Differential gene expression of chloroplast and cytosolic phosphoglycerate kinase in tobacco.

Northern blot analysis of RNA extracted from leaves of increasing age and different organs, indicates that genes encoding both isoenzymes of tobacco phosphoglycerate kinase (PGK, EC 2.7.2.3) are differentially expressed in a developmental and tissue-specific manner. The genes for both chloroplast PGK (chl-PGK) and cytosolic PGK (cyt-PGK) also show light-modulated gene expression in vivo. In dark-grown developing cotyledonary leaves of tobacco both PGK mRNAs are present, but only the concentration of the chl-PGK mRNA increased on illumination. In contrast, on transfer to darkness, the concentration of both mRNAs decreased in light-grown seedlings and then increased again on resumption of illumination.