The Rural Voice, 1989-09, Page 20as the classical method of creating
a resistant variety. For years, Dr.
Lamb has simply exposed different
varieties of canola to natural flea
beetle populations, picking out those
that aren't eaten. It doesn't matter
how the resistance is caused, just as
long as it is there. Dr. Lamb says the
process has yielded "lines that do
substantially better against flea beet-
les. They aren't good enough but we
have made quite a lot of progress."
Bodnaryk is exploring yet another
option. He is trying to make canola
biochemically incompatible with the
insects by changing the sterol makeup
of the plants. Sterols are very much
like the cholesterols that cause health
problems for humans. They are used
by insects as the basis for ecdysone,
a hormone necessary for moulting
and growth. As insects cannot manu-
facture cholesterols, they must get
them in their diet. Insects eating the
modified plants will not get enough
nutrition and will die.
This option, unlike the work with
stinkweed, is based on an established
premise. "We have known for 40
years that insects must get sterols from
their diet," Bodnaryk says. Certain
fungicides, for example, convert plant
sterols into types that insects can't use.
As Bodnaryk says, "There is no
question that the process works. We
have fed bertha armyworms [another
pest of canola] with plants that have
an altered sterol profile, and they don't
do very well, eventually dying."
Fungicides applied to canola have
similar effects on flea beetles.
Bodnaryk hopes that it may be
possible to create a canola plant with
a permanently altered sterol profile.
"The trick is to change the plants
enough so that the insect doesn't like
it but the plant will grow."
Plants with the altered sterol
profile appear to grow less well,
Bodnaryk adds. But he says that a
canola plant that suffers fewer side
effects from the fungicide has recently
been identified.
Bodnaryk comments that all
this work aimed at making a resistant
plant is only preliminary. "At this
point in the work we are ignorant of
any agronomic concerns such changes
may bring," he says. "For example, a
plant that tastes horrible to flea beetles
may transfer the same taste to the
seeds." At this point, the task is sim-
ply to identify any and all processes
that may lead to a resistant plant.
Lamb concurs with this assess-
ment. He says his objective now is
to identify genotypes that have resis-
tance. These plants will then be given
to breeders who will try to incorporate
the resistance feature into canola.
Lamb is working with canola breeders
at the University of Manitoba and the
Agriculture Canada Saskatoon
Research Station.
The work is held up, however,
by an irritating characteristic of flea
beetles. Although remarkably fertile
in the wild (their huge numbers attest
to this), flea beetles shut down their
reproductive processes upon entering
the lab. As a result, lab cultures of the
insect are rare, and mass rearing is
impossible. This means that much of
the screening work, which can be done
in the lab, must wait until beetles can
be collected in the field.
This is a frustrating situation.
Bodnaryk says that "right now we are
able to do one set of selections [of
plants demonstrating resistance] per
year. We would like to do 1,000 per
year by moving the selection process
into the lab."
The volume of screenings is
also limited by manpower, which
is becoming scarcer at government
research stations. Bodnaryk wonders
if the sterol work, which needs a
number of people working on it, will
continue.
"If we are really truthful about
cleaning up the environment," he says,
Dr. Robert Bodnaryk
"we need more of this sort of work."
Doubly frustrating is that the work is
not complicated, just time-consuming.
No special skills or equipment are
needed to run most of the screening
experiments.
But Bodnaryk also says that the
transfer using genetic engineering
technology is guaranteed: a resistant
plant will eventually be available to
farmers. This technological benefit,
says Bodnaryk, "will stay in Canada
and benefit Canadian farmers."
This should give Canadians
something to think about. In a country
with more than a million unemployed
people, the development of a plant that
could save agriculture up to $100
million a year as well as clean up the
environment may be delayed 5 or 10
years for the want of workers.0
* Canadian Entomologist, Vol. 114:
827-840. ** Canadian Journal of Plant
Science 68: 85-93. *** Canadian Journal
of Plant Science 60: 1439-1440.
Xew Mustard
Resists Drought
by /an Wylie-Toal
Canola may soon be facing another
threat to its existence, this time from a
weed that has been transformed into a
crop.
Plant breeders at Agriculture
Canada's Saskatoon Research Station
have come up with a hardy oilseed
mustard that matches canola in terms
of oil and meal quality.
Dr. Gerhard Rakow, a plant breed-
er in Saskatoon, says the mustard is a
different species in the same genus
(Brassica) as canola. Mustard has
many important features that make it
desirable as a crop, he says, including
a high tolerance to drought conditions.
But the positive characteristics of
mustard have long been overshadowed
by the high glucosinolate content of
the seeds. This chemical makes the
18 THE RURAL VOICE