Nuclear-Ecoded Plastid RNA Polymerases Are Components of Anterograde Control in Hormonal Regulation of Chloroplast Gene ExpressionстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 29 апреля 2021 г.
Аннотация:Phytohormones are known to play an important role in the regulation of chloroplast biogenesis.However, information on the pathways of hormonal signal perception by chloroplasts is limited. In order toanalyze the possible mechanisms of hormone action, the response to abscisic acid (ABA) and cytokinin (CKs)treatment of Arabidopsis thaliana (L.) Heynh. scabra3-2 (sca3-2) and rpotmp mutants with defective genes fornuclear-encoded plastid RNA polymerases was studied. The reaction of the rpotmp mutant usually did notdiffer from the response of wild-type plants: trans-zeatin activated the accumulation of transcripts of genesencoding the transcription apparatus and genes encoded by the plastid genome, while ABA weakly sup-pressed their expression or had no significant effect. However, the steady-state levels of gene templates of theplastid-encoded RNA polymerase (PEP-A) enzyme complex in the rpotmp mutant were higher than in wild-type plants, probably due to a compensatory mechanism that allows the mutant to enhance PEP-dependenttranscription in the absence of the RPOTmp enzyme. Dysfunction of the plastid RNA polymerase RPOTpenzyme in the sca3-2 mutant induced an altered hormonal response of the genes for plastid transcriptionalcomplex and plastid-encoded genes in comparison with the response of wild-type plants. The absence of asignificant up-regulating effect of CKs on the expression of genes encoding the transcription apparatus cor-related with the retention of the steady-state levels of transcripts for chloroplast genes and plastid proteins. Inaddition, the sca3-2 mutant had an increased steady-state expression of genes for CK metabolism: IPT3,IPT5, and CKX5. However, the response to the inhibitory effect of ABA in this mutant, on the contrary, wasmore pronounced, which is possibly caused by the changes in the steady-state levels of the transcripts of anumber of genes encoding of ABA signaling and metabolism proteins. Thus, changes in the expression ofNEP (nuclear-encoded RNA polymerases) genes under the action of hormones can be transformed into acti-vation or inhibition in the expression of chloroplast genes of nuclear or plastome coding, providing the regu-lation of chloroplast functions through the mechanisms of anterograde signaling.