Histochemical and Cytophotometric Estimation of DNA, RNA and Proteins in the Shoot Apex of Nicotiana tabacum Linn

Abstract

Changes in structure and zonation occur in the shoot apical meristem of Nico-tiana tabacum Linn. during development from the mature embryo to the repro-ductive phase. The amounts of DNA, RNA and total proteins were quantified and related to the above changes. The plumular apex showed an almost uniform dis-tribution of DNA, RNA and total proteins. DNA and RNA increased during the vegetative and reproductive growth whereas proteins decreased during the vegetative period followed by increase in the reproductive stage. In the vegetative apex the distribution pattern of DNA, RNA and total proteins followed the cytohistological zonation with the peripheral zone (PZ) showing higher content per unit area. In the floret apex the axial located cells showed less DNA, RNA and total proteins till carpel initiation. The entire apex seems to be involved in the reorganisation during transition to flowering.