Effects of viruses belonging to Potyviridae family on functional state and photosynthetic apparatus activity of beans

Abstract

The effect of viral infection on functional state and activity of the plant photosynthetic apparatus, as well as on the metabolism of photosynthetic pigments in virus infection dynamics has been investigated. A reverse transcription-polymerase chain reaction (RT-PCR) was applied for the detection of bean yellow mosaic virus and bean common mosaic virus. Total RNA was isolated using AmpliSens Ribo-Sorb DNA/RNA extraction kit. The reverse transcription reactions were carried out using the PCR test kit AmpliSens Reverta-L-100 according to the manufacturer’s protocol. Plants were mechanically inoculated by rubbing freshly extracted sap from infected plants. Fluorescence induction measurements as a mark of plant photosynthetic system activity were taken with a «Floratest» fluorometer, which makes it possible to carry out measurements in the spectral range from 670 to 800 nm. Photosynthetic pigments content was measured spectrophotometrically using an SF-46 spectrophotometer. It was shown; BCMV causes a decrease in the photosynthetic activity of beans regardless of the arrangement of leaves on the stem. In bean plants infected by BCMV, chlorophylls amount that do not participate in the photosynthetic transfer of energy to the reaction centers was increased in 1.4–2.0 times while the quantum efficiency of FS II was decreased in the 2–3 times as much as in the control. It has been established, the pigment content in infected leaves reduced significantly compared to the control plants. The chlorophyll a, b and carotenoids content decreased to 64%, 53% and 36% of the control respectively. Such pathological changes are caused by declining of active chlorophyll content (the pigment of PS II protein complexes) and its destruction. The parameters of the CFI indicate a significant inhibition of photophysical and photochemical processes during photosynthesis, as well as a Calvin cycle interruption. The chlorophyll fluorescence method can be used for rapid screening of photosynthesis, which allows making conclusion about plant status under the virus infection in a short time period.