The psbE-F-L-J operon from chloroplast genome of Populus deltoides: Cloning, nucleotide sequence and transcript analysis

Abstract

A 5-5-kbp HindIII fragment carrying psbE-F-L-J operon from the chloroplast DNA of Populus deltoides was cloned and nucleotide sequence was determined for a 1672-bp region. The coding regions showed more than 90% homology at nucleotide sequence level with plastid-encoded psbE, psbF, psbL and psbJ genes of higher plants. Pairwise alignments of psbE, psbF, psbL and psbJ coding regions of poplar with published sequences from other plants were carried out to analyse the nature of nucleotide substitutions. The 5' and 3' untranslated regions of the genes revealed high variability among different organisms both in terms of homology and the number of nucleotides. Northern hybridization data indicated that all four genes of psbE-F-L-J operon were transcribed as a single tetracistronic message which was not subjected to further processing into smaller transcripts. The transcript showed quantitative increase in mature leaves.