The effect of the pathogenic fungus Bipolaris sorokiniana (Sacc.) Shoem. on chlorophyll degradation in the seedlings of spring barley (Hordeum vulgare L.)

The study of the mechanisms of plant defense reactions during pathogenesis is closely related to the elucidation of the role of chloroplasts as intracellular sensors that sensitively respond to external stimuli. An important criterion for assessing the severity of development of the pathological process in plants is the amount of chlorophyll, which is determined by the balance between the processes of biosynthesis and breakdown of pigment molecule in the plant cell. The objects of the study were the seedlings of spring barley (Hordeum vulgare L.) chaffy variety Raider of Belarusian selection. Seedlings of different ages (3-, 7-, and 10-day-old) were infected with spores of the fungus Bipolaris sorokiniana (Sacc.) Shoem., the causative agent of helminthosporiosis. Forty-eight hours after inoculation, an analysis of the initial stages of chlorophyll degradation was carried out based on the activity of the main hydrolytic enzyme, chlorophyllase, and the content of chlorophyllide and pheophytin in the primary barley leaves. Ontogenetic differences in the degradation process of phytol-containing chlorophyll pigments, as well as an increase in chlorophyllase activity and the degree of pheophytinization of pigments under the influence of the pathogenic fungus B. sorokiniana were discovered. Pigment indicators such as the content of phytolic and non-phytolic forms of chlorophyll and the content of pheophytin can be used as criteria for the early diagnosis of barley plant damage by a fungal pathogen and for assessing the degree of degree of infection.

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