Clover growth in Mars-like soils boosted by bacterial symbiosis
Benefits of nitrogen-fixing bacteria could aid efforts towards farming
soils on Mars

Date:
September 29, 2021
Source:
PLOS
Summary:
Clover plants grown in Mars-like soils experience significantly
more growth when inoculated with symbiotic nitrogen-fixing bacteria
than when left uninoculated, researchers report.



FULL STORY ========================================================================== Clover plants grown in Mars-like soils experience significantly more
growth when inoculated with symbiotic nitrogen-fixing bacteria than when
left uninoculated. Franklin Harris of Colorado State University, U.S.,
and colleagues present these findings in the open-access journalPLOS
ONE on September 29, 2021.


==========================================================================
As Earth's population grows, researchers are studying the possibility of farming Martian soils, or "regolith." However, regolith is lacking in some essential plant nutrients, including certain nitrogen-containing molecules
that plants require to live. Therefore, agriculture on Mars will require strategies to increase the amount of these nitrogen compounds in regolith.

Harris and colleagues hypothesize that bacteria could play a
cost-effective role in making Martian soils more fertile. On Earth,
bacteria in soils help convert or "fix" atmospheric nitrogen into
the molecules that plants need. Some of these microbes have symbiotic relationships with plants, in which they fix nitrogen within nodules
found on plant roots.

To explore a possible role for symbiotic nitrogen-fixing bacteria in astroagriculture, the researchers grew clover in man-made regolith that
closely matches that of Mars. They inoculated some of the plants with
the microbe Sinorhizobium meliloti, which is commonly found in clover
root nodules on Earth. Previous research had shown that clover can be
grown in regolith, but had not explored inoculation with nitrogen- fixers.

The researchers found that the inoculated clover experienced 75% more
root and shoot growth compared to the uninoculated clover. However, the regolith surrounding the inoculated plants showed no signs of elevated
NH4 -- an essential nitrogen-containing molecule for plants -- compared
to the regolith surrounding uninoculated plants.

These findings suggest that the symbiotic microbes boosted clover growth,
but did not result in excess production of nitrogen compounds that other
plants growing nearby could hypothetically use. The researchers also grew
some clover in potting soil and noted certain differences in the symbiotic relationship when comparing the plants grown in regolith versus soil.

These findings suggest the possibility that symbiosis between plants and nitrogen-fixing bacteria could aid agriculture on Mars. Future research
could continue to explore such relationships with other crops and address issues with plant toxicity in regolith.

The authors add: "This study shows that nodule forming bacteria
Sinorhizobium meliloti has been shown to nodulate in Martian regolith, significantly enhancing growth of clover (Melilotus officinalis) in a greenhouse assay. This work increases our understanding of how plant and microbe interactions will help aid efforts to terraform regolith on Mars." ========================================================================== Story Source: Materials provided by PLOS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Franklin Harris, John Dobbs, David Atkins, James A. Ippolito,
Jane E.

Stewart. Soil fertility interactions with Sinorhizobium-legume
symbiosis in a simulated Martian regolith; effects on nitrogen
content and plant health. PLOS ONE, 2021; 16 (9): e0257053 DOI:
10.1371/ journal.pone.0257053 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210929142804.htm

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