Effect of the various factors on the chloroplast atpB operon genes transcription

The goal of the study was to examine the intensity of gene transcription in the plastidoperons barley leaves and its dependence upon plant age, effect of phytohormones andstate of the transcription system, and to find out how conservative the mechanism ofregulation of gene transcription within operons is.This work was performed at the first true leaves of barley of different ages and ofwhite barley mutant albostrians. The transcription intensity was determined by run-ontranscription method. To study the intensity of gene transcription, comprising the atpBoperon hybridization probes were obtained that are aligned in size (100 bp) and GC content(34-36%). For atpB operon were prepared 9 probes for: 1 - atpE gene, 2-4 - intergenicregion atpE / tRNAVal genes, 5-6 - tRNAVal intron of the gene, 7-8 - intergenicregion tRNAVal / ndhC gene and 9 - ndhC gene. Using the probes the level of 32PlabeledRNA synthesized in vitro was determined. Results showed that different parts ofthe atpB operon transcribed irregularly. The highest transcriptional activity in the intergenicspacer atpE - trnV genes had fragment DNA corresponding to probe 3, while locatednear area (probe 4) in all experiments had the lowest activity of transcription.Transcription activity increased for the intron of trnV gene (probe 5 and 6), then almostno change for the intergenic spacer trnV - ndhC genes. Similar transcription profile wasobserved for atpB operon in actively growing first leaves of 3-day-old barley seedlings,in completed growth leaves 9-day-old plants and old leaves 16- day plants. The profile ofthe intensity of genes transcription studied did not change also in the leaves treated byABA and methyl jasmonate. However, the mutant albostrians barley, which lacks thebacterial RNA polymerase type, there was a violation of differential gene transcriptionatpB operon. The results obtained allow to conclude that the rate of gene transcription inthe plastid operons of barley leaves is highly conservative. Transcription profile of genesstudied does not depend on plant age and effects of exogenous phytohormones (ABA andmethyl jasmonate). However, inactivation of the bacterial type plastid RNA polymerasecauses a significant change in the intensity of transcription of genes atpB operon.

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