Newly discovered plant gene could boost phosphorus intake

Date:
June 16, 2020
Source:
University of Copenhagen
Summary:
Researchers have discovered an important gene in plants that could
help agricultural crops collaborate better with underground fungi
-- providing them with wider root networks and helping them to
absorb phosphorus. The discovery has the potential to increase
agricultural efficiency and benefit the environment.



FULL STORY ========================================================================== Researchers from the University of Copenhagen have discovered an important
gene in plants that could help agricultural crops collaborate better
with underground fungi -- providing them with wider root networks and
helping them to absorb phosphorus. The discovery has the potential to
increase agricultural efficiency and benefit the environment.


==========================================================================
It is estimated that about 70 percent of phosphorus fertilizer used in
Danish agriculture accumulates in soil, whereas only 30 percent of it
reaches plants.

Quid pro quo -- that's how one might describe the "food community" that
the majority of plants have with mycorrhizal fungi. Plants allow fungi to
live among their roots, while feeding them fat and sugar. And in return,
fungi use their far-reaching hypha (filamentous branches) to capture vital
soil nutrients for plants, including the important mineral phosphorus.

Now, researchers at the University of Copenhagen's Department of Plant
and Environmental Sciences have discovered an extraordinary plant gene,
the CLE53 gene, which regulates cooperation between fungi and plants. The
gene is central to a mechanism that controls how receptive plants are to working with mycorrhizal fungi. Down the road, this newfound knowledge
could serve to deliver better harvests and reduced fertiliser use.

"Similar genes are found in all plants -- including agricultural
crops. So, by mutating or turning off the CLE53 gene in a crop plant,
it is more likely for a plant to become symbiotically involved with a
fungus. In doing so, it becomes possible to reduce the need for phosphorus fertilizers, as plants improve at absorbing preexistent phosphorus from
soil," explains Assistant Professor Thomas Christian de Bang of the
Department of Plant and Environmental Sciences.

The research has been published in the Journal of Experimental Botany
Seventy percent of phosphorus fertilization does not reach plants


========================================================================== Phosphorus is vital for all plants. However, the problem with phosphorus
use in agriculture is that more of it is applied for fertilisation
than can be absorbed by crops. It is estimated that about 70 percent of phosphorus fertilizer used in Danish agriculture accumulates in soil,
whereas only 30 percent of it reaches plants. With rain, there is an ever present risk that some of the accumulated phosphorus will be discharged
into streams, lakes and the sea.

Paradoxically, researchers have observed that when phosphorus levels
in soil are high, plants are less likely to collaborate with fungi,
meaning that they become worse at absorbing nutrients.

"Through a range of experiments, we have demonstrated that a plant
does not produce the CLE53 gene if it lacks phosphorus. However,
when the phosphorus levels in a plant are high, or if the plant is
already symbiotically involved with a fungus, then the level of CLE53 increases. Our study demonstrates that CLE53 has a negative effect on
a plant's ability to enter into symbiosis with a fungus, and thereby
absorb phosphorus most effectively," says Thomas Christian de Bang.

Requires CRISPR approval The genomic editing of plants is legal in a
number of non-EU countries -- e.g., China, the US, Switzerland and the
UK. However, within the EU, there is no general acceptance of gene-editing methods, such as CRISPR, to alter plants and foodstuffs.



========================================================================== Therefore, the researchers' discovery has, for the time being, a poorer
chance of being used in Denmark and the rest of the EU.

"One can use the technology in other parts of the world, and getting
started would be relatively straightforward. My guess is that within five years, plants will be tested and refined in such a way that they become
more symbiotically involved with fungi and absorb more phosphorus. Here
in Denmark and throughout the EU, an acceptance is required for gene
editing and an amended approach to approval procedures for these types
of plants," says Thomas Christian de Bang.

Facts: 90% of all plants engage in symbiotic relationships with
mycorrhizal fungi, which popularly said, extend the root networks of
plants, thus helping them to obtain enough phosphorus, water and other nutrients.

In order to benefit from the ability of mycorrhizal fungi to extract
phosphorus from soil, a plant must feed it with fat and sugar. To avoid spending too much energy on the sponge, if for example, it is experiencing
high phosphorus levels or has already been colonised by a fungus, the
plant may switch off symbiosis.

It is estimated that Danish farms fertilise with roughly 30 kilos of
phosphorus per hectare of land.

Of this, roughly 30 percent makes its way to crops, while the remaining
70 percent binds to soil.

With rain, some of this accumulated phosphorus is flushed away via
surface runoff, into nearby streams, lakes and the sea. This increases
algae growth and can kill both plants and wildlife.

Phosphorus is a finite natural resource, one that is expected to
eventually be depleted.

The research is funded by the Novo Nordisk Foundation and the University
of Copenhagen Previous research has shown that a similar mechanism exists
for symbiosis between legumes and rhizobium bacteria. This involved
a CLE gene as well, albeit a different one than the researchers have
now discovered.


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


========================================================================== Journal Reference:
1. Thomas C de Bang, Patrick X Zhao, Xinbin Dai, Kirankumar S Mysore,
Jiangqi Wen, Gonzalo Sancho Blanco, Katrine Gram Landerslev,
Clarissa Boschiero, Magda Karlo. The CLE53-SUNN genetic pathway
negatively regulates arbuscular mycorrhiza root colonization in
Medicago truncatula.

Journal of Experimental Botany, 2020; DOI: 10.1093/jxb/eraa193 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200616135816.htm

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