Nematodes – small root parasite worms – are not in the end of the list of numerous and various plant pests. They are very difficult to fight with. Researchers from RAS Parasitology Institute showed that plant tolerance towards the pests increases when plant seeds are treated with water-soluble chitosan.
 

Southern gall eelworm lives in open ground and in greenhouses and infests mainly tomatoes and cucumbers. Eelworms cause tumor – gall – formation on the roots of a host plant and settle there. They live on host plant’s blood. Females are those who blight. They lay eggs, which generate larvae, which get into soil and infest adjacent plants. Generation after the generation, under the favourable conditions gall eelworms spread so quickly that they can kill almost half crop. In response to the damage plants start to defend themselves – they produce specific agents, that enhance their parasite resistance, but often it’s too late, the plant is already heavily infested. The research showed that plant’s protective response could be accelerated, if the plant was treated with chitin, chitosan and its derivatives, but the mechanism of the process remained unclear. Moscow scientists decided to find out the mechanism of chitosan influence on plant-eelworm relations.
 

Let us remind you that chitosan is a native biopolymer, which is a cover constituent of insects, crustacean and some worms, including nematodes. After a specific treatment it becomes water-soluble. The scientists have studied chitosan influence on tomato resistance against gall eelworms. For this purpose the scientists treated tomato seeds with the solution with various concentrations of chitosan for two hours, and then the plants were infested with eelworms. The seeds of control group were soaked in pure water before planting.
 

Chitosan has proven to be effective in 100 mkg/ml concentration. Infested plants, that were grown out of treated chitosan seeds, were bigger that plants of control group, and had half as many root galls, as plants of the control group. Fertility of eelworms living on treated plants was 1,5 times lower that of control group, and they were smaller. Such results can be explained by chitosan influencing plant metabolism: treated tomato roots contain 40% less nutrition for eelworms.
 

Chitosan intensifies resistance not only of tomato roots, but also of tomato leaves: it increases enzyme activity, which enhances plant resistance towards pathogens. It appears interesting that chitosan’s protective effect is spread on tomato leaves and roots, when only seeds were treated. The researchers think that chitosan activates plant’s immune system, by binding with a specific receptor on the cell surface, which recognizes chitin and its derivatives, in other words it acts like a fake eelworm and stimulates plant to produce specific anti-worm agents well in advance.