Biology Reference
In-Depth Information
expressing the wheat germin
gf
-2.8
OXO
gene (Bazzalo et al. 2000; Scelonge
et al. 2000). The leaves of
OXO
transgenic sunflower constitutively expressed
the gene, showing elevated levels of OXO activity, hydrogen peroxide (H
2
O
2
),
salicylic acid, and defense gene expression. OXO releases CO
2
and H
2
O
2
from O
2
and oxalic acid (OA). H
2
O
2
appears to have roles in signal
transduction cascades that coordinate various defense responses, such as
induction of hypersensitive response and synthesis of pathogenesis-related
proteins and phytoalexins (Hu et al. 2003).
The human lysozyme gene was also found to exert resistance to
Sclerotinia sclerotioum
(Sawahel and Hagran 2006). Zygotic embryos
underwent
Agrobacterium
-mediated transformation and white mold
resistance was stably inherited. Co-transformed plants expressing the
glucanase gene from
Medicago sativa
and the chitinase gene from
Oryza
sativa
proved resistant against
Botrytis cinerea
and
S. sclerotiorum
until T
3
generation (Hess 2006).
Some
Bacillus thuringiensis
(Bt) proteins are highly toxic to pests, such as
insects, and are specific in their toxic activity, such as Cry1 (Lepidoptera-
specific), Cry2 (Lepidoptera- and Diptera-specific), Cry3 (Coleoptera-specific),
and Cry4 (Diptera-specific). The Bt
Cry1F
gene was attached to a constitutive
plant promoter and T
2
sunflower plants were subjected to enzyme-linked
immunosorbent assay (ELISA) and insect bioassay tests, showing resistance
to severe attacks of
Rachiplusia nu
larvae (Pozzi et al. 2000).
The transgenic approach has also been used to increase oil quality related
changes in the saturate/unsaturated fatty acid profiles in the sunflower fatty
acid biosynthesis pathways. A reduced stearic acid sunflower was achieved
introducing a castor (
Ricinus communis
)
-9-stearoyl-(acyl carrier protein)
desaturase (Rousselin et al. 2002).
Agrobacterium
-mediated transformation of
embryonic axes under the control of seed-specific promoters allowed stable
expression of the trait over five generations.
9.4 Overcoming of Crop Constraints through Transgenic
Sunflower and New Products
9.4.1 Low Soil Fertility
Transgenic traits that are in an experimental stage have focused on
overcoming the main constraints of cropping, and have been designed for
the control of crop adversities. Sunflower mineral nutrition research has
mainly concentrated on macronutrients in general and nitrogen in particular
soybean does not fix atmospheric nitrogen. Hence, nitrogen accumulation
may be affected under low availability conditions, as in zero-till systems in
semiarid lands (Lopez-Bellido et al. 2003).
Search WWH ::
Custom Search