Plants are subjected to an enormous number of biotic and abiotic environmental stresses during their life cycle. The responses to different stresses are very complex and include changes at the transcriptome, cellular, and physiological levels. The recognition of inductors and signaling molecules is one of the ways of inducting the plant's own defense mechanisms. The response reactions of Fragaria ananassa Duch. plants treated with chitosan of different origins and molecular weight were studied in our experiment. The plants exhibited highly reactive physiological responses. Chitosan with low molecular weight (ChI) caused intensification of phenylpropanoid synthesis, tannins formation and changed daily dynamics of secondary metabolism. Within twelve hours after treatment with ChI preparation, total phenolic and antioxidant amounts in leaves increased by 1.9 and 3.2 times respectively. Unlike ChI, the solution of high molecular weight chitosan (ChII) induced in leaves a sharp decrease of free and loosely-bound with cell walls phenolic compounds. We observed differences of plant primary response reactions to chitosan treatment. They depend on the origin of chitosan, its molecular weight and degree of deacetylation.

The article considers the effect of chitosans of different origin, molecular weight, and degree of deacetylation on the dynamics of phenolic substances in the leaves of Fragaria ananassa Duch. These substances potentially act as agents in plant responses to biotic stresses. We showed that the daily variations in individual phenolic compounds are most pronounced in the group of ellagitannins and kaempferol-3-b-D-[6-O-(E)-coumaroyl]-glucopyranoside. The most stable indicators were concentrations of kaempferol glycoside and ellagic acid pentoside. The strongest plant response to leaf treatment with low-and high-molecular-weight chitosans was a significant increase in the concentration of hexahydroxydiphenyl (HHDP)-glucose in leaves, peaking at 12 h after treatment. Treatment of F. ananassa with various forms of chitosans resulted in different concentrations of the basic phenolic substances. In particular, the plant response to a single treatment with 0.4% low-molecular-weight chitosan (LMC) was accompanied by a significant decrease in the ellagic acid concentration, after a slight increase in the first hour after treatment. The opposite effect was observed in plants after treatment with high-molecular-weight chitosan (HMC). We also determined the daily dynamics for the quantitative and qualitative composition of phenolic compounds in the control group of plants. By using the Biplot analysis, we showed a clear difference between phenol concentrations in the evening (0, 24, and 48 h) and in the morning (12 h). The strongest difference was an increase in the concentration of HHDP-glucose, galloylquinic acid, ellagic acid pentoside, kaempferol glycoside, and ellagic acid in leaves in the morning, followed by a decrease in the evening and nighttime, due to the physiological reactions of plants to external abiotic and biotic factors.

This paper present researches of callusogenesis specificity and cell differentiation of resistant (RP) and non-resistant (NRP) forms to horse-chestnut leaf miner (HCLM) of Aesculus hippocastanum according peculiarities of plant tissue primary and secondary metabolism. The most active callusogenesis was observed on DKW medium, with the addition of 0.5 mg/L kinetin and 3.0 mg/L 2,4-D. Structurally, three areas in calluses of RP and NRP forms could be recognized. The superficial part (area III) of callus in RP form was formed by cells filled with condensed tannins, with thick cell walls. A layer of parenchyma with thin cell walls underlined the outer layer of callus (area II). Numerous tracheate elements, capable of accelerated transportation of nutrients into tissues supporting cellular nutrition and differentiation, were formed among them. The internal area (area I) consisted of parenchymal cells. Many of them had in protoplasts the amorphous structures with polysaccharide and tannin complexes. The lignification of the parenchyma cell walls in callus tissues occurred under increasing of anionic peroxidases activity. This rate was five or more times higher than for the NRP form. Concerning to the RP form of Aesculus hippocastanum the viscosity of leaf cell juice may be the key factor limiting HCLM larval development. The amount of phenols in the leaves is not related with it. The kinematic viscosity of the RP form leaves (1,889 mm 2 /s) was 1.53 times higher than that of NRP form (1.214 mm 2 /s). In contrast, the content of phenolic substances was twice higher in the NRP form. The confirmed metabolic specificity of RP form can be explained by the relatively richer quantitative and qualitative composition of free amino acids in its tissues, compared to the NRP form. In general, the metabolism specificity of RP form callus tissues is a convenient model for studying the mechanisms of resistance against pathogens and pests of common horse chestnut.

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The study is dedicated to the investigation of the chitosan influence of diverse origin, molecular mass and deacetylation degree on the dynamics of both garden strawberries' phylloplane and rhizosphere aspectual composition. It was defined that Chitosans carry a varied impact on the fungal groups of both Fragaria ananassa phylloplanes' and rhizospheres', as evidenced by the dynamics of their species composition, changes in the population level and occurrence frequency. Namely, the chitosan forms under investigation had a stimulant effect on both micromycetes' and phylloplanes' dominant genus, causing an increase in strawberry leaves' population level after treatment. Nevertheless, the epiphytic fungi species structure of garden strawberry differed 48 hours after treatment with low molecular weight (LMW) and high molecular weight (HMW) chitosan solutions. It has been demonstrated that the rhizosphere mycobiota possesses different sensitivity to LMW and HMW solutions. The greatest inhibitory effect of chitosan forms was observed on penicillium, the soil CFU number of which was less compared to the control one. Thus, the Penicillium sp. amount was 47.4 thousand CFU/g of soil before treatment, becoming 4.9 and 6.3 thousand CFU/g of soil after the low molecular weight chitosan application — 12 and 48 hours after application, accordingly. On the contrary, an increase in abundance in all application variants was observed for the Fusarium genus. This can be explained by the fact that Fusarium genus fungi in the soil are predominantly in the form of mycelium hyphae, being more resistant to chitosan. As a matter of record both incubation time and the environment into which chitosan is put are no less important for its effectiveness except for physiological activity and functional properties, depending on molecular weight.