungi.
Figure 2 from the paper (Martinez-Garcia et al.). Proportion of pyrosequencing operational taxonomic units (OTUs) along the Franz Josef soil chronosequence that have a significant response (P < 0.05) to ecosystem age: (a) linear or log-linear decreases (early OTUs), (b) quadratic (mature OTUs) and (c) linear or log-linear increases (retrogression OTUs). Model selection based on lowest Akaike Information Criterion (AIC) value.
This study is the first one to look at the AM fungal communities over such a long gradient of ecosystem development, and provides the very first data of AM fungi from retrogressive habitats. As an exemplary ground-breaking study, this paper opens more questions than it answers, indicative of the exciting discoveries ahead. What are the properties (traits) of AM fungi making them abundant in differently aged vegetation? What governs the AM fungal–plant-host relationships? Which AM fungi are needed to revegetate a barren ground or to restore a well-functioning self-sustaining mature ecosystem? These are just a few of the questions that will be tackled by the scientific community, thanks to this paper, with fresh rigour and inspiration.
Maarja Öpik, Editor New Phytologist
University of Tartu, Estonia
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Originally posted 4 February 2015