Agriculture Reference
In-Depth Information
whether over-expressing or knocking down such yield related
genes can improve the grain yield potential in rice (Tripathi et
al. 2012).
Abiotic stresses are serious threats to agriculture and natural
status of the environment. Therefore, breeding for abiotic stress
tolerance in crop plants and in forest trees should be given
high research priority in plant biotechnology programmes.
Molecular control mechanisms for abiotic stress tolerance are
based on the activation and regulation of specifi c stress related
genes. These genes are involved in the whole sequence of stress
responses, such as signaling, transcriptional control, protection
of membranes, and proteins, and free radical and toxic
compound scavenging. Recently research into the molecular
mechanisms of stress responses has started to bear fruit and, in
parallel, genetic modifi cation of stress tolerance has also shown
promising results that may ultimately apply to agriculturally
and ecologically important plants. Emphasis is placed on
transgenic plants that have been engineered based on different
stress response mechanisms specially in following aspects:
regulatory controls, metabolite embryogenesis abundant and
heat shock proteins (Fig. 49).
The rice cultivars released by research in Brazil are mostly
belonging to the indica variety. They have high yield potential
and grain quality, but are extremely sensitive to cold. In the state
of Rio Grandedosul, the incidence of low temperatures during
the early stage of development is one of the major limiting
factors in rice productivity. About 100 indica genotypes were
evaluated according to the survival percentage of plants at three
leaf-stage after 10 days at 10ºC (in a growth chamber) and seven
days of recovery under normal temperature (in greenhouse
conditions). The genotypes IRGA 959-1-2-2F-4-1-4-A and IRG
A959-1-2-2F-4-1-1-D-1-CA-1 were characterized respectively as
tolerant and susceptible to low temperature stress. Rice plants
