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EFFECT OF STRESS CONDITIONS ON PHOTOSYNTHETIC EFFICIENCY OF Arabidopsis thaliana SEEDLINGS WITH MODIFIED BPM1 GENE EXPRESSION

Six genes encoding BPM proteins are present in the Arabidopsis thaliana genome. Previous studies have shown that the BPM1 protein plays an important role in the regulation of various developmental processes, as well as in the phenotypic and physiological adaptability of plants to adverse environmental conditions [1, 2]. Depending on the severity and duration, different stress conditions can have negative effects on plant metabolism. One of the most likely effects is reduced photosynthesis, resulting in decreased plant growth, development, and productivity. Today, there are several methods for determining photosynthetic efficiency. One of the most commonly used is the measurement of chlorophyll a (Chl a) fluorescence by the OJIP test. The method is based on recording of polyphasic Chl a fluorescence induction curve during high-intensity illumination of dark-adapted leaves [3]. The aim of this work was to study the effect of heat, salinity, and osmotic stress on the photosynthetic efficiency of Arabidopsis seedlings using the OJIP test. To question the possible role of BPM1 protein in plant response to stress conditions, two lines were used – the wild type (wt) and the line with overexpressed BPM1 gene (oeBPM1). Chlorophyll a fluorescence was measured 12th day after the beginning of germination. The effect of heat stress was studied on 12-day-old seedlings exposed to a temperature of 43 °C for one hour. For salinity and osmotic stress, seedlings were cultured from day 5 to day 12 on medium containing 75 mM NaCl and 150 mM mannitol, respectively. Regardless of the stress condition applied, seedlings of both lines showed a decrease in performance index (PIABS) compared to non-stressed plants. From several measured parameters (ϕPO, F0, VJ, M0), the amount of active reaction centers of photosystem II was calculated. The results obtained indicate a decrease in their amount due to stress conditions, which could explain the decrease in PIABS. Measurement of Chl a fluorescence by the OJIP test revealed no difference between the wt and oeBPM1 lines in response to the stress conditions studied.

Arabidopsis thaliana ; heat stress ; BPM proteins, OJIP test

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