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The potential effect of karrikinolide (KAR1) in inducing resistance against Alternaria solani on tomato

Aloesi Dakuidreketi: University of Queensland

<div>Karrikinolide (KAR<sub>1</sub>) is a highly active compound belonging to the karrikin family; a novel plant growth regulator, which is generated by wildfires. It is known to stimulate an array of growth responses in a wide range of plants akin to smoke or aqueous extracts of smoke. Recently, KAR<sub>1</sub> has been reported to improve plant performance by inducing rapid and vigorous growth of some horticultural crops at concentrations as low as one-part-per-billion. Although the positive effects of KAR<sub>1</sub> has shown to be of potential in the physiological growth and development of these crops, essentially nothing is known of the role of KAR<sub>1</sub> in plant-pathogen interactions. Therefore, in this study we sought to determine if KAR<sub>1</sub> has the capacity to induce resistance in tomato inoculated with <em>Alternaria solani, </em>a necrotrophic fungus that causes early blight<em>. </em>The results of this study demonstrate for the first time that pretreatment of tomato with KAR<sub>1</sub> at 1 µgL<sup>-1</sup> reduced the development of disease caused by <em>Alternaria solani</em> and stimulated defence responses particularly in the genes of the salicylic acid pathway <em>GluA </em>and the <em>PR-1a</em> genes.</div>