Agriculture Reference
In-Depth Information
overwhelming, rice breeding by means of wide crosses has been
attempted and were successful in some cases a cold tolerant
three way rice (
Oryza sativa
L.) cross involving indica, japonica
and wide compatible variety (Purohit and Majumder 2009).
Recent studies involving full genome profi ling/sequencing,
mutational and transgenic plant analysis, have provided a deep
insight of the complex transcriptional mechanism that operates
under cold stress. The alterations in expression of genes in
response to cold temperatures are followed by increases in the
levels of hundreds of metabolites, some of which are known
to have protective effects against the damaging effects of the
cold stress. Various low temperature inducible genes have been
isolated from plants. Most appear to be involved in tolerance
to cold stress and the expression of some of them is regulated
by c-repeat binding factor/dehydration responsive element
binding transcription factors. Numerous physiological and
molecular changes occur during cold acclimatization which
reveals that the cold resistance is more complex than perceived
and involves more than one pathway (Sanghera et al. 2011).
Rice seedlings are particularly sensitive to chilling in early
spring in temperate and subtropical zones and in high elevation
areas.
Improvement of chilling tolerance in rice may increase
rice production signifi cantly. MyBS3 is a single DNA binding
repeat MyB transcription factor previously shown to mediate
sugar signaling in rice. It was observed that MyBS3 also plays
a critical role in cold adaptation in rice. Gain and loss of a
function analysis indicated that MyBS3 was suffi cient and
necessary for enhancing cold tolerance in rice. Transgenic rice
constitutively over expressing MyBS3 tolerated 4ºC for at least 1
week and exhibited no yield penalty in normal fi eld conditions.
Transcription profi ling of transgenic rice over expressing or
