Two soil microorganisms can work together to help plants obtain iron. Researchers studied fungi, Trichoderma brevicompactum TB2, bacteria, Brilliant pseudo PSE180.
Iron is essential for photosynthesis and many cellular reactions. However, it can be present in large quantities without being usable by the roots. In calcareous soils, the high pH keeps some of this iron in poorly soluble forms.
Iron is essential for photosynthesis.
Illustration: Pixabay.
The researchers first added the TB2 fungus to two types of soil. The first soils retained natural microorganisms. The second soil was sterilized to remove most of it. The goal of this comparison was to determine whether the fungus works alone or with the help of other microbes naturally present in the soil.
In natural soil, TB2 further improved plant growth and iron content. Its effect diminishes in sterile soil. This result showed that the fungus may have benefited from the presence of certain bacteria living around the roots.
The team then analyzed the bacterial DNA found in this region, called the rhizosphere. They looked for bacteria that became more abundant after adding the mushrooms. A genetic signature called ASV49 was particularly prominent in the treated samples.
The researchers isolated several soil bacteria to find the bacteria corresponding to ASV49. strain of Brilliant pseudonamed PSE180, showed a genetic match. They then cultured these bacteria with the mushrooms to check their compatibility. These tests showed no significant inhibition between the two organisms.
Finally, the plants received fungi alone, bacteria alone, or both. This formulation gave the best results in the growth and accumulation of iron under the conditions studied. The fungus appears to favor bacteria, which then helps release iron around the roots.
These experiments were performed using specific strains and in a controlled environment. Researchers still need to verify its effectiveness on other plants, in different soils, and over several seasons. They will also need to measure the stability of this collaboration in response to changes in temperature, humidity and fertilization.
