XDH and infection: The transcription of Xp10 genes (called L and early R genes; Figure 1A) during the early stages of infection is driven by at least four Xo Eσ70 dependent promoters, whereas the transcription of Xp10 genes during the late stages of infection (called late R genes; Figure 1A) is largely driven by Xp10 RNAp (11,12).