Smart soil bugs offer farmers an ecofriendly route to controlling crop diseases

Date:
January 18, 2022
Source:
John Innes Centre
Summary:
An innovative method of controlling a range of damaging crop
diseases using native, beneficial soil bacteria has emerged from
a research- industry collaboration.



FULL STORY ==========================================================================
An innovative method of controlling a range of damaging crop
diseases using native, beneficial soil bacteria has emerged from a research-industry collaboration.


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The agri-tech innovation hopes to give farmers a way to reduce the cost
and environmental damage caused by the chemical treatments currently in
use to control crop diseases.

The John Innes Centre team isolated and tested hundreds of strains of Pseudomonasbacteria from the soil of a commercial potato field, and then sequenced the genomes of 69 of these strains.

By comparing the genomes of those strains shown to suppress pathogen
activity with those that did not, the team were able to identify a key mechanism in some of the strains that protected the potato crop from
harmful disease-causing bacteria.

Then using a combination of chemistry, genetics and plant infection
experiments they showed that the production of small molecules called
cyclic lipopeptides is important to the control of potato scab, a
bacterial disease that causes major losses to potato harvests.

These small molecules have an antibacterial effect on the pathogenic
bacteria that cause potato scab, and they help the protective Pseudomonas
move around and colonise the plant roots.



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The experiments also showed that irrigation causes substantial changes
to the genetically diverse Pseudomonaspopulation in the soil.

First author of the study Dr Alba Pacheco-Moreno said, "By identifying
and validating mechanisms of potato pathogen suppression we hope that
our study will accelerate the development of biological control agents
to reduce the application of chemical treatments which are ecologically damaging.

"The approach we describe should be applicable to a wide range of plant diseases because it is based on understanding the mechanisms of action
that are important for biological control agents," she added.

The study, which appears ineLife, proposes a method by which researchers
can screen the microbiome of virtually any crop site, and take into
account varying soil, agronomic and environmental conditions.

By exploiting advances in high-speed genetic sequencing, the method can
screen the soil microbiome for therapeutic bacteria and work out which molecules are being producedto suppress pathogenic bacteria.



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They can also show how these beneficial bugs are affected by agronomic
factors such as soil type and irrigation.

The next step for the new approach is to put the beneficial bugs back
into the same field in greater numbers or in cocktails of mixed strains
as a soil microbiome boosting treatment.

Dr Jacob Malone, Group Leader at the John Innes centre and
co-corresponding author of the study explains the benefits, "The massive advantage of this approach is that we are using bacterial strains
that are taken from the environment and put back in the same specific biological context in larger numbers so there is no ecological damage." Potential methods to apply the microbiome boosters include applying the bacterial cocktails as seed coatings, as a spray or via drip irrigation.

Dr Andrew Truman, Group Leader at the John Innes Centre, and corresponding author of the study tells us about the long-term vision for this method,
"In the future it's not the molecule produced by the bacteria that we
would use, it would be the Pseudomonas strain itself. It offers a more sustainable route - - we know these bacteria colonize the soil where
potatoes grow, and they provide protection to the crop. Using a bacterium,
you can easily grow and formulate it in an appropriate way and apply it
to the field, and it is much greener than using a synthetic chemical."
Plant diseases are an agricultural problem that leads to major losses of
crops, such as potatoes. Important potato pathogens include Streptomyces scabies, a bacterial pathogen that causes potato scab, and Phytophthora infestans, an oomycete pathogen that causes potato blight, which was a
major cause of the Great Famine in Ireland.

Pseudomonas bacteria are commonly associated with plants and have been
widely studied as biological control agents, as they secrete natural
products which promote plant growth and suppress pathogens. However,
their use in the past has been hampered by inconsistency.

Previous studies on the suppression of potato scab have indicated
a potential biocontrol role for Pseudomonas.However, progress was
hampered by a lack of mechanistic knowledge. It was also widely known
that irrigation can suppress Streptomyces scabies infection and now
this study suggests that this is because of the effect that water has
on microbial populations.

========================================================================== Story Source: Materials provided by John_Innes_Centre. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Francesca L Stefanato, Alba Pacheco-Moreno, Jonathan J Ford,
Christine
Trippel, Simon Uszkoreit, Laura Ferrafiat, Lucia Grenga, Ruth
Dickens, Nathan Kelly, Alexander DH Kingdon, Liana Ambrosetti,
Sergey A Nepogodiev, Kim C Findlay, Jitender Cheema, Martin
Trick, Govind Chandra, Graham Tomalin, Jacob G Malone, Andrew
W Truman. Pan-genome analysis identifies intersecting roles
for Pseudomonas specialized metabolites in potato pathogen
inhibition. eLife, 2021; 10 DOI: 10.7554/eLife.71900 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220118104114.htm

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