Genomic Differences Between Two Formae Speciales Causing Root Rot in Cucumber.

The host specificity of () formae speciales has been reported to be linked to effector proteins known as Secreted in Xylem (SIX). These genes are associated with the non-autonomous mobile element miniature impala (), normally distributed on the accessory chromosomes. The pattern of associated with effector genes has been used to predict candidate effector profiles which characterize formae speciales. In this study, we demonstrate the pathogenicity of strains f.sp. () ZUM2407 and f.sp. () V03-2g in a common host plant (cucumber) and compare their genomes. The ZUM2407 genome lacks genes and their homologs, in contrast to V03-2g. We predicted the total number of elements in the genome of ZUM2407 to be three-fold less than that of V03-2g (10 and 36 copies, respectively). The distribution pattern in ZUM2407 was completely different from that present in V03-2g. Candidate effector profile analysis did not predict that ZUM2407 was able to infect cucumber plants like V03-2g. Therefore, we assume that ZUM2407 has a different type of genome organization associated with pathogenicity, whose effector profile cannot be described using the -based approach.