Resistance to cold temperatures is not nearly as
critical an issue as drought or salinity for many of the world's
farmers, but it is a significant problem for agriculture. Canadian
farmers, for example, lose millions of dollars annually due to frost
damage (Functional Genomics, 2004). Methods of conferring
tolerance of cold temperatures to plants include the following:
Researchers have discovered a wheat vernalization gene, VRN2,
that represses flowering. Vernalization is the process by which
plants undergo long exposure to low temperatures before flowering.
The VRN2 gene is involved in vernalization, preventing
temperature-sensitive flowers from appearing in cold conditions and
allowing the cultivation of winter wheat varieties and other grasses in
colder climates (Nicholls, 2004).
A Canadian project called the Functional Genomics of Abiotic Stress in
Wheat and Canola Crops has been conducting ongoing research on cold
tolerance. Although no specific genes have yet been studied, the
researchers have completed "tools" such as DNA sequence databases and
protein analytical technologies that will allow identification and study
of cold-induced genes in wheat and canola. The researchers have
identified and are in the process of characterizing 433 genes expressed
in Arabidopsis, a distant relative of canola, in response to short-term
cold temperature treatment (Functional Genomics, 2004).
The Cornell scientists' addition of the trehalose gene to rice plants
conferred some degree of cold tolerance in addition to drought and
salinity tolerance (see
Drought and Salinity), making the transgenic rice plants very
promising for farmers worldwide (Garg et al., 2002).
Metals in the Soil
Drought and Salinity
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