Overview

Project Highlights:

  • We have discovered a previously unknown plant-fungus symbiosis with global distribution
  • You will unravel the global diversity of the fungal symbionts involved, the factors which control their distribution, and the way in which the fungi interact with their host
  • The project will provide training in a wide range of modern molecular ecological analyses

Plant roots live in close association with diverse communities of microbes, including prokaryotes such as bacteria, and eukaryotes such as fungi, which together constitute the root ‘microbiome’. Root associated microbes interact with the plant in a myriad of ways; some act as symbionts which promote plant growth, while others are parasites which can have deleterious impacts on growth and development. As a result, understanding and harnessing interactions in the root zone (termed the ‘rhizosphere’) has enormous importance for ensuring food security.

Most plants form mutualistic mycorrhizal symbioses with fungi in which carbon fixed by photosynthesis is exchanged for nutrients, particularly N and P, from the fungus. Arbuscular mycorrhizas are the most widespread of these symbioses, and are found on herbaceous and woody plant species across many ecosystems across the planet. These mycorrhizas are associated with fungal hyphal entry into root cortical cells, in which structures called arbuscules are formed, in which resource exchange between the symbionts takes place (Fig 1). The mycelium of the fungal partner radiates into the soil surrounding the plant, assimilating nutrients, particularly P, which is transferred to the plant in exchange for sugars.
The fungi which form arbuscular mycorrhizas are obligate symbionts, so they cannot be grown in the absence of a host plant. Traditionally, arbuscular mycorrhizal fungi have been considered to come from the phylum Glomeromycota.

These fungi comprise diverse communities, with composition determined by a range of factors including plant species, soil properties and in agricultural systems, crop management.

However, it has been recognized that some fungi which produce arbuscules within plant roots have distinctive fine mycelium, and very small spores. The identity of these ‘Fine Root Endophyte (FRE)’ has been a long standing mystery. Recently, our UK- Australian collaboration, has shown that these fungi belong to the phylum Mucoromycotina, and are completely unrelated to the Glomeromycotan fungi. As such they represent a newly recognized symbiosis. Although we know that FRE are globally distributed and can be both diverse and abundant within ecosystems (Fig 2) we know almost nothing about the diversity and ecology of the fungi involved, or the way in which they interact with their host plant.

Arbuscules formed by a fine endophyte fungus in a clover root

Methodology

You will use a variety of molecular approaches to characterise FRE mucoromycotan fungus diversity and function. This will include DNA and RNA extraction and purification, PCR, sequencing using next generation platforms and bioinformatic analysis. In particular there will be scope to use ‘metatranscriptome’ approaches, in which mRNA is extracted, sequenced, and used to profile plant and fungal gene expression.

These approaches will be used in conjunction with samples from different ecosystems in both the UK and Australia. The samples will be used to build up a picture of the global diversity of FRE Mucoromycotan fungi, their distribution across habitats and local responses of diversity and function to factors such as soil management, season, and plant species.

There will be opportunities for a research placement in Perth (dependent on funding) to work with FRE plant cultures and to sample local habitats such as the Jarrah Forest

Training and Skills

CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes.

Timeline

Year 1: Analysis of fungal rhizosphere community assembly in samples from UK and Australian habitats using next generation sequence analysis. Community diversity, composition, and associations between Gomeromycotan and FRE Mucoromycotan fungi, will be determined.

Local scale analysis of fungal rhizosphere community dynamics (eg comparison of plant species within semi natural or agricultural landscapes).

Year 3: Functional interpretation of FRE Mucoromycotan-plant symbioses by studying plant growth responses and metatranscriptome analysis to investigate the symbiosis at the level of gene expression.

Partners and collaboration (including CASE)

This project would run alongside a large NERC-BBSRC programme grant funded as part of the Soil and Rhizosphere Interactions for Sustainable Agri-ecosystems programme providing opportunities to collaborate with a range of industrial, institute and academic stakeholders in the agricultural sector.

Further Details

Professor Gary Bending
School of Life Sciences,
University of Warwick,
Coventry, CV4 7AL
Email: gary.bending@warwick.ac.uk
Direct Line: 024 76575057