PLANT PHYSIOLOGY , Vol 113, Issue 4 1041-1050, Copyright © 1997 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Molecular Cloning of a Ripening-Specific Lipoxygenase and Its Expression during Wild-Type and Mutant Tomato Fruit Development
K. D. Kausch and A. K. Handa
Department of Horticulture, Purdue University, 1165 Horticulture Building, West Lafayette, Indiana 47907-1165
A 94-kD protein that accumulates predominately in tomato (Lycopersicon
esculentum) fruit during ripening was purified, and antibodies specific for
the purified protein were used to isolate cDNA clones from a red-ripe fruit
cDNA library. A sequence analysis of these cDNAs and cross-reactivity of
the 94-kD-specific antibodies to the soybean lipoxygenase (LOX) L-1, L-2,
and L-3 proteins and soybean LOX L-1-specific antibodies to the 94-kD
protein identified it as a member of the LOX gene family. Maximum levels of
the 94-kD LOX mRNA and protein are present in breaker to ripe and red-ripe
stages, respectively. Expression of 94-kD LOX in different tissues from
mature green and red-ripe tomato fruits was found to be greatest in the
radial walls of ripe fruit, but immunocytolocalization using tissue
printing suggests that the highest accumulation of its protein occurs in
locular jelly. None of 94-kD LOX is expressed in nonripening mutant fruits
of any age. Never-ripe mutant fruit accumulate the 94-kD LOX mRNA to levels
similar to those obtained in wild-type fruit, but fail to accumulate the
94-kD LOX protein. Collectively, the results show that expression of 94-kD
LOX is regulated by the ripening process, and ethylene may play a role in
its protein accumulation.
