The Crosstalk between Cytokinin and Auxin Signaling Pathways in the Control of Natural Senescence of Arabidopsis thalian
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The Crosstalk between Cytokinin and Auxin Signaling Pathways in the Control of Natural Senescence of Arabidopsis thaliana Leaves M. N. Danilovaa, *, A. S. Doroshenkoa, N. V. Kudryakovaa, A. V. Klepikovab, c, V. Yu. Shtratnikovad, and V. V. Kusnetsova a
Timiryazev Institute of Plant Physiology, Moscow, 127276 Russia Institute of Science and Technology, Moscow, 143026 Russia c Institute for Information Transmission Problems, Moscow, 127051 Russia d Belozersky Research Institute of Physical and Chemical Biology, Moscow, 119234 Russia *e-mail: [email protected] bSkolkovo
Received April 10, 2020; revised April 10, 2020; accepted April 10, 2020
Abstract—Natural senescence of leaves is a regular physiological process subjected to a certain genetic program and controlled by various phytohormones. Cytokinins (CKs) play a crucial role in the leaf-senescence control being negative regulators of this process. We previously reported on the prolonged vegetative growth and the development of a double knockout ahk2ahk3 mutant of Arabidopsis thaliana Heynh. (L.) for the genes encoding CK receptors. According to the data of the transcriptomic analysis and real-time RT-PCR of selected genes performed in this study, the delay of leaf senescence in ahk2ahk3 mutants is accompanied by enhanced (4–281-fold) expression of the group of SAUR (small auxin-up RNA) genes encoding auxin response proteins and by upregulation of the SSPP (senescence-suppressed protein phosphatase) gene, whose expression level significantly (137-fold) exceeded that in a wild-type transcriptome. Thus, it is quite possible that under significant inhibition of the CK signaling leaf senescence in Arabidopsis plants regulated via a compensatory mechanism connected with changes in the expression of the SAUR gene family and a certain pool of genes related to the auxin transport and signaling. Keywords: Arabidopsis thaliana, senescence, mutants, transcriptome, trans-factors, cytokinins DOI: 10.1134/S1021443720060035
INTRODUCTION Senescence is a kind of age-specific programmed cell death occurring at the cellular, tissue, organ, and organism levels that results in withering of a plant [1]. In spite of its destructive character, senescence is a dynamic physiological process, which is strictly regulated at the genetic level [2]. Leaf senescence represents a special form of this process accompanied with the mobilization and recycling of nutrients into developing seeds or other parts of a plant [2]. Phytohormones play an important role in leaf-senescence control; they can either inhibit the process (cytokinins and partially auxins) or positively regulate it (salicylic, abscisic, and jasmonic acids and ethylene). The existence of mechanisms of crosstalk between cytokinins (CK) and auxins is beyond question. Multiple links between the systems of synthesis, perception, and transport of these two plant hormones provide a wide range of possibilities for their mutual Abbreviations: CK—cytokinins; real-time RT-PCR—real-time reverse transcription polymerase chain
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