PLANT PHYSIOLOGY , Vol 112, Issue 3 1211-1217, Copyright © 1996 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Characterization of the Endoproteases Appearing during Wheat Grain Development
F. Dominguez and F. J. Cejudo
Instituto de Bioquimica Vegetal y Fotosintesis, Universidad de Sevilla y Consejo Superior de Investigaciones Cientificas, Facultad de Quimicas, Apartado 553, 41080-Seville, Spain
The pattern of endoproteolytic activities occurring during wheat (Triticum
aestivum, cultivar Chinese Spring) grain development was investigated.
Total endoprotease activity, assayed in solution with azocasein as a
substrate, increased during the early stages of grain development to reach
a maximum at 15 d postanthesis that was maintained until the grain was
mature. Endoprotease activity was also assayed in gradient polyacrylamide
gels co-polymerized with gelatin. The increase in endoproteolytic activity
was due to the appearance of up to 18 endoproteolytic bands that were
arbitrarily classified into five groups (A, B, C, D, and E). The presence
of serine, aspartic, metallo, and, to a lesser extent, thiol proteases in
developing wheat grains was demonstrated by the use of class-specific
protease inhibitors. The appearance of the different classes of
endoproteases during seed development was subject to temporal control;
serine proteases were more abundant at early stages and aspartic and
metallo proteases were more abundant at later stages. At intermediate
stages of development (15-20 d postanthesis), most of the endoproteases
were localized in the aleurone, testa, and embryo. The content of acidic
thiol proteases was low in the developing starchy endosperm.
