Agriculture Reference
In-Depth Information
under expression of MyBS3 led to the identifi cation of many
genes in the MyBS3 mediated cold signaling pathway. Several
genes activated by MyBS3 as well as inducible by cold have
previously been implicated in various abiotic stress responses
and/or tolerance in rice and other plant species. Surprisingly,
MyBS3 repressed the well known DREB1/CBF-dependent
cold signaling pathway in rice, and the repression appears
to act at the transcriptional level. DREB1 responded quickly
and transiently while MyBS3 responded slowly to cold
stress, which suggests that distinct pathways act sequentially
complementarily for adapting short and long term cold stress
in rice (Su et al. 2010). The distribution of low temperature
germinability fi tted a single gene segregation indicating that a
single dominant gene with a large effect was transferred to the
variety. This gene is tentatively symbolized as Ltg (t) (Fujino
2004).
The CBF/DREB1 genes represent one of the most signifi cant
discovery in the fi eld of low temperature adaptation and signal
transduction (Sanghera et al. 2011). Transgenic rice plants
overexpressing Os DREB1 or At DREB1 genes slowed improved
tolerance to low temperature, drought, and high salt stresses,
and elevated contents of osmo protectants such as free proline
and various soluble sugars. However, the transgenic plants
show growth retardation under normal growth conditions
(Its et al. 2006). Over expression of OsDREB1F gene also
led to transgenic rice plants with enhanced stress tolerance,
but no growth retardation effect was found, under normal
growth conditions (Wang et al. 2008). Another rice DREB1
gene (OsDREB1D) was over expressed in Arabidopsis plants,
resulting in transgenic plants in which the degree of cold
tolerance was correlated with level of OsDREB1D expression
(Zhang et al. 2009). OsDREB1D and OsDREB1A genes may
be redundant in function (Zhang et al. 2009), since the level
