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an engineered super fungus to control weeds
The article below shows an interesting but very dangerous strategy for
weed control without chemicals. The history of genetics is well endowed
with examples of super pathogens that recombine and mutate to extend
host range. There must be liability associated with the potential
destruction caused by such inventions. Even the solution of introducing
genetic remedies into the crops effected by super fungi provides cold
comfort to organic farmers or unprepared neighboring farms.
Nature Biotechnology
October 2002 Volume 20 Number 10 pp 1035 - 1039
Engineering hyper virulence in a mycoherbicidal fungus for efficient
weed control
Ziva Amsellem1, Barry A. Cohen1, & Jonathan Gressel
Agents proposed for biocontrol of major weeds in arable row-crop
agriculture have not met expectations because an evolutionary balance
has developed between microorganism and weed, even when the
mycoherbicide is used inundatively at very high levels (>104
spores/cm2). Sufficient virulence can be achieved by transferring genes
to the microorganism, tipping the evolutionary balance. Virulence was
increased ninefold and was more rapidly effected; furthermore, the
requirement for a long duration at high humidity was decreased by
introducing NEP1 encoding a phytotoxic protein, to an Abutilon
theophrasti–specific, weakly mycoherbicidal strain of Colletotrichum
coccodes. The parent strain was at best infective on juvenile cotyledons
of this intransigent weed. The transgenic strain was lethal through the
three-leaf stage, a sufficient time window to control this
asynchronously germinating weed. Strategies of coupling virulence genes
with fail-safe mechanisms to prevent spread (due to broadened host
range) and to mitigate transgene introgression into crop pathogens could
be very useful in the biocontrol of major weeds in row crops.
.