A study conducted by scientists from Michigan State University has provided
details on how a plant protein, called CAMTA, helps plants strengthen
themselves as they anticipate long periods of cold, such as three to four
months of winter in the American midwest or northern Europe.
CAMTA proteins, which are universally found in plants, help turn on genes
that communicate freezing tolerance to plants. In the study, CAMTA proteins
were observed to also control how plants defend against harmful bacteria
under long-term cold conditions. It was found that in the cold, plants build
up high levels of salicylic acid (SA), a compound that protects them against
During long periods of cold temperature, an unknown signal is generated that
modifies CAMTA to turn on SA production. In that case, the C-terminus, or
the bottom of an amino acid chain that is stopped by a free carboxyl group,
detects the signal -- possibly a rise in cellular calcium levels -- that
enables SA biosynthesis. This observation reverses current accepted models,
which propose instead that the C-terminus blocked SA production.