Abstract
It has been previously demonstrated, utilizing intraspecific introgression
lines, that Lycopersicum Invertase5 (LIN5), which encodes a cell
wall invertase, controls total soluble solids content in tomato (Solanum
lycopersicum). The physiological role of this protein, however, has
not yet been directly studied, since evaluation of data obtained
from the introgression lines is complicated by the fact that they
additionally harbor many other wild species alleles. To allow a more
precise comparison, we generated transgenic tomato in which we silenced
the expression of LIN5 using the RNA interference approach. The transformants
were characterized by an altered flower and fruit morphology, displaying
increased numbers of petals and sepals per flower, an increased rate
of fruit abortion, and a reduction in fruit size. Evaluation of the
mature fruit revealed that the transformants were characterized by
a reduction of seed number per plant. Furthermore, detailed physiological
analysis revealed that the transformants displayed aberrant pollen
morphology and a reduction in the rate of pollen tube elongation.
Metabolite profiling of ovaries and green and red fruit revealed
that metabolic changes in the transformants were largely confined
to sugar metabolism, whereas transcript and hormone profiling revealed
broad changes both in the hormones themselves and in transcripts
encoding their biosynthetic enzymes and response elements. These
results are discussed in the context of current understanding of
the role of sugar during the development of tomato fruit, with particular
focus given to its impact on hormone levels and organ morphology.
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