NGUYEN, HONG*, ROY C. BROWN, and BETTY E. LEMMON. Department of Biology, University of Louisiana @ Lafayette, Lafayette, Louisiana 70504. - Cytoskeletal patterns in endosperm development of Coronopus didymus (Brassicaceae).
Study of microtubules and F-actin during endosperm development
revealed distinct developmental domains in the micropylar chamber (MC)
containing the embryo, the large curved central chamber (CC), and the
small chalazal chamber (ChC). As is characteristic of nuclear
endosperm development, the common cytoplasm is organized into nuclear
cytoplasmic domains defined by nuclear-based radial microtubule
systems which determine placement of walls at the cellularization
stage. Both microtubules and F-actin are reorganized in preparation of
the syncytium for simultaneous cytokinesis. New findings are 1) the
interrelationships between microtubules and F-actin during development
in all three chambers, 2) an early stage of syncytial endosperm
characterized by unusual fusiform to multangular nuclei sheathed by
parallel arrays of microtubules, and 3) organization of a
multinucleate cyst of cytoplasm in the ChC that never cellularizes.
Comparison of Arabidopsis thaliana and Coronopus didymus
shows endosperm development to be a conservative process in mustard
seeds. Supported in part by NSF MCB-9726968 to R.C.B and B.E.L. and
Louisiana Board of Regents Fellowship LEQSF-1998-03-GF-28 to H.N.
Key words: Arabidopsis, embryology, F-actin, microtubules