Agriculture around the world is under double stress today. On the one hand, the growing population of the Earth needs more high-quality and safe food, on the other hand, global climate change leads to more frequent droughts, salinization of soils and outbreaks of aggressive pathogens. To protect the most important crops, biologists at Tomsk State University, together with their Chinese partners, are developing a fundamentally new method of plant protection based on the use of exclusively natural compounds. The ‘vaccination’ against stress factors will combine plant sugars (oligosaccharides) and powerful phytohormones – brassinosteroids.

– Traditionally, synthetic fertilizers and pesticides are used in agriculture to protect plants and increase yields, – says Marina Efimova, project manager, associate professor of the Department of Plant Physiology, Biotechnology and Bioinformatics (TSU Biological Institute). – However, this path leads to soil depletion and pollution of water bodies, and most importantly, the resulting products may be unsafe for consumers.

Biologists from Russia and China are creating an alternative approach that eliminates the use of harsh chemistry and is eco-friendly. Its aim is to activate the immunity of plants using special biocomposites. The basis of this synergistic pair is brassinosteroids and levan-derived oligosaccharides (LOS).

– Unlike animals that can run away from danger or change their habitat in search of food, plants exist within an attached mode of life. They are forced to live in the plot of land on which they grow, and utilize the minimum of resources, – explains the main project executor, senior researcher at the Higher Engineering School of Agrobiotechnology at TSU Lilia Kolomeichuk. – It is interesting that whatever stresses the plant faces, be it soil pollution with heavy metals, salinity, drought or frost, in 99% of cases damage at the cellular level will be caused by severe water deficiency.

For example, during freezing, free water inside the plant cell begins to crystallize. Ice crystals expand, tearing cell membranes from the inside. When thawed, damaged cells lose moisture, and the plant dies from dehydration.

It is possible to prevent damage and death of plantings if plant immunity is activated in advance. To do this, scientists conduct their priming. This is a kind of training that prepares the body for stress. Moreover, the protective response will work regardless of what exactly the plant will face – drought, cold or disease. Under normal conditions, the plant does not consume excess energy, but when adverse factors occur, it instantly activates protection.

– The priming that we carry out is the treatment of plants with biocompositions from brassinosteroids and levans, explains Marina Efimova. – Levan molecules (LOS) have a unique ability to attract and retain moisture. Located on the outside of cell membranes, they act like a sponge, creating a protective water barrier around the cell. This prevents water from randomly crystallizing when frozen and protects tissues from tearing.

Brassinosteroids give the cell a command for the synthesis of special chaperone proteins and antioxidant enzymes. They neutralize toxic compounds (oxidative stress) that are formed in tissues under any adverse factors.

Previously, TSU scientists have already tested the capabilities of two types of phytohormones – 24-epibrassinolide and 24-epicasterone. Biologists were the first in Russia to use them to protect the most popular crops (barley, rapeseed, wheat and potatoes) from drought and heavy metals.

Chinese scientists, in turn, are world leaders in LOS synthesis. At the moment, they managed to solve the problem of poor solubility of levans. Instead of giant natural levan chains, which include more than 400 thousand monomers, Chinese specialists learned how to synthesize ultra-short compounds – from only 10-12 links. Such short LOS are perfectly soluble in water, which allows them to be effectively used for spraying and watering plants.

The task of the new Russian-Chinese project is not just to mix phytohormones and levans, but to find their ideal proportion, concentration and develop optimal processing technologies for different types of crops. In the course of joint experiments in Russia and China, scientists will test the effectiveness of biocomposites in soil salinization, drought, temperature drops, exposure to pathogens and select the most effective dosages and treatment methods for each crop.

The study of the synergistic effect of these two groups of natural bioregulators opens up new opportunities for creating advanced domestic agricultural technologies. This will allow agricultural producers to get a stable harvest in any weather conditions and in different territories, including risky farming zones such as Siberia and the Far East.