PLANT PHYSIOLOGY , Vol 103, Issue 3 863-870, Copyright © 1993 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
Expression of Acid Invertase Gene Controls Sugar Composition in Tomato (Lycopersicon) Fruit
E. M. Klann, R. T. Chetelat and A. B. Bennett
Department of Vegetable Crops, University of California, Davis, California 95616
A wild tomato species, Lycopersicon chmielewskii, accumulates high levels
of soluble sugar in mature fruit and, unlike the domesticated tomato
species, Lycopersicon esculentum, accumulates sucrose rather than glucose
and fructose. Genetic and biochemical analyses of progeny resulting from a
cross of L. chmielewskii with L. esculentum have previously indicated that
the trait of sucrose accumulation is controlled by a single recessive gene
and is associated with low levels of acid invertase protein in the
developing fruit. Analysis of progeny from the BC2F3 generation from the L.
esculentum x L. chmielewskii cross revealed that sucrose-accumulating fruit
accumulate sugar in two phases corresponding to fruit expansion and fruit
maturation and that the majority of the sucrose was stored in the latter
phase after the fruit had reached maximum size. The only significant
enzymic difference between the sucrose-accumulating and hexose-accumulating
fruit was the lack of acid invertase activity in sucrose-accumulating
fruit. Sucrose phosphate synthase activity did not increase in the
sucrose-accumulating fruit during late development when the rate of sucrose
accumulation increased. The lack of acid invertase activity in
sucrose-accumulating fruit was correlated with inheritance of the L.
chmielewskii acid invertase gene and the absence of acid invertase mRNA in
developing fruit. This suggests that the L.chmielewskii invertase gene is
transcriptionally silent in fruit and that this is the basis for sucrose
accumulation in progeny derived from the interspecific cross of L.
esculentum and L. chmielewskii.
