Sequence variation in the putative effector gene <i> <scp>SIX</scp> 8 </i> facilitates molecular differentiation of <i> <scp>F</scp> usarium oxysporum </i> f. sp. <i>cubense</i>

Abstract

Fusarium oxysporum f. sp. cubense ( F oc), causal agent of fusarium wilt of banana, is among the most destructive pathogens of banana and plantain. The development of a molecular diagnostic capable of reliably distinguishing between the various races of the pathogen is of key importance to disease management. However, attempts to distinguish isolates using the standard molecular loci typically used for fungal phylogenetics have been complicated by a poor correlation between phylogeny and pathogenicity. Among the available alternative loci are several putative effector genes, known as SIX genes, which have been successfully used to differentiate the three races of F . oxysporum f. sp. lycopersici . In this study, an international collection of F oc isolates was screened for the presence of the putative effector SIX 8 . Using a PCR and sequencing approach, variation in F oc‐ SIX 8 was identified which allowed race 4 to be differentiated from race 1 and 2 isolates, and tropical and subtropical race 4 isolates to be distinguished from one another.