Karrikinolide (KAR1) is a phytoactive compound isolated from plant-derived smoke that is responsible for eliciting an array of growth responses in seeds and plant tissues. It is reported to induce rapid and vigorous growth of some seedlings such as maize and tomato at concentrations as low as one-part-per-billion. Although the use of KAR1 has shown to be of potential for enhancing plant productivity due to effects on plant growth and development, essentially nothing is known of the role of KAR1 in plant-pathogen interactions. In this study we have assessed the effect of KAR1 on tomato growth and investigated if KAR1 has the capacity to induce resistance in tomato against early blight caused by Alternaria solani.
Preliminary laboratory and subsequent glasshouse dose-response experiments showed significant effects of KAR1 on the germination and seedling growth of tomato. With these promising preliminary results, experiments are ongoing to determine whether the pretreatment of tomato plants with KAR1 provides subsequent protection when challenged with Alternaria solani.