The biological and agronomic nexus behind the resistance to protoporphyrinogen IX oxidase-inhibiting herbicides in crops

The repeated use of a single herbicide over many years results in the emergence of resistant weeds, posing a significant danger to food security. Current attempts to prevent herbicide-resistant weeds from evolving and spreading rely mostly on the creation of genetically engineered herbicide-resistant crops and the implementation of herbicide rotation strategies with varied modes of action. In recent years, protoporphyrinogen oxidase (PPO)-inhibiting herbicides have gained popularity for weed management in the field as a result of the slow evolution of PPO inhibitor resistance and the widespread emergence of weed resistance to acetolactate synthase inhibitors and glyphosate. The slow emergence of resistance to PPO herbicides enables long-term weed control and ensures the efficiency of PPO inhibitors in managing herbicide-resistant weeds. Recognizing its importance for food security, this review explores innovative strategies for developing crops resistant to PPO-inhibiting herbicides. The review in particular attempts to provide a more detailed explanation of strategies including conventional tissue culture, the prokaryotic approach, amino acid substitution, Fe-chelatase, and circadian clock-controlled gene regulation. All these contribute to our understanding of how these strategies maintain sufficient PPO enzymatic activity while moderating the inhibitory effects of the herbicide and supporting the continued growth and survival of cells under herbicide application.