LAMP Assay to Detect <i>Elsinoë necatrix</i>, an Important <i>Eucalyptus</i> Shoot and Leaf Pathogen

Abstract

Eucalyptus scab and shoot malformation caused by <i>Elsinoë necatrix</i> is an emerging disease and a serious threat to the global commercial forestry industry. The disease was first discovered in North Sumatra, Indonesia, and now requires a simple and effective method for early pathogen detection. In this study, a rapid and sensitive loop-mediated isothermal amplification (LAMP) assay was developed for <i>E. necatrix</i>. A unique region in a secondary metabolite gene cluster was used as a target for the assay. To test robustness of the assay, LAMP was verified in 15 strains of <i>E. necatrix</i>. A specificity test against 23 closely related <i>Elsinoë</i> species and three fungal species commonly isolated on <i>Eucalyptus</i> showed that the LAMP assay exclusively identified <i>E. necatrix</i> isolates. The assay had a high level of sensitivity, able to detect 0.01 ng (approximately 400 target copies) of pure <i>E. necatrix</i> DNA. Furthermore, using a simple DNA extraction method, it was possible to use this assay to detect <i>E. necatrix</i> in infected <i>Eucalyptus</i> leaves.