PLANT PHYSIOLOGY , Vol 110, Issue 2 483-491, Copyright © 1996 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
A Wound- and Methyl Jasmonate-Inducible Transcript Coding for a Myrosinase-Associated Protein with Similarities to an Early Nodulin
J. Taipalensuu, A. Falk and L. Rask
Uppsala Genetic Center, Department of Cell Research, Swedish University of Agricultural Sciences, Box 7055, S-750 07, Uppsala, Sweden
Myrosinase is regarded as a defense-related enzyme in the Brassicaceae and
is capable of hydrolyzing glucosinolates into various compounds, some of
which are toxic. Several myrosinase isoenzymes exist, and some of them have
been found in association with nonmyrosinase proteins. One of these
associated proteins, myrosinase-associated protein (MyAP), was purified
from seeds of Brassica napus both in complexes with myrosinase and in a
free form. MyAP is a glycosylated, 40-kD protein with at least one
intramolecular disulfide bridge. A monoclonal anti-MyAP antibody
precipitated myrosinase activity from B. napus seed extracts and in these
complexes both a 65- and a 70-kD myrosinase were present. The subsequent
cloning and analysis revealed the existence of a gene family encoding MyAP
or MyAP-related protein and that transcripts corresponding to MyAP in
nonwounded plants are found predominantly in seeds. At least some members
of the gene family exhibited responsiveness toward wounding and methyl
jasmonate vapor. MyAP displayed considerable similarity to an early nodulin
(ENOD8) from Medicago sativa and to a proline-rich protein (APG), described
as anther specific, from Arabidopsis thaliana and B. napus. Similarity to
expressed sequence tags from both A. thaliana and Oryza sativa has also
been found.
