P. syringae in Aesculus, Infection and Control Figure 2. The infection process of P. syringae pv. aesculi and bacterial behaviour in planta. The infection process up to 18 weeks after inoculation visualized by immunocytochemically labelling of P. syringae pv. aesculi. Arrows in A, C, K, L, M, N and P indicate the longitudinal direction. Scale bars indicate 100 mm in all micrographs except B and C where 10 mm is indicated. (A) Six days after inoculation, when the lining of lignified and suberized cells is prominent, clusters of bacteria are observed in deeper parenchyma tissues (arrowheads) by immunolabelling. Furthermore, bacteria PLoS ONE | www.plosone.org 4 July 2012 | Volume 7 | Issue 7 | e39604