Plant Physiol, July 2001, Vol. 126, pp. 1323-1330
Role of Nitric Oxide Synthase in the Light-Induced Development of
Sporangiophores in Phycomyces blakesleeanus
Josef
Maier,
Rolf
Hecker,1
Peter
Rockel, and
Helga
Ninnemann*
Institute for Plant Biochemistry, Eberhard-Karls-University,
Corrensstrasse 41, D-72076 Tübingen, Germany (J.M., R.H., H.N.);
and Forschungszentrum Jülich, Institut für Biologie des
Stoffaustauschs, D-52425 Jülich, Germany (P.R.)
Blue light controls the development of sporangiophores in the
zygomycete Phycomyces blakesleeanus Burgeff. Light
represses the production of microsporangiophores and enhances the
development of macrosporangiophores. Inhibition of the biosynthesis of
tetrahydrobiopterin, a cofactor of NO synthase, inhibits this
photomorphogenesis. Light induces production of citrulline from
arginine in the mycelium and in sporangiophores. The citrulline-forming
activity is dependent on NADPH, independent of calcium, and inhibited
by NO synthase inhibitors. It is reduced in
tetrahydrobiopterin-depleted mycelium. Light induces emission of NO
from the developing fungus in the same order of magnitude as citrulline
formation from arginine. The NO donor sodium nitroprusside can replace
the light effect on sporangiophore development, and inhibitors of NO
synthase repress it. We suggest that a fungal NO synthase is involved
in sporangiophore development and propose its participation in light signaling.
1
Present address: Institute for Biochemistry,
University of Köln, Zülpicherstrasse 47, D-50674
Köln, Germany.
*
Corresponding author; e-mail
helga.ninnemann{at}uni-tuebingen.de; fax 49-7071-29-640019.
© 2001 American Society of Plant Physiologists
