Effect of Fungal Infection with Bipolaris sorokiniana on Photosynthetic Light Reactions in Wheat Analyzed by Fluorescence Spectroscopy

Common root rot is a widespread cereal disease caused by a plant pathogenic fungus Bipolaris sorokiniana . The influence of fungal infection on photosynthetic light reactions in soft wheat has been studied by a simultaneous registration of fast and delayed chlorophyll fluorescence induction curves as well as the redox state of a P700 pigment. In the case of infected plants, the reduction of a quantum yield of electron transport in the photosystem II (ϕ E 0 ) and performance index on absorption basis (PI ABS ), as well as the increase of energy dissipation per a reaction center (DI 0 / RC ) and ΔpH-dependent nonphotochemical fluorescence quenching ( qE ), has been observed. A reduction of the induction peak of delayed chlorophyll fluorescence at 10–50 ms has been revealed. Reactions of the photosystem I show a greater resistance to fungal infection as compared with photosystem II. Parameters of chlorophyll a fluorescence induction may be used for the early diagnostics of pathogen-induced changes in the physiological state of plants.