Expression analyses of oxidative stress katA, katG and oxyR genes in Erwinia amylovora in the viable but nonculturable state

The plant pathogen Erwinia amylovora is responsible for fire blight disease, causing serious losses in pome fruit-growing areas around the world. Difficulties in controlling fire blight have been related to the survival abilities of this pathogen in nature under different environmental conditions. One such survival strategy is the adoption of the viable but nonculturable (VBNC) state, where the cells remain viable but unable to grow on routine solid media. Because loss of culturability by VBNC cells has been related to oxidative stress, we have studied the expression of selected oxidative stress-related genes (katA, katG, and oxyR) in E. amylovora cells exposed to VBNC-inducing conditions. Gene expression was determined by reverse transcriptase polymerase chain reaction (RT-PCR), using the 16S rRNA gene as control. Initial results have shown down regulation of katA, katG and oxyR genes during the entry of E. amylovora cells into the VBNC state. However, the expression of the housekeeping 16S rRNA gene was maintained during entry and within the VBNC state.