Background/Question/Methods Glucosinolates are defense-related chemicals found in cruciferous plants (e.g., cabbage, Arabidopsis thaliana), which are well-known for their toxic effects on herbivorous animals, such as insects and cattle.  Despite their toxicity, these chemicals are known to play an important role in mediating interactions between cruciferous plants and their insect pests. Upon herbivore damage, glucosinolates and myrosinase enzymes come into contact and hydrolysis products such as isothiocyanates (ITCs) are formed. In addition, other proteins such as the epithiospecifier protein (ESP) interact with myrosinases and divert the primary hydrolysis from ITCs to epithionitriles and nitriles. Using wild types and genetically-altered Arabidopsis thaliana plants, the following question was addressed: Do glucosinolate hydrolysis products in Arabidopsis thaliana influence insect performance and herbivory rates?  To answer this question, natural levels of insect herbivory were evaluated among plant genetic lines in a common garden experiment and insect fitness-related traits were measured in no-choice chamber experiments.
Results/Conclusions Results from common garden and chamber experiments revealed that ITC-producing A. thaliana lines were more effective at reducing herbivory as well as negatively impacting insect performance than those producing either nitriles or no-ITCs. This information is crucial to identify mechanisms underlying resistance to crucifer pests in A. thaliana and to apply this knowledge to integrated pest management or breeding programs of crucifer crops.