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Molecular cloning of a ripening-specific lipoxygenase and its expression during wild-type and mutant tomato fruit development

Kausch, K.D., Handa, A.K.
Plant physiology 1997 v.113 no.4 pp. 1041-1050
Solanum lycopersicum var. lycopersicum, ripening, protein composition, lipoxygenase, purification, enzyme activity, synthesis, ethylene, complementary DNA, messenger RNA, gene expression, cell walls, mutants, wild relatives, genetic variation, developmental stages, plant morphology, plant anatomy, genotype
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.