Expression of Six Chloroplast Genes in <i>Jatropha curcas</i> Callus under Light and Dark Conditions

Abstract

The induction of genes encoded in the open reading frames (ORFs) of chloroplast genomes have been posited to be influenced by ambient light condition. The current study focused on determining which of the six ORFs, encoding the genes ycf 1, ycf 2, psbD (photosystem II), rbcl (Rubisco), matK (Maturase K) and rpoC1 (RNA polymerase) were influenced by light. Characterization of gene expression at the whole plant level and callus stage facilitates the identification of transcripts which are differentially regulated under these environmental conditions. Specificity of these primers was tested against genomic DNA and total RNA. Transcripts of six targeted genes were detected in all three replicates of the green and white callus under light and dark conditions, except for ycf 2 gene in green callus under light. The result showed that a partial transcript of the gene ycf 2 located on the J. curcas chloroplast genome was not detectable using reverse transcription PCR. This finding was then validated using quantitative real-time PCR. The gene was suspected to be post-transcriptionally modified. The transcripts of the remaining five ORFs could be detected using quantitative real-time PCR. Specific transcripts can be identified for application as biomarkers for selection of callus for plantlet regeneration.