Detecting Fusarium oxysporum f. sp. elaeidis by using loop-mediated isothermal amplification

We developed a Loop-Mediated Isothermal Amplification (LAMP) to detect Fusarium oxysporum f. sp. elaeidis (FOE) causal agent of fusarium wilt in oil palm. The assay was designed based on partial sequences of effector protein Secreted In Xylem (SIX8, SIX10 and SIX13) and P450 cytochrome-oxidase. The isolates used were classified as FOE, presumed-FOE and non-FOE/other Fusarium spp. based on previously published pathogenicity assay studies. The LAMP assay detected FOE DNA isolated from root tissues of oil palm seedlings. The SIX8 primers detected all FOE isolates, including other presumed-FOE and non-FOE isolates. The SIX10 and SIX13 could not detect FOE and presumed-FOE isolates. The P450 cytochrome-oxidase primer detected all isolates of FOE, presumed-FOE and non-FOE. Without isolating FOE DNA from soil, the LAMP assay could not detect FOE directly in inoculated soil. Detection time for all primers was below 30 min. Annealing derivative curves were used for assessing the level of specificity for both SIX8 and P450 cytochrome-oxidase, but none of the LAMP primers could distinguish between FOE, presumed-FOE and non-FOE isolates. This assay could be suitable for FOE detection of oil palm in nurseries and serve as an important biosecurity tool to screen oil palm germplasm exchanged between oil palm growing countries.