Agriculture Reference
In-Depth Information
Table 5.3
Plants genetically modified for PAs metabolism and their tolerance response to cold
stress
Genetic modification
Plant species
Stress response
Reference
S-adenosylmethionine
decarboxylase
Lycopersicon
esculentum
Increased cold tolerance Hazarika and
Rajam
2011
adc1 and adc2 T-DNA
mutants
Arabidopsis
thaliana
Increased cold
sensitivity
Cuevas et al.
2008
S-adenosylmethionine
decarboxylase
Nicotiana taba-
cum L
Increased cold tolerance Wi et al.
2006
Spd synthase
Arabidopsis
thaliana
Increased chilling and
freezing tolerance
Kasukabe et al.
2004
applied ABA decreased the endogenous level of Put in the leaves. Authors sug-
gested that ABA is a major regulator in the response to cold stress, although it would
not play this role
via
Put.
Chickpea is sensitive to low temperatures. Under (12-15/4-6 °C) cold stress,
marked Put, Spd and Spm accumulations were observed at an early flowering stage
(Nayyar
2005
). Cold stress enhanced electrolyte leakage and declined cellular res-
piration, while exogenous 10 mM Put, applied during the flowering stage, reverted
these effects and increased floral retention, pod set and fertile pods. Also in this
crop, Nayyar and Chander (
2004
) observed that exogenous application of PAs re-
duced H
2
O
2
titer and malondialdehyde content, and raised the antioxidant levels.
These effects could be reverted by the ODC inhibitor DFMO. Oufir et al. (
2008
)
observed that Put content rose in two
Solanum tuberosum
genotypes and transiently
decreased in a
S. phureja
one, after exposure to 7C/2 °C (day/night), compared with
the control condition (21/18 °C). Upon cold, Spd and Spm contents also decreased
in
S. phureja
, while in
S. tuberosum,
Spm decreased and Spd levels did not signifi-
cantly change. In turn, the expression of SAMDC and ADC were upregulated under
cold conditions in the three genotypes.
Several plant species that have been genetically modified in their PAs metabo-
lism were studied regarding their tolerance to cold stress treatment (Table
5.3
). Ka-
sukabe et al. (
2004
) reported that the Spd synthase cDNA from
Cucurbita ficifolia
was introduced in
A. thaliana
under the control of the cauliflower mosaic virus
35S promoter
.
Transgenic plants showed a significant enhanced Spd synthase activ-
ity and Spd accumulation in leaves. Under chilling condition (5 °C), leaves of the
transgenic plants displayed a remarkable increase in ADC activity and conjugated
Spd contents, compared with the wild type. In cDNA microarray assays, it was
observed that several genes were more abundantly transcribed in chilling-stressed
transgenic
C. ficifolia
than in the corresponding wild type. One of the most remark-
able expression features in the last species was the upregulation of genes encod-
ing DREB transcription factors, and stress-protective proteins like rd29A. These
results suggested that Spd would be a regulator of stress signaling pathways that
are activated in response to chilling stress. Wi et al. (2006) introduced a SAMDC
gene from
Dianthus caryophyllus
L. into
N. tabacum
under the control of the cau-
liflower mosaic virus 35S promoter. Compared with the wild type, these transgenic
