The control of above-ground traits by plant hormones, including those traits important in crops such as height and tillering, is well established.
In the last 20 years, the role of plant hormones in the formation of beneficial interactions with nutrient-acquiring microbes has been emerging, with prominent roles for auxin, gibberellins, brassinosteroids, cytokinins and strigolactones.
Synthetic fertiliser has serious environmental consequences and there is now a focus on exploring more sustainable options for nutrient input, such as symbiosis.
Our aim is to discover new mechanisms of how plants establish, regulate and gain benefit from symbioses by integrating our understanding of core symbiotic pathways and hormone pathways.
This fundamental information is the basis for the connection of these plant mechanisms to genomes, which we need to understand to enable predictions.
More than 90% of land plants interact with nutrient-acquiring fungi in what is known as arbuscular mycorrhizal symbioses. Legumes, mainly, interact with nitrogen-fixing rhizobial bacteria in what is known as nodulation. These two symbioses share a deep evolutionary history, including important roles for plant hormones.
Plant hormones have also recently been shown to be an important cross-over point between roots and the unique root nodule organ.
Construction/curation of symbiotic and association hormone gene regulatory networks has not been attempted on any scale in symbioses research. We will explore alternative approaches to modelling gene regulatory networks with the aim of uncovering conserved and potentially divergent elements across species.
We seek to answer 2 questions:
How has modification of hormone signalling in crop breeding influenced the formation of root symbioses?
In major grain crops (wheat, barely, sorghum), semi-dwarf phenotypes typically arise from modification of the biosynthesis or signalling of plant hormones. Studies in model plants have implicated these hormones in the regulation of arbuscular mycorrhizal symbioses but the consequence for arbuscular mycorrhizal symbioses of modifying these hormones during breeding has not been assessed or understood.
Our characterisation of the symbioses phenotypes and performance of grain crops will be of immediate benefit to inform future breeding strategies.
Through simulation with sorghum, we will uncover key symbiotic genes that such hormone pathways intersect with, and examine their role in arbuscular mycorrhizal symbioses.
Are plant hormone signalling networks an important target for improving/optimising crop symbioses?
Beyond characterising the outcome that breeding and adaptation have had on symbiosis, we need to understand the interaction of plant hormones more broadly on arbuscular mycorrhizal and nodulation pathways. This includes the potential for plant hormones to modulate symbioses in response to nutrient and resource allocation.
To achieve this, we will examine genetic networks across species and perform targeted molecular and physiological studies.