The β-galactosidase (β-Gal) expression of Pseudomonas syringae pv. syringae wild-type UMAF0158, the UMAF0158::ORF2 insertional mutant, Pseudomonas syringae pv. syringae B728a and Pseudomonas fluorescens Pf5 was detected on PMS minimal medium (without manipulation ( □ ), transformed with empty promoter-probe vector pMP220 (Grey Column) and transformed with pMPmgo, which contains the putative promoter P
(■)). The cultures were tested at 28°C and 22°C. The results are indicative of three experiments performed in triplicate. The data were analysed by an analysis of variance (ANOVA) using SPSS 8.0 software for Windows (SPSS Inc., Chicago, IL, USA). The columns labelled with an asterisk are significantly different (P < 0.01) according to the least significant difference (LSD) test.