The great genetic diversity of the causal agents of bacterial spot is the main problem to the development of tomato and pepper varieties with durable resistance. Seventy two strains of Xanthomonas spp. collected from commercial fields of processing tomatoes in the states of Goiás, Minas Gerais, Pernambuco, and Bahia were classified in races according to their reactions on differential genotypes of tomato (Walter, Hawaii 7998 and NIL 216) and Capsicum [ECW (Early Calwonder), ECW-10R, ECW-20R, ECW-30R and PI 235047]. Bacterial suspensions (5 ´ 10(8) UFC/ml) were infiltrated in the abaxial leaf face of the plants at the three to five true-leaf stage. The plants were then kept in a growth chamber at 28ºC and a 12-h light/dark photoperiod. The response reactions were observed up to 36 hours after inoculation, depending on the genotype. Races T1P2, T1P8 and T3 were identified in X. axonopodis pv. vesicatoria; race T2 in X. vesicatoria; and races T2P7 e T2P8 in 'X. gardneri'. The presence of genes avrRxv and avrXv3 was confirmed by polymerase chain reaction (PCR) with specific primers in strains that produced hypersensitive reaction on 'Hawaii 7998' (races T1) and 'NIL 216' (race T3), respectively. This is the first report of races T3, T1P8, T2P7 and T2P8 in Brazil.
Lycopersicon esculentum; Xanthomonas campestris pv. vesicatoria; X. axonopodis pv. vesicatoria; X. vesicatoria; X. gardneri; genetic resistance
