PLANT PHYSIOLOGY , Vol 111, Issue 4 1085-1096, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Complexity and Genetic Variability of Heat-Shock Protein Expression in Isolated Maize Microspores
J. L. Magnard, P. Vergne and C. Dumas
Ecole Normale Superieure de Lyon, Reconnaissance Cellulaire et Amelioration des Plantes, Unite Mixte de Recherche Centre National de la Recherche Scientifique-Institut National de la Recherche Agronomique 9938, 69364 Lyon Cedex 07, France
The expression of heat-shock proteins (HSPs) in isolated maize (Zea mays
L.) microspores has been investigated using high-resolution two-dimensional
electrophoresis coupled to immunodetection and fluorography of in vivo
synthesized proteins. To this end, homogeneous and viable populations of
microspores have been purified in sufficient amounts for molecular analysis
from plants grown in controlled conditions. Appropriate conditions for
thermal stress application have been defined. The analysis revealed that
isolated microspores from maize display a classical heat-shock response
characterized by the repression of the normal protein synthesis and the
expression of a set of HSPs. A high complexity of the response was
demonstrated, with numerous different HSPs being resolved in each known
major HSP molecular weight class. However, the extent of this heat-shock
response is limited in that some of these HSPs do not accumulate at high
levels following temperature elevation. Comparative analysis of the
heat-shock responses of microspores isolated from five genotypes
demonstrated high levels of genetic variability. Furthermore, many HSPs
were detected in microspores at control temperature, indicating a possible
involvement of these proteins in pollen development at stages close to
first pollen mitosis.