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process (e.g. protected cultivation). However, during winter cultivation of egg-
plant varieties in unheated greenhouses in the Mediterranean area, the negative ef-
fect of suboptimal environmental conditions on fruit production is usually coun-
teracted by treating flower buds with plant growth regulators. Phytohormonal
treatments make the production process more expensive due to the cost of both
chemicals and labor.
In principle, the genetic engineering of plants allows one to confer a trait of
interest to different species and within a species to all the varieties of interest. To
confer parthenocarpic fruit development, a chimeric gene has been constructed
[6]. Specifically, the DefH9-iaaM gene contains the coding region of the iaaM
gene from Pseudomonas syringae pv. savastanoi under the control of the placenta
and ovule-specific promoter from the DefH9 gene from Anthirrinum majus[6].
The iaaM gene codes for a tryptophan monoxygenase, which produces indolac-
etamide that in turn, is either chemically or enzymatically converted to the auxin
indole-3-acetic acid. To date, the DefH9-iaaM chimeric gene has been shown
to cause parthenocarpic fruit development in tobacco [6], eggplant [6], tomato
[7,8], strawberry and raspberry [9].
We have previously shown that DefH9-iaaM eggplants outperform control
plants during protected winter cultivation by an average of 33% [10]. The pres-
ent manuscript presents data on the agronomic performance of DefH9-iaaM
eggplant hybrids during spring and summer cultivation. Seed-derived F1 plants
perfectly reflects the real agronomical situation of eggplant production. In addi-
tion, they have allowed to demonstrate that the transgene is active after meiosis
and give satisfactory results in the hemizygous state. Different types of eggplant
hybrids have been evaluated during springtime in unheated greenhouses in two
different locations. To evaluate GM parthenocarpic eggplants under optimal en-
vironmental conditions, a single trial has been carried out using two different
genotypes under standard open field cultivation during summertime. Further-
more, we demonstrate that the DefH9-iaaM gene is expressed during late stages
of fruit development.
results and discussion
Greenhouse spring Production
Spring production was evaluated in trials performed in two different locations:
Monsampolo and Pontecagnano. Spring production was divided into early pro-
duction, consisting of the first four harvests, and total production, consisting of
sixteen harvests. Early spring production corresponds to the cultivation period
from March to the first half of May, with temperatures somewhat low for fruit-set
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