Transcriptional Activity of CCA1 in Northern Population Arabidopsis thaliana Plants under Altered Light Conditions

The dynamics of the transcriptional activity of one of the key genes of the circadian network, CCA1, was analyzed under conditions of a natural light photoperiod of a long day (16L : 8D) and under an inverted light regime (8D : 16L) in A. thaliana plants of the northern natural population (Karelia). It has been shown that, under conditions of an inverted shift in the light regime, there is a sharp increase in the expression of this gene with a phase shift in the circadian rhythm by 2 h. The level of CCA1 transcriptional activity was almost two times higher compared to the natural light conditions. At the same time, the endogenous rhythm of the gene was preserved, but with a smaller amplitude. With age, 30-day-old plants grown under inverted conditions experienced a loss of endogenous CCA1 circadian rhythm. The results obtained allow us to conclude that the circadian rhythms of A. thaliana, northern natural populations, probably play an important role in adaptation to changing light conditions, and that one of the key clock genes, CCA1, plays a significant role in this process.