Approach to the early sporangial development considering meiosis control and cellular differentiation

POZNER, R.

PLANT SYSTEMATICS AND EVOLUTION

Springer

Lugar: Viena; Año: 2001 p. 25 - 42

0378-2697

Applying current data on cell differentiation and meiosis control to the early sporangialdevelopment in angiosperms, a strict relationship between cell lineage and its differentiation fate is rejected. An evaluation of cytological features indicative of a meiotic (sporogenous) fate discards the sterilization phenomenon and introduces the premeiotic cellular differentiation (PCD) concept. The early sporangial development comprises 5 basic steps and 4 cellular stages, where PCD and meiosis extension and gradient are related to mechanisms of spore mother cell selection. Concepts here discussed explain the exceptions to the normal early sporangial development and allow a precise definition of archesporium and archespore. PCD and meiotic extension and gradient recover more information of the early sporangial development, distinguishing different developmental patterns leading to the same final result and retaining slight developmental differences. However, there are no early developmental characteristics distinctive of andro- or gynosporangia. Therefore, the heterosporic condition is not related to early developmental changes.