Portal de Periódicos da CAPES

EMBRYO SAC LACKING ANTIPODAL CELLS IN ARABIDOPSIS THALIANA (BRASSICACEAE)

1993; Wiley; Volume: 80; Issue: 7 Linguagem: Inglês

10.1002/j.1537-2197.1993.tb15298.x

1537-2197

M. Murgia, Bingquan Huang, Shirley C. Tucker, Mary E. Musgrave,

Plant Molecular Biology Research

Ultrastructure of the embryo sac lacking antipodals in prefertilization stages in Arabidopsis thaliana has been examined 2 hr before and 5 hr after manual cross pollination. The cytoplasm of both synergids before fertilization is rich in ribosomes, mitochondria, and rough endoplasmic reticulum, and also contains several microbodies and spherosomes. The filiform apparatus includes electron‐dense material and a fibrous part. Many cortical microtubules appear in the filiform apparatus area. One of the two synergids degenerates before fertilization. The synergids, the egg cell, and central cell have a rich cytoskeleton of microtubules; only the synergids appear to contain microfilaments. At the chalazal end, the antipodals are initially present but degenerate by the time of pollination in most embryo sacs in the starchless line studied. The embryo sac is completely surrounded by a wall containing an electron‐dense layer, separating it from the nucellus, including the chalazal end. When the antipodals have degenerated, the electron‐dense layer disappears at the chalazal end only, and the wall between the central cell and the nucellus is homogeneous. Between the central cell and nucellar cells no plasmodesmata are found. The membranes of both antipodal cells at the chalazal end of the embryo sac appear sinuous, like those of transfer cells. The central cell has plastids preferentially distributed around the nucleus, but the other organelles are randomly distributed. The central cell in the embryo sac and the adjacent chalazal nucellar cells show a transfer‐cell function in the embryo sac after the antipodals degenerate.