by Philip McIntosh
JASMONATES
METHYL JASMONATE is a volatile organic compound used in plant defense
and many diverse developmental pathways such as seed germination, root
growth, and flowering. But can it help plants communicate?
THE JASMONATES , typified by jasmonic
acid (JA) and methyl jasmonate (MeJA), are plant
hormones, which, not surprisingly, have wide-
ranging effects on plant growth and development.
IN THE TRADITION of naming
compounds after their source, the first
isolate was found in the ornamental
vine commonly known as jasmine
(Jasminum sp.), although some
jasmonates are produced by fungi.
JASMONATES ARE implicated in
fruit ripening, root growth, tendril coiling
in climbing vines, and plant resistance to
insect predators and microbial pathogens.
THE MOST STUDIED
aspect of jasmonate function is
with respect to wound response,
which helps plants defend
against damage and attack.
JASMONATES
are synthesized in
various locations in
the plant and are
transported to sites of
action in the phloem,
the sap-conducting
tissue of plants.
JASMONATES EXERT their
effects in several ways, one of which is
by binding to the promoter regions of
genes to turn those genes on or off.
THE ACTION OF JA is thought
to be limited to the cells in which it is
made, but MeJA is more volatile and
more mobile within the plant.
DERIVED FROM linolenic acid,
jasmonates are fatty hormones, structurally
related to other small lipid molecules.
A HIGH PERCENTAGE of
genes activated to combat herbivory
are controlled by jasmonates.
AN INTERESTING HYPOTHESIS involving
MeJA is that it is a signal molecule allowing plants to
communicate with each other over a distance.
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