How can we use beneficial bacterial to boost crop resilience against pests and disease? Dr Sharon Zytynska, BBSRC David Phillips Research Fellow at the Institute of Infection, Veterinary and Ecological Sciences tells us about how her group are tackling the global problem of sustainably feeding a growing population.
Population growth, climate change, pesticide resistance, environmental protection, public opinion – these are some of the many reasons why we need practical solutions for sustainable agriculture. Conventionally-managed cropping systems are highly productive but also highly damaging for biodiversity, both aboveground (insects, birds, mammals) and below-ground (bacteria, fungi, earthworms).
As part of my BBSRC David Phillips Fellowship at Liverpool, my research group is investigating beneficial soil bacteria for their potential in helping plants fight against aphids – small soft-bodied insects that feed on plant sap and transmit damaging plant viruses.
Monoculture crop systems can be viewed as an ‘all you can eat (and more)’ spread for insect pests, allowing quick population growth when uncontrolled. However, systems that minimise fertiliser or pesticide applications often produce less crop yield so sustainable agriculture solutions need to close that yield gap.
A promising direction for sustainable agriculture is to exploit and promote natural species (wildflowers, bacterial in soil) interactions, to increase pollinators and fight insect pests. Underneath the ground, plants actively recruit beneficial soil bacteria to their roots that increase plant growth by providing additional nutrients, or prime a plants’ inherent defence system making it more resistant to insect attack.
Our main bacteria species is Acidovorax radicis, which was isolated from wheat roots and found to increase root and shoot growth. We found it also made barley plants more resistant to aphids. In controlled studies we have shown aphid daily reproduction to be reduced by up to 50% and reduce aphid lifespan. Together these strongly reduce aphid numbers on inoculated plants. Current work is ongoing to understand how this happens and we are now transferring what we have found in the lab to larger-scale field trials with barley plants at Stockbridge Technology Centre.
The first hurdle was to grow enough bacteria in which we soak our seeds, and this all had to be done close enough to our planned drilling date for the bacteria to still be viable. I can happily say the seed was sown in the second week of April and we are already seeing good germination and growth.
Scaling this up has not been trivial, since we usually soak only a handful of seeds for lab experiments while for the field trial we were working with over 50 kg of seed. We will re-inoculate the soil once the plants are established using wet-matrix bacteria beads that encapsulate the bacteria, and can be easily spread across the field trial.
With a team of researchers and students, we will visit the field trials regularly to assess plant growth, the arrival and abundance of insect pests and their natural predators, as well as collect plant samples for molecular analysis, throughout the growing season.
At the end of the season we will measure plant yield and collect grain for quality analysis - It is going to be a busy but exciting summer!
Follow Sharon's research in ecology, plant-insect-microbe interactions and crop health on twitter at @SZytynska