Light regulates motility, attachment and virulence in the plant pathogen P seudomonas syringae pv tomato DC 3000

Summary P seudomonas syringae pv tomato DC 3000 ( P to) is the causal agent of the bacterial speck of tomato, which leads to significant economic losses in this crop. P to inhabits the tomato phyllosphere, where the pathogen is highly exposed to light, among other environmental factors. Light represents a stressful condition and acts as a source of information associated with different plant defence levels. Here, we analysed the presence of both blue and red light photoreceptors in a group of P seudomonas . In addition, we studied the effect of white, blue and red light on P to features related to epiphytic fitness. While white and blue light inhibit motility, bacterial attachment to plant leaves is promoted. Moreover, these phenotypes are altered in a blue‐light receptor mutant. These light‐controlled changes during the epiphytic stage cause a reduction in virulence, highlighting the relevance of motility during the entry process to the plant apoplast. This study demonstrated the key role of light perception in the P to phenotype switching and its effect on virulence.