Aspetti citochimici e metabolici del meristemi nelle varie fasi di sviluppo delle piante

Abstract

Cytological and cytochemical modifications occurring in meristematic tissues in different developmenta phases starting from ernbryogenesis are reported. These modifications involve qualitative and quantitative changes in nuclear DNA and proteins as well as in chrorn atin structure and DNA niethilation. The proliferating activity or the quiescence state of meristematic tissues follow specialized fate predictable in genetic, biochemical and metabolic terms, both in seeds and in buds. These physiological state can be reversed by substances naturally synthesied in plants promoting the mitotic cycle or leading to the cessation of cell proliferation.Meristematic cells significantly differ from each other as concerns the ability to recognize endogenous stimuli, in fact only few cells, localized among the shoot apical meristem, & e competent to accumulate the hormones invo)ved in cell differentiation and organ morphogenesis. This finding supports the hypothesis that, despite their similar shape and size, meristematic cells undergo a different State commitment before expressing any sign of differentiation.

Keywords:

• Meristematic tissues
• embryogenesis
• phase trarrisition