Sensitivity of some pepper genotypes to bacterial spot causal agent

Abstract

Bacterial spot, caused by either Xanthomonas euvesicatoria (Xe-Group A), X. vesicatoria (Xv-Group B), X. perforans (Xp-group C) and X. gardneri (Xg-Group D), formerly known as X. campestris pv. vesicatoria, is considered one of the most common pepper and tomato diseases in Serbia. So far, 11 physiological races of X. euvesicatoria bacterium were described around the world. However, four of them (P1, P3, P7, P8) have been recorded in Serbia, predominating being P8. The aim of this study was to examine the sensitivity of the 11 pepper genotypes: HS-2, Amfora, Plamena, Anita, Novosađanka, Palanačka babura, Palanačko čudo, Slonovo uvo, Brillant F1, Bihar F1 and Boni to X. euvesicatoria (RKFB 263), race P8. The experiments were carried out in a greenhouse. Pepper plants, with five fully expanded leaves, were artificially inoculated by dipping into the bacterial suspension, concentration of 106 cfu/ml and 108 cfu/ml, for 10 seconds. Early Calwonder (ECW) was used as susceptible control genotype, and its isogenic line ECW-20 withBs2 resistance gene as a resistant control. Experiments were organized as randomized block design with four replications, with five plants in each repetition. The intensity of infection was assessed by Horsfall - Barratt (HB) scale 7 and 14 days after inoculation. According to the results, pepper genotypes showed various degree of susceptibility to X. euvesicatoria (P8) differentiating into significantly different groups. Among the tested cultivars, Bihar F1 showed the highest degree of resistance to the pathogen, while all the other genotypes showed various degrees of sensitivity compared to the controls. Considering that most of the studied genotypes were sensitive to X. euvesicatoria (P8), with exception of the isogenic line ECW-20 with Bs2 resistance gene, transfer of this gene into commercial varieties of pepper would be a significant contribution to control of this economically important disease.