Premium
PATTERN DETERMINATION OF THE EXINE IN CAESALPINIA JAPONICA (LEGUMINOSAE: CAESALPINIOIDEAE)
Author(s) -
Takahashi Masamichi
Publication year - 1989
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1989.tb15146.x
Subject(s) - reticulate , callose , biology , microspore , botany , ultrastructure , cell wall , stamen , pollen
Exine development in Caesalpinia japonica Sieb. et Zucc. (Leguminosae) was studied by a combination of transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM) using a freeze‐fracture method, with special attention to the initial process of exine pattern formation. The present study confirmed that the exine pattern is determined by the plasma membrane of microspores enclosed in the callose wall at the early tetrad stage. The plasma membrane, exclusive of the future apertures, invaginates and takes the form of a reticulate pattern. The reticulate pattern corresponds to the mature exine ornamentation. Protectum is the first to be laid down on the reticulate patterned plasma membrane. Probacules are initiated under the protectum and elongate basally on protruding sites of the plasma membrane. Primexine matrix is formed in coincidence with the probacules. After the protectum and probacules are completed within the callose wall, the invaginating plasma membrane becomes smooth. After the dissolution of the callose wall, endexine is organized by the accumulation of lamellated structures, and a foot layer is formed by the deposition of nonlamellated components on the developing endexine.