Reversible, cell-heritable changes during the development of tobacco pith tissues

Area of Science:

• Plant biology
• Molecular biology
• Epigenetics

Background:

• Cytokinin habituation is a process where plant cells lose their requirement for exogenous cytokinin.
• Nicotiana tabacum pith parenchyma exhibits inducible and noninducible cell populations with distinct cytokinin requirements.
• These phenotypes are considered determined states inherited by cells during plant development.

Purpose of the Study:

• To investigate if noninducible tobacco cells can acquire inducibility for cytokinin habituation.
• To explore the potential epigenetic basis of changes in cytokinin habituation competence.
• To characterize the developmental potential of habituated cells derived from different cell types.

Main Methods:

• Regeneration of plants from cloned lines of noninducible tobacco cells.
• Assessment of cytokinin habituation phenotypes in regenerated plant tissues.
• Comparative analysis of habituated cell lines derived from inducible and noninducible precursors.

Main Results:

• Pith tissue from plants regenerated from noninducible cell lines displayed the inducible phenotype, indicating a switch in competence.
• The change in habituation competence was found to be reversible, rapid, and dependent on cellular developmental state, suggesting an epigenetic mechanism.
• Two distinct forms of the habituated state were identified based on developmental potential, differing in cytokinin requirements of regenerated tissues.

Conclusions:

• Noninducible plant cells can regain inducibility for cytokinin habituation, challenging the notion of fixed determined states.
• Epigenetic factors, influenced by developmental context, play a crucial role in regulating cytokinin habituation competence.
• The developmental potential of habituated cells is linked to their origin, impacting the characteristics of regenerated plants.