Plastome Transcription Machinery and Peculiarities of the Expression of Its Genes during Cytokinin-Dependent Deetiolation of Arabidopsis thaliana

Abstract

Molecular mechanisms of cytokinin effect as the key activators of chloroplast biogenesis have been thoroughly investigated in recent decades; however, the role of this class of phytohormones in the regulation of expression of the plastome transcription machinery genes is obscure. In order to look into the effect of the components of the cytokinin signal system on plastid transcription machinery during deetiolation, we analyzed light- and cytokinin-dependent expression dynamics of chloroplastic RNA-polymerases, PAP proteins, and transcription factors genes upon light exposure of 4-day-old seedlings of wild type Arabidopsis thaliana (L.) Heynh. (Columbia-0) and knockout mutants for perception and transduction of the cytokinin signal. Both agents exerted a selective influence on the expression of different genes of the plastome transcription machinery. The positive effect of light and cytokinin on deetiolation probably depended on the operation of receptors AHK3 and AHK4 and response regulator genes АRR1, АRR10, and ARR12.