Transcriptomic Differences Between Two Fusarium oxysporum Formae Speciales During Cucumber Infection.

Fusarium oxysporum f. sp. radicis-cucumerinum (Forc) V03-2g and Fusarium oxysporum f. sp. radicis-lycopersici (Forl) ZUM2407 both cause foot and root rot in cucumber, but differ in host range. Forc V03-2g possesses Secreted in Xylem (SIX) effector genes, whereas Forl ZUM2407 does not, raising questions about their distinct infection strategies on this host. Using comparative transcriptomic analysis (in cucumber at 7 and 14 days post-inoculation (dpi) and in tomato at 2 dpi) we show that Forl ZUM2407 induces a delayed defense response in cucumber compared to Forc V03-2g. In turn, Forc V03-2g rapidly activates accessory chromosome effectors on cucumber, while Forl ZUM2407 initially deploys core chromosome genes, activating distinct from Forc V03-2g accessory genes only by 14 dpi. Thereby, Forc V03-2g and Forl ZUM2407 use distinct accessory gene repertoires (unique to each strain) and distinct core gene transcription strategies to infect the same host.