PLANT PHYSIOLOGY , Vol 111, Issue 4 1313-1319, Copyright © 1996 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Differential Expression of Two Endo-1,4-[beta]-Glucanase Genes in Pericarp and Locules of Wild-Type and Mutant Tomato Fruit
C. Gonzalez-Bosch, D. A. Brummell and A. B. Bennett
Mann Laboratory, Department of Vegetable Crops, University of California, Davis, California 95616
The mRNA accumulation of two endo-1,4-[beta]-D-glucanase genes, Cel1 and
Cel2, was examined in the pericarp and locules throughout the development
of normal tomato (Lycopersicon esculentum) fruit and the ripening-impaired
mutants rin and Nr. Both Cel1 and Cel2 were expressed transiently at the
earliest stages of fruit development during a period corresponding to cell
division and early cell expansion. In the pericarp, the mRNA abundance of
both genes increased markedly at the breaker stage; the level of Cel1 mRNA
decreased later in ripening, and that of Cel2 increased progressively. Cel2
mRNA levels also increased at the breaker stage in locules but after
initial locule liquefaction was already complete. In rin fruit mRNA
abundance of Cel1 was reduced and Cel2 was virtually absent, whereas in Nr
Cel1 was expressed at wild-type levels and Cel2 was reduced. In wild-type
fruit ethylene treatment slightly promoted the mRNA accumulation of both
genes. In rin fruit ethylene treatment strongly increased the mRNA
abundance of Cel1 to an extent greater than in wild-type fruit, but Cel2
mRNA was absent even after ethylene treatment. These two
endo-1,4-[beta]-D-glucanase genes, therefore, do not show coordinated
expression during fruit development and are subject to distinct regulatory
control. These results suggest that the product of the Cel2 gene
contributes to ripening-associated cell-wall changes.
