A. Introduction of constitutive fluorescent reporter genes separately into the P. syringae pv. phaseolicola 1302A chromosome and PPHGI-1 genomic island to create B. P. syringae pv. phaseolicola F341 containing eYFP introduced into the chromosome upstream of glmS using a Tn7 delivery system and eCFP within the non-coding region of PPHGI-1 and C. P. syringae pv. phaseolicola F532 with dsRFP in the chromosome and eGFP in PPHGI-1. D. Schematic depiction of PPHGI-1 excision (with loss of GFP expression) from P. syringae pv. phaseolicola F532 within the plant environment with E. fluorescence detectable in channels R, dsRFP; G, eGFP and O, with overlapping channels. Loss of eGFP fuorescence would also report the deletion of PPHGI-1 from bacteria. Abbreviations are as follows: FP-1, fluorescent protein either eYFP or dsRFP; FP-2, fluorescent protein either eGFP or eCFP; TT, transcriptional terminators; NCR, non-coding region in PPHGI-1; ‘*’ denotes constitutive reporter expression. SpeI - AsiSI region is a secondary rare-cloning site. The position on PPHGI-1 of genes used in this study are avrPphB 17,471–18,274 bp and xerC 105,384–106,805 bp [6]. The genes for the fluorescent proteins have been inserted in non-coding region at position 55,660–56, 299 bp.