Infection of Tomato with R. solanacearum 
R. solanacearum strains RS1002 and RS1002-ΔpopP2 were described previously [7], [36]. R. solanacearum was streaked on tetrazolium medium (TTC) [37] and incubated at 28°C for 2 d. A single colony was grown in CPG liquid medium [38] at 28°C for 24 h. Bacterial cells were harvested and suspended with distilled water to an OD600 of 0.1 (about 1×108 cfu ml−1). Tomato cultivar Moneymaker (susceptible to R. solanacearum RS1002) plants were grown on 9 cm-diameter Jiffy peat pots containing Soil-mix and expanded vermiculite at the ratio of 1∶1 in a greenhouse at 24 to 25°C. Six-week-old seedlings at approximately the eight- to nine-leaf stage were inoculated by drenching the plant saucer near the root of each plant with 30 ml of the bacterial suspension. Plant roots were not wounded before inoculation. Observations for bacterial wilt symptoms were carried out at 5, 7, 9, 11, 13, 14 and 15 dpi according to the following scale: 0, no visible wilt; 1, one or two leaves wilted; 2, three or four leaves wilted; 3, five or six leaves wilted; 4, seven to nine leaves wilted; and 5, more than ten leaves wilted. The disease index (DI) was calculated as DI = Σ(grade × number of wilting plants)/(5× number of total plants) [39].