Influence of endogenous laserine-type phenylpropanoids in carrots on post-harvest fungal pathogens Mycocentrospora acerina and Botrytis cinerea

Laserine-type phenylpropanoids are a main group of natural bitter compounds synthesized in carrot taproots and putatively contribute to defence mechanisms against soil-borne pathogens. In this study, we analysed the relationships between the constitutive levels of two laserine compounds present in mature taproots and the extent of root infection by the two main carrot storage fungal pathogens Mycocentrospora acerina and Botrytis cinerea. Taproots of eight carrot cultivars exhibiting different levels of laserine and its isomer 2-epilaserine in the taproot periderm were inoculated with the two fungi and evaluated for diseased area with a digital image analysis system after 6 weeks incubation in a cold storage facility. The concentrations of the two phenylpropanoids showed a significant negative correlation with M. acerina and B. cinerea disease severity. We present, to our knowledge for the first time, novel insights about putative effects of laserine compounds against soil-borne fungal carrot pathogens.