PhD Studentship: Understanding how beneficial soil bacteria promote plant growth. BBSRC SWBio DTP PhD studentship 2025 Entry

About:

The BBSRC-funded SWBio DTP involves a partnership of world-renown universities, research institutes and industry, based mainly across the South West and Wales.

This partnership has established international, national and regional scientific networks, and widely recognised research excellence and facilities.

We aim to provide you with outstanding interdisciplinary bioscience research training, underpinned by transformative technologies.

Project Description

Bacteria and other soil microorganisms are central to soil function and are essential for plant health. Microbes live on all plant surfaces, especially the root surfaces, called the rhizosphere, where they use nutrients released by the plant to grow. Certain bacteria in the rhizosphere microbiome are particularly important for plants as they promote plant growth through a range of mechanisms, including making nutrients available, producing hormones that stimulate growth and protecting against pathogens. When these beneficial bacteria are applied to crops as ‘biofertilisers’, they can promote plant yield, reducing the need for chemical fertilisers. However, the effects can be variable, because we do not know enough about how the introduced bacteria will interact with the host plants, and other elements of the soil environment. Hence, the aim of this project is to improve our understanding of plant-bacteria interactions, to inform more effective biofertiliser use.

Azospirillum sp are beneficial soil bacteria that have been used to promote the growth of several staple crops, including wheat and rice, for decades. There are several mechanisms that Azospirillum uses for growth promotion, mainly they produce hormones that stimulate root growth, enabling plants to acquire more nutrients. 

Further, this group of bacteria adapted to soil and plant association by acquiring traits from other soil bacteria on mobile genetic elements. As a result, there is a lot of genetic variation between strains, including in beneficial plant traits, making them an excellent model to study bacterial evolution and how it influences their ability to promote plant growth.

To understand which traits are most important for plant growth promotion, this project will combine bioinformatics, microbiology, molecular biology, plant experiments and microbial ecology and evolution theory.

In particular, this project will use a library of diverse Azospirillum strains and wheat growth experiments, and will involve:

1. bioinformatically predicting plant-associated genes,
2. carrying out molecular and microbiological assays for each trait as well as plant growth experiments,
3. linking bacterial genetics with the beneficial phenotypes using statistical analyses and
4. empirically testing candidate beneficial genes, by making genetic mutants and performing a range of experiments to understand their function and effect on bacterial fitness.

There is wide scope for flexibility, plus several exciting directions that the successful student could take this ambitious project, based on their interests. This project will make significant contributions to several fields, including plant-bacterial interactions, soil microbiology and microbial evolution and ecology.

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