The Rural Voice, 1989-09, Page 19Top: Canola seedlings being exposed to flea beetles.
Bottom: The apparatus used to collect gas from stinkweed and canola plants for
analysis. Stinkweed, a relative of canola, offers clues to flea -beetle resistance.
Seedlings are put in the three bell jars on the back of the bench and the gas emitted by
them is collected in the bottles on the heaters.
the production of attractant chemicals
could be removed from the plant so
insects could not find it. Or genes for
repellant substances could be identi-
fied and inserted into the plants'
genetic makeup.
The scientists at the Winnipeg
station are looking at several options.
Lamb hopes that a chemical to deter
feeding can be isolated from stink-
weed and transferred to canola.
Stinkweed is related to canola (they
are both in the family Brassicae), so
it contains many of the same chemi-
cals. But even though stinkweed has
the same chemical attractants to flea
beetles as canola, the beetles won't
eat it.
"If we are really
truthful about cleaning
up the environment, we
need more of this sort of
work," says biochemist
Robert Bodnaryk.
Something is stopping the beetles
from feeding on the stinkweed leaves.
And work done in Alberta has shown
that when liquid from crushed stink-
weed leaves is painted onto canola
plants, flea beetles won't feed on
them. Lamb hopes the genes that code
for the chemical in stinkweed can be
transferred to canola using genetic
engineering technology. Without
genetic engineering, this sort of trans-
fer would be impossible because the
two plants are not related closely
enough to be interbred.
The first step in this process is
the isolation of the feeding deterrent.
This is being done by Bodnaryk, who
is collecting the gases produced by
growing stinkweed plants and analyz-
ing them. Once the compound has
been identified, a search can be made
for the genes that govern its
production.
This technique is also used to iden-
tify the attractant chemicals produced
by canola plants. Bodnaryk says that
another scientist at the station, Dr.
Palaniswamy Pachagounder, is trying
to reduce or change the smell of
canola plants so the beetles like them
less. And if there were no odour at all,
beetles would not be able to find the
plants in the first place.
In addition, Lamb has identified
some physical traits that give plants
resistance to beetle feeding. Several
years ago he found that the hairy seed
pods of the mustard Gisilba are unat-
tractive to beetles.*** Beetles given
pods with the hairs picked off one side
ate the bare side but left the hairy side,
indicating that the resistance was not
chemical -based. Hairy pods, if bred
into canola varieties, could protect the
crop against flea beetles, Lamb says.
This resistance was uncovered by
"screening," which can be described
SEPTEMBER 1989 17