THE PLANT CELL, Vol 3, Issue 6 637-644, Copyright © 1991 by American Society of Plant Biologists
Microfilament Distribution in Maize Meiotic Mutants Correlates with Microtubule Organization
C. J. Staiger and W. Z. Cande
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720
Microtubules and microfilaments often codistribute in plants; their
presumed interaction can be tested with drugs although it is not always
clear that these are without side effects. In this study, we exploited
mutants defective in meiotic cell division to investigate in a noninvasive
way the relationship between the two cytoskeletal elements. By staining
unfixed, permeabilized cells with rhodamine-phalloidin, spatial and
temporal changes in microfilament distribution during maize meiosis were
examined. In wild-type microsporocytes, a microtubule array that radiates
from the nucleus disappeared during spindle formation and returned at late
telophase. This result differed from the complex cytoplasmic microfilament
array that is present at all stages, including karyokinesis and
cytokinesis. During division, a second class of microfilaments also was
observed in the spindle and phragmoplast. To analyze this apparent
association of microtubules and microfilaments, we examined several meiotic
mutants known to have stage-specific disruptions in their microtubule
arrays. Two mutations that altered the number or form of meiotic spindles
also led to a dramatic reorganization of F-actin. In contrast,
rearrangement of nonspindle, cytoplasmic microtubules did not lead to
concomitant changes in F-actin distribution. These results suggested that
microtubules and microfilaments interact in a cell cycle-specific and
site-specific fashion during higher plant meiosis.