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Physiological response of Arabidopsis thaliana with modified BPMs expression to moderate heat stress

In the Arabidopsis thaliana (L.) Heynh. genome, six BPM genes encode proteins containing BTB/POZ (Bric-a-Brac, Tramtrack, Broad Complex) and MATH (Meprin and TRAF Homology) domains. Recent studies have shown that BPM proteins play an important role in heat stress through the negative regulation of DREB2A, a transcription factor controlling the expression of many genes in response to drought and heat stress. Moreover, BPM1 protein was shown to be stabilized and accumulated under moderate heat stress. Physiological response of Arabidopsis seedlings with modified BPMs expression to moderate heat stress was investigated in wild type (wt), the line overexpressing BPM1 gene (oeBPM1) and the line with downregulation of BPM1, 4, 5 and 6 genes (amiR-bpm). Seedlings were exposed to 37 °C for six hours. Plant material was collected at two time points – immediately after exposure to elevated temperature and after a recovery period of 24 h at the cultivating temperature (24 °C). The status of photosynthetic apparatus was analyzed by chlorophyll a fluorescence transient (OJIP test). The content of pigments (carotenoids, chlorophyll a and b), proline, hydrogen peroxide (H2O2) and level of lipid peroxidation, as well as the activity of the antioxidant enzymes catalase, superoxide dismutase, guaiacol and ascorbate peroxidases were measured spectrophotometrically. Immediately after exposure to 37 °C, seedlings of all three lines showed reduced proline content compared to the non-stressed control groups. The photosynthetic performance index and pigment content were decreased in the wt and oeBPM1 immediately after stress. Seedlings with altered BPMs expression showed different dynamics of H2O2, lipid peroxidation and antioxidant enzymes. Different physiological response of wt, oeBPM1 and amiR-bpm to moderate heat stress could be related to altered expression of BPMs in examined lines.

Arabidopsis thaliana ; elevated temperature ; BPM proteins ; oxidative stress ; OJIP test

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