Three-dimensional organization and dynamic changes of the actin cytoskeleton in embryo sacs ofZea mays andTorenia fournieri |
| |
Authors: | B -Q Huang Y Fu S Y Zee and P K Hepler |
| |
Institution: | (1) Department of Botany, University of Hong Kong, Pokfulam Road, Hong Kong;(2) College of Life Sciences, Wuhan University, Wuhan;(3) Department of Biology, University of Massachusetts, Amherst, Massachusetts |
| |
Abstract: | Summary Actin organization was observed inm-maleimidobenzoic acid N-hydroxysuccinimide ester(MBS)-treated maize embryo sacs by confocal laser scanning microscopy. The
results revealed that dynamic changes of actin occur not only in the degenerating synergid, but also in the egg during fertilization.
The actin filaments distribute randomly in the chalazal part of the synergid before fertilization; they later become organized
into numerous aggregates in the chalazal end after pollination. The accumulation of actin at this region is intensified after
the pollen tube discharges its contents. Concurrently, actin patches have also been found in the cytoplasm of the egg cell
and later they accumulate in the cortical region. To compare with MBS-treated maize embryo sacs, we have performed phalloidin
microinjection to label the actin cytoskeleton in living embryo sacs ofTorenia fournieri. The results have extended the previous observations on the three-dimensional organization of the actin arrays in the cells
of the female germ unit and confirm the occurrence of the actin coronas in the embryo sac during fertilization. We have found
that there is an actin cap occurring near the filiform apparatus after anthesis. In addition, phalloidin microinjection into
the Torenia embryo sac has proved the presence of intercellular actin between the cells of the female germ unit and thus confirms
the occurrence of the actin coronas in the embryo sac during fertilization. Moreover, actin dynamic changes also take place
in the egg and the central cell, accomplished with the interaction between the male and female gametes. The actin filaments
initially organize into a distinct actin network in the cortex of the central cell after anthesis; they become fragmented
in the micropylar end of the cell after pollination. Similar to maize, actin patches have also been observed in the egg cortex
after pollination. This is the first report of actin dynamics in the living embryo sac. The results suggest that the actin
cytoskeleton may play an essential role in the reception of the pollen tube, migration of the male gametes, and even gametic
fusion. |
| |
Keywords: | Actin dynamics Embryo sacs Fertilization Microinjection Torenia fournieri Lind Zea mays L |
本文献已被 SpringerLink 等数据库收录! |
|