Changes in protein synthesis without evidence of DNA methylation in barley chloroplasts during leaf growth and development

Resumen

The polypeptides synthesized by isolated chloroplasts and the endonuclease restriction patterns of plastid DNA have been investigated during greening, expansion, maturity and senescence of the primary leaf of barley. Greening chloroplasts synthesized diverse polypeptides, among which those presumably corresponding to large subunit of rubisco (54 kDa) and photosystem II D1 protein (32 kDa). During leaf expansion and maturation the activity of protein synthesis decreased and the electrophoretic profile of the polypeptides synthesized changed. The pattern of the restriction fragments produced by digestion with EcoRI, HaeIII, HpaII and MspI was indistinguishable among plastid DNAs of leaves at different stages of development. Moreover, there was no difference between the restriction patterns produced by the isoschizomers HpaII and MspI which differ in their sensitivity to methylation. Apparently, no plastid DNA rearrangement, gain, loss or methylation causes the decrease in mRNAs and protein synthesis and the change in polypeptides synthesized by chloroplasts during leaf growth and senescence. © 1992.