Unravelling the distribution, structure and function of diverse plant-fungal symbioses

Among the Earth’s most important symbiotic relationships are the associations between mycorrhiza-forming soil fungi and plant roots, where fungal acquired nutrients are exchanged for photosynthetically fixed plant carbon. A distinctive group of mycorrhizal fungi known as Mucoromycotina Fine Root Endophytes (MFRE) have been molecularly identified across land plants over the last decade and have been shown to form nutritional mutualisms with liverworts and the vascular plant Lycopodiella inundata. As interest grows in the potential application of MFRE in agriculture as biofertilisers, it is imperative that we learn more about the ecology and function of these fungi in vascular plants. This thesis is concerned with addressing these knowledge gaps. A third of my investigations were dedicated to evaluating and improving methods for the molecular detection of MFRE in plant roots and for the enrichment of vascular plants with MFRE. I used a cloning with Sanger sequencing approach to detect fungal symbionts in plant specimens from New Zealand and the UK. For the first time, I molecularly confirmed MFRE in the roots of white clover, wheat, barley and the strawberry plant, obtaining 25 new MFRE DNA sequences. I set up two isotope tracing pot experiments to compare fungal transfer of nutrients in plants colonised by two different fungal communities, an MFRE-enriched one and one with only arbuscular mycorrhizal fungi (AMF), under low nutrient conditions and in the presence of other soil microorganisms. I found that co-colonisation of plant roots by MFRE and AMF does not impair the transfer of fungal acquired phosphorus to Trifolium repens and fungal acquired nitrogen from organic and inorganic sources to Holcus lanatus. However, the presence of MFRE stunted plant architecture in both experiments, suggesting that MFRE symbioses occur on a parasitism-mutualism continuum. Bearing these findings in mind, I make recommendations for further MFRE research

Molecular Evidence of Mucoromycotina “Fine Root Endophyte” Fungi in Agricultural Crops

Over 85% of land plants engage in symbiotic relationships with mycorrhiza-forming soil fungi that colonise their roots. These mycorrhizal symbioses, which involve the exchange of fungal-acquired nutrients and water for photosynthetically fixed plant carbon, are considered a promising nature-based solution to making agricultural practices more sustainable. In order to implement the widespread use of mycorrhizal fungi in agriculture, a more complete awareness of mycorrhizal fungal diversity and range of plant hosts is needed. Mucoromycotina Fine Root Endophytes (MFRE) are a group of mycorrhiza-forming fungi that have recently been shown to be phylogenetically and functionally distinct from arbuscular mycorrhizal fungi (AMF). Here, we provide the first molecular evidence of MFRE colonisation of winter wheat, winter barley, spring wheat and strawberry roots. Fungal symbionts were identified from partial DNA sequences of the 18S ribosomal RNA gene, obtained through a workflow involving molecular cloning and Sanger sequencing. Our findings shed light on the true distribution of plant-MFRE associations and give rise to new questions regarding their functional significance within agricultural plants

Enhancing climate change resilience in agricultural crops

Climate change threatens global food and nutritional security through negative effects on crop growth and agricultural productivity. Many countries have adopted ambitious climate change mitigation and adaptation targets that will exacerbate the problem, as they require significant changes in current agri-food systems. In this review, we provide a roadmap for improved crop production that encompasses the effective transfer of current knowledge into plant breeding and crop management strategies that will underpin sustainable agriculture intensification and climate resilience. We identify the main problem areas and highlight outstanding questions and potential solutions that can be applied to mitigate the impacts of climate change on crop growth and productivity. Although translation of scientific advances into crop production lags far behind current scientific knowledge and technology, we consider that a holistic approach, combining disciplines in collaborative efforts, can drive better connections between research, policy, and the needs of society