Eustressic Dose of Cadmium in Soil Induces Defense Mechanisms and Protection Against Clavibacter michiganensis in Tomato (Solanum lycopersicum L.)

Heavy metals as cadmium are currently considered important environmental pollutants. However, based on the hormetic phenomenon, even heavy metals in low adequate dose can have a beneficial (eustressic) function in plant performance, activating defense mechanisms that allow the plant to reduce damage by pathogens. The aim of this research was to evaluate the eustressic effects of low doses of cadmium in the soil of cultivation on the induction of defense mechanisms and the possible protective effect against Clavibacter michiganensis subsp.michiganensis (Cmm) in tomato plants. The results regarding the hormetic effect of Cd onto tomato plants displayed that a dose of 60-mu g kg(-1) of soil was eustressic for significant increase in plant performance; in addition, doses of 60-mu g kg(-1) and 100-mu g kg(-1) did not show significant changes in fruit yield in comparison with control. Moreover, this eustressic dose also increased the tolerance of tomatoes against Cmm infections. This eustressic dose also significantly induced the activity of enzymes and genes associated with plant stress responses, which at least in part, explain the observed phenotype in tomatoes. These results provide evidence for Cd eustressic doses in soil for tomato cultivation that deserves to be considered in agricultural and remediation decisions when evaluating Cd effects in plants and environments.

Automated summary

This study evaluated the induction of defense mechanisms and protective effects against Cmm using low doses of cadmium in soil for tomato plants. The results showed that a dose of 60µg/kg significantly improved plant performance and increased tolerance against Cmm infections.