LIPOSAM® - EXOPOLYSACCHARIDES OF MICROBIAL ORIGIN: A NEW APPROACH TO PLANT STRESS MANAGEMANT

Resistance to salinity

In plants, resistance to salinity depends on the ability to control the absorption of ions and maintain stable conditions within themselves. They distinguish between toxins and useful substances, for example, potassium ions and nitrates.

Bacterial exopolysaccharides (EPS) can bind cations and limit their uptake by plant root systems. This helps maintain the potassium/sodium balance and improves plant tolerance to salinity.

A 2005 study showed that co-inoculation of soybeans with exopolysaccharide (EPS)-producing bacteria Bradyrhizobium japonicum and Bacillus subtilis helped plants tolerate salinity through EPS-mediated limitation of sodium uptake.

A 2016 study showed positive effects of EPS on relieving salt stress. When using EPS, it was found that free sodium ions from the soil can be bound (even up to 200 mM NaCl), making them unavailable to soybean plants.

Therefore, the mechanisms of EPS action in soil are to protect the plant root system through the formation of a biofilm and increases its stability through the limited absorption of sodium ions. Chelating toxic ions makes them inaccessible to plant roots. This contributes to normal plant growth even with excessive salt load.

This effect can be especially relevant when you combine Liposam® together with herbicides. A trial, which was conducted at the Skvirsk research station of organic production of the Institute of Agroecology and Nature Management of the National Academy of Sciences of Ukraine  confirms the positive effect of using a combination of EPS  Liposam and the herbicide Primextra TZ Gold (4 l/ha) on the sunflower and corn yields.

Exopolysaccharides and drought

Exopolysaccharides (EPS) are one of the most important components of biofilms. They are involved in intercellular aggregation, which is a crucial factor for fixing and "sticking" bacteria to plant roots. This helps to increase the ratio of soil to plant root tissue, as well as soil porosity. Porous soil holds water better, which helps plants absorb water and nutrients.

EPS can also be adsorbed on soil particles and solidify them. This occurs due to the formation of cation bridges, hydrogen bonds, Van der Waals forces and anion adsorption mechanisms. This leads to an increase in the stability of soil aggregates, soil moisture and plant productivity.

R&D researchers at the Institute of Applied Biotechnology found that Liposam® increased the moisture-holding capacity of typical black soil and reduced the migration of organic, mineral, and organo-mineral components beyond the 0-50 cm layer by 25-41% compared to the control.

In the rhizosphere, the soil zone that is 0.5 to 4 mm from the plant root, exopolysaccharides (EPS) act as water reservoirs and water conductors to the plant roots when there is a moisture deficit.

The direct effect of EPS on increasing plant resistance to drought is also interesting. For example, the results of research in 2014 proved that the activity of antioxidant enzymes was higher on corn plants inoculated with bacteria. Scientists of the Institute of Physiology and Plant Genetics of the National Academy of Sciences of Ukraine conducted a study of the effectiveness of a 0.1% aqueous solution of Liposam® in the agrocenosis of winter wheat.

Just 5 days after using Liposam®, the rate of photosynthesis increased by 10%.

At research stations in the conditions of a dry summer, Liposam® worked almost at the level of the best anti-stress agents, although it is primarily an adhesive adjuvant. Liposam® has been shown to be effective in increasing sunflower yields by 15% in the absence of rain for 90 days.

EPSs regulate the response of plants to water deficit, which increases the time required for plants to adapt their metabolism to drought stress.

So, today the biological adhesive Liposam® is used in both integrated and organic agriculture in 12 countries of the world. The high compatibility of Liposam® with various active substances, such as herbicides, insecticides, fungicides, trace elements and desiccants, leads to an increase in efficiency of up to 15%.

Exopolysaccharides and extreme temperatures

In 2012, scientists investigated the protective functions of the EPS biofilm formed around the roots, which alleviates stress from high temperatures, improves water retentionand alleviates the effects of heat shock in the plant.

In 2019, scientists found that EPS biofilm can increase the resistance of wheat seedlings to stress associated with low temperatures. This biofilm secretes specific metabolites that protect both bacteria and plants and facilitate root colonization. Under the influence of cold stress, plants experience dehydration, osmotic imbalance, and changes in the sodium/potassium ratio in the roots. This negatively affects the absorption of nutrients. However, EPS can chelate sodium ions and thus protect plants from cold-induced dehydration.

The picture shows the mechanisms of alleviating abiotic stress in plants with the help of microbial exopolysaccharides.

Another extraordinary advantage of the complex biological adhesive Liposam is the unique property of preventing the dripping of foliar fertilizers, stimulants, and plant protection agents from the surface of the leaves. Therefore, it has a favorable effect on the recovery of plants after stress.

During model experiments conducted by employees of the Institute of Applied Biotechnology, the percentage of fixation of the active substance due to Liposam® increased. After simulating rain, the increase in fixation occurred on the leaves of various crops, ranging from 1.4 to 6.0 times.