A primordium can be considered the simplest set of initial conditions capable of triggering growth.Within any meristem are minute primordia that resemble knobby outgrowths or ribbed inverted cones.
The plant hormone auxin has also been implicated in this process, with the new primordia being initiated at the site where the auxin concentration is the highest. Genes like STM (shoot meristem less) and CUC (cup-shaped cotyledon) are involved in defining the borders of the newly formed primordium.
Adventitious shoot formation in decapitated dicotyledonous seedlings starts with regeneration of abnormal leaves from cells not located in a shoot apical meristem
Nov 01, 2009; Abstract Regeneration of new shoots in plant tissue culture is often associated with appearance of abnormally shaped leaves. We...