Agriculture Reference
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of cold tolerance that can be achieved by independent over
expression of each one of them is very similar, along with the
fact that both over expressed genes resulted in constitutive
expression of COR15a, RD29A and KIN1, three genes involved
in the plant cold tolerance (Dubouzet et al. 2003). Rice plants
overexpressing the OsDREB1D gene have not been generated
so far, but would probably have the same tolerant phenotype of
rice plants over expression of other OsDREB1 genes. Recently
Xu et al. (2011) overexpressed a maize CBF gene (ZmCBF3)
in rice plants, and the resulting transgenics showed growth
retardation only at the seedling stage, with no yield penalty
under cold fi eld conditions. As expected transgenic plants were
cold tolerant (Xu et al. 2011).
Rice, a monocotyledonous plant that does not acclimatize
to cold, has evidence differently from Arabidopsis, which
acclimatizes to cold. To understand the stress response of rice
in comparison with that of Arabidopsis, developed transgenic
rice plants that constitutively expressed CBF3/DREB1A
and ABF3, Arabidopsis genes that function in abscisic acid-
independent and abscisic acid-dependent stress response
pathways, respectively. CBF3 in transgenic rice elevated
tolerance to drought and high salinity and produced relatively
low levels of tolerance to low temperature exposure. ABF3 in
transgenic rice increased tolerance to drought stress alone. By
using the 60Kg rice whole genome microarray and RNA gel blot
analysis identifi ed 12 and 7 target genes that were activated in
transgenic rice plants by CBF3 and ABF3, respectively, which
appear to render the corresponding plants acclimatized for
stress conditions. The target genes together with 13 and 27
additional genes are induced further upon exposure to drought
stress, consequently making the transgenic plants more tolerant
to stress conditions. Interestingly, transgenic plants exhibited
