permaculture

[Lawrence London <lfljvenaura@gmail.com>]

https://phys.org/news/2019-05-art-microbial-maintenance.html

May 9, 2019
Plants and the art of microbial maintenance

by John Innes Centre <http://www.jic.ac.uk>
The plant as sculptor. Credit: Phil Robinson

It's been known for centuries that plants produce a diverse array of
medically-valuable chemicals in their roots.

The benefits for human health are clear, but it's been less apparent how
and why plants expend 20 percent of their energy building these exotic
chemicals. Is it for defence? Is it waste? What is it for?

A joint study from the John Innes Centre and the Chinese Academy of
Sciences has shed new light on this fundamental question of plant
specialised metabolism.

Appearing in the journal *Science*, the study reveals that plants use their
root <https://phys.org/tags/root/>-derived chemicals to muster and maintain
communities of microbes. It suggests that across the plant kingdom
<https://phys.org/tags/plant+kingdom/> diverse plant chemistry may provide
a basis for communication that enables the sculpting of microbial
communities tailored to the specific needs of the host plant, be that a
common weed or major crops such as rice or wheat.

The findings provide researchers with a gateway to engineering plant root
microbiota in a range of major crops.

"This question has fascinated people for hundreds of years and we've found
this chemistry enables plants to direct the assembly and maintenance of
microbial communities in and around the roots," says Professor Anne Osbourn
of the John Innes Centre, a co-author of the study.

"We assume that the plant is shaping the root microbiota for its own
benefit. If we can understand what the plant is doing and what kind of
microbes are responding to it and what the benefits are then we may be able
to use that knowledge to design improved crops or to engineer the root
microbiome for enhanced productivity and sustainability and to move away
from fertilizers and pesticides," adds Professor Osbourn.

In this study the team uncovered a metabolic network
<https://phys.org/tags/metabolic+network/> expressed in the roots of the
well-known model plant *Arabidopsis thaliana*. This network, organised
primarily around gene clusters, can make over 50 previously undescribed
molecules belonging to a diverse family of plant natural products
<https://phys.org/tags/natural+products/> called Triterpenes.

The researchers generated plants altered in the production of these
root-derived chemicals and working with Professor Yang Bai of the Chinese
Academy of Sciences grew these plants in natural soil from a farm in
Beijing.

The results showed clear differences in the types of microbial communities
that these plants assembled compared with the wild plants
<https://phys.org/tags/plants/>.

In further experiments the group synthesized many of these newly-discovered
chemicals and tested their effect on communities of cultured microbes in a
laboratory re-enactment of plant-microbial interactions in the soil.

"Using this approach, we can see that very small differences in chemical
<https://phys.org/tags/chemical/> structures can have profound effects on
whether a particular molecule will inhibit or promote the growth of a
particular bacteria. Taken together we can clearly see that very subtle,
selective modulation of microbes by this cocktail of chemicals," says first
author of the paper Dr. Ancheng Huang.

Comparisons with root bacterial profiles in rice and wheat that do not make
these *Arabidopsis* triterpenes demonstrated that these genetic networks
were modulating bacteria towards the assembly of an Arabidopsis-specific
root microbiota.

The next steps for the researchers is to explore further the benefits of
this sculpting of the microbial community for the plant and observe other
influences on plant chemistry such as nutrient limitation and pathogen
challenge.

The full study "A specialized metabolic network selectively modulates
*Arabidopsis* root microbiota," appears in *Science*.

Plants rely on their resident bacteria to protect them from harmful microbes
<https://phys.org/news/2018-11-resident-bacteria-microbes.html>
------------------------------
*More information:* A.C. Huang el al., "A specialized metabolic network
selectively modulates Arabidopsis root microbiota," *Science* (2019).
science.sciencemag.org/cgi/doi
… 1126/science.aau6389
<https://science.sciencemag.org/cgi/doi/10.1126/science.aau6389>

Provided by:

The John Innes Centre (JIC) located in Norwich, Norfolk, England is an
independent centre for research and training in plant and microbial
science. It is a registered charity (No 223852) grant-aided by the
Biotechnology and Biological Sciences Research Council (BBSRC) and is a
member of the Norwich Research Park. The John Innes Horticultural
Institution was founded in 1910 at Merton Park, Surrey (now London Borough
of Merton), with funds bequeathed by John Innes, a merchant and
philanthropist. The Institution occupied Innes's former estate at Merton
Park until 1945 when it moved to Bayfordbury, Hertfordshire. It moved to
its present site in 1967. John Innes Compost was developed by the
institution in the 1930s. In the 1980s, the administration of the John
Innes Institute was combined with that of the Plant Breeding Institute and
the Nitrogen Fixation Laboratory. In 1994, following the relocation of the
operations of other two organisations to the Norwich site, the three were
merged as the John Innes Centre.
Websitehttp://www.jic.ac.ukWikipedia
http://en.wikipedia.org/wiki/John_Innes_Centre

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