Evolution in action: plants resistant to herbicides.
Abstract
Modern
herbicides make major contributions to global food production by easily
removing weeds and substituting for destructive soil cultivation.
However, persistent herbicide selection of huge weed numbers across vast
areas can result in the rapid evolution of herbicide resistance.
Herbicides target specific enzymes, and mutations are selected that
confer resistance-endowing amino acid substitutions, decreasing
herbicide binding. Where herbicides bind within an enzyme catalytic site
very few mutations give resistance while conserving enzyme
functionality. Where herbicides bind away from a catalytic site many
resistance-endowing mutations may evolve. Increasingly, resistance
evolves due to mechanisms limiting herbicide reaching target sites.
Especially threatening are herbicide-degrading cytochrome P450 enzymes
able to detoxify existing, new, and even herbicides yet to be
discovered. Global weed species are accumulating resistance mechanisms,
displaying multiple resistance across many herbicides and posing a great
challenge to herbicide sustainability in world agriculture. Fascinating
genetic issues associated with resistance evolution remain to be
investigated, especially the possibility of herbicide stress unleashing
epigenetic gene expression. Understanding resistance and building
sustainable solutions to herbicide resistance evolution are necessary
and worthy challenges.
- PMID:
- 20192743
- [PubMed - indexed for MEDLINE]
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