Biology Reference
In-Depth Information
Treatment with auxin often causes parthenocarpic development in several
plant species [for review, see: [12]]. However, in some species and/or varieties,
to efficiently sustain fruit growth, the hormonal treatment of the flowers must be
repeated [13]. The finding that DefH9-iaaM mRNA is also present during later
stages of fruit development is consistent with the interpretation that in DefH9-
iaaM parthenocarpic plants, the placenta, the ovules, and the tissues derived there-
from are a source of auxin during the whole growth of the fruit. As a consequence,
they efficiently sustain fruit growth.
conclusions
The data hereby presented show the positive influence of the DefH9-iaaM par-
thenocarpic gene on eggplant productivity under both greenhouse (spring) and
open field (summer) cultivation. Taking into account the data previously ob-
tained under winter greenhouse cultivation [10], we conservatively estimate that
the overall increase in productivity is at least 30-35%. The increase in produc-
tivity of DefH9-iaaM eggplants is mainly due to a drastically improved fruit-set
under sub-optimal temperatures and to an enhanced fruit growth and weight.
Fruit quality is also improved because the fruits are seedless and do not show a
placental cavity. The qualitative improvement of DefH9-iaaM eggplant fruits is
interesting both for the fresh market and for the processing industry. During early
spring greenhouse production, DefH9-iaaM parthenocarpic hybrids always gave
fruits with an average weight suitable for fresh market commercialization, while
untransformed hybrids, under sub-optimal conditions, rarely produced commer-
cial fruits. Thus, the DefH9-iaaM gene quantitatively and qualitatively improves
eggplant production under both greenhouse and open field cultivation. In all gen-
otypes tested the DefH9-iaaM gene had a very positive effect on production and
quality parameters. Such findings are of paramount importance as the hybrids
tested have the same genetic background that the relative controls, except for the
presence of the DefH9-iaaM gene. The DefH9-iaaM gene, already known to be
expressed in the placenta and ovules during early phases of flower development, is
expressed also in mature fruits, most likely in tissues derived from the ovules.
From an economical standpoint, the main advantages conferred to eggplant
by the DefH9-iaaM gene are: i) production of marketable fruits under environ-
mental conditions adverse for fruit-set and growth; ii) reduction of cultivation
costs (energy, phytohormones and labor) necessary for off-season and open field
eggplant cultivation; and iii) enhancement of fruit quality. Last but not least,
contrary to conventional wisdom, these advantages have been achieved without
the use of either male or female sterility genes.
Search WWH ::
Custom Search