Cold Stress Activates the Expression of Genes of the Chloroplast Transcription Apparatus in Arabidopsis thaliana Plants
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HEMISTRY, BIOPHYSICS, AND MOLECULAR BIOLOGY
Cold Stress Activates the Expression of Genes of the Chloroplast Transcription Apparatus in Arabidopsis thaliana Plants I. A. Bychkova,*, N. V. Kudryakovaa, Corresponding Member of the RAS Vl. V. Kuznetsova, and V. V. Kusnetsova Received May 22, 2020; revised May 30, 2020; accepted May 30, 2020
Abstract—The physiological and molecular responses of Arabidopsis thaliana plants to cold stress were studied. Exposure to a low non-freezing temperature (4°C, 5 days) caused a decrease in the physiological functions and activity of a number of photosynthetic genes and elevation in expression of the cold stress gene COR15a, the product of which protects chloroplasts. It was shown for the first time that in parallel to a general inhibition of physiological functions under hypothermia, an increase in the expression of most genes for the chloroplast transcription apparatus was observed. This is obviously one of the compensatory mechanisms of adaptation aimed to maintain cellular homeostasis and physiological functions under hypothermia. Keywords: hypothermia, chloroplasts, transcription apparatus, adaptation DOI: 10.1134/S160767292005004X
Low non-freezing temperatures reduce the intensity of physiological processes and disrupt the functioning of regulatory systems in plants. Unlike many other living organisms, plants have a high adaptive potential. In the case of moderate hypothermia (2– 4°C), cold-resistant plants, one of which is Arabidopsis thaliana, are capable of tuning defense systems and increasing tolerance, which allows them to survive later at below-zero temperatures [1]. Plant adaptation to hypothermia is based on the activation of coldresponsive genes (COR), which are regulated by transfactors interacting with C-repeat binding factors (CBFs) and other transcriptional regulators induced in response to a decrease in temperature. Rapid expression of genes encoding transcription factors provides a change in the transcriptome and, as a result, a change in cellular metabolism and physiological functions. The functioning of chloroplasts under hypothermic conditions is of particular importance because retaining the photosynthetic activity during hypothermia is a necessary condition for maintaining the vital activity of the organism. The functioning of chloroplasts is ensured by the coordinated expression of plastid and nuclear genes, the nature of interaction of which under hypothermic conditions has practically not been studied. This applies primarily to the regulaa Timiryazev
Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia *e-mail: [email protected]
tion of transcription, in particular to the functioning of the plastid transcriptional apparatus. The most important stage in the regulation of expression of the plastid genome is transcription. There are two types of RNA polymerases in plastids: the bacterial-type enzyme PEP (plastid-encoded polymerase) and the phage-type monosubunit RNA polymerases NEP (nuclear-encoded polymerase) [2]. In dicots, NEP is
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