80 Bulgarian Journal of Agricultural Science, 19 (2) 2013, 80–82 Agricultural Academy IDENTIFICATION OF XANTHOMONAS STRAINS FROM TOMATO AND PEPPER AND THEIR SENSITIVITY TO ANTIBIOTICS AND COPPER Y. KIZHEVA 1 , T. VANCHEVA 1 , P. HRISTOVA 1 , M. STOYANOVA 2 , M. STOJANOVSKA 1 , P. MONCHEVA 1 * and N. BOGATZEVSKA 2 1 Sofia University “St. Kl. Ohridski”, Faculty of Biology, BG – 1164 Sofia, Bulgaria 2 Institute of Soil Science, Agrotechnologies and Plant Protection “N. Poushkarov”, BG – 1080 Sofia, Bulgaria Abstract KIZHEVA, Y., T. VANCHEVA, P. HRISTOVA, M. STOYANOVA, M. STOJANOVSKA, P. MONCHEVA and N. BO- GATZEVSKA, 2013. Identification of Xanthomonas strains from tomato and pepper and their sensitivity to antibiotics and copper. Bulg. J. Agric. Sci., Supplement 2, 19: 80–82 This study aims to characterize 136 Xanthomonas strains causing bacterial spot of tomato and pepper from different regions in Bulgaria and Macedonia. Three species were identified by PCR with species-specific primers. Xanthomonas vesicatoria affects tomato and pepper and is the dominant species in Bulgaria on tomato while Xanthomonas euvesicatoria affects only pepper. This is the first report of Xanthomonas gardneri of tomato and X. euvesicatoria of pepper in Bulgaria. Amylase activity and ability to utilize cis-aconitate of the strains vary and cannot be used for species differentiation. The tested xanthomonads were sensitive to streptomycin. Copper ions in generally used concentrations in practice were effective only against pepper strains. Key words: Xanthomonas vesicatoria, Xanthomonas euvesicatoria, Xanthomonas gardneri, bacterial spot, tomato, pepper *E-mail: montcheva@biofac.uni-sofia.bg Introduction Bacterial spot of pepper and tomato plants was first de- scribed of tomato in 1936 in Bulgaria (Kovachevski, 1936) and in 1999 in Macedonia (Mitrev and Pejcinovski, 1999) and is one of the economically most important diseases in these two countries (Mitrev and Pejcinovski, 1999; Bogatzevska et al., 2007). The taxonomy of the causal agents was subjected to many reclassifications but now the pathogens belong to four species Xanthomonas euvesicatoria, Xanthomonas vesicatoria, and Xanthomonas gardneri and Xanthomonas perforans (Jones et al., 2004). Disease control is hard and mainly based on ag- ricultural practices and copper or streptomycin-based chemi- cals. However, the occurrence of resistant strains significantly reduces their effectiveness (Obradovic et al., 2004). Clarifying the species structure in the populations causing bacterial spot in Bulgaria and Macedonia is important for effective disease control. The aim of this study is identification of the Xanthomonas species causing bacterial spot on tomato and pepper plants in Bulgaria and Macedonia according to the current classification and testing their sensitivity to antibiotics and copper as means of control. Materials and Methods Bacterial strains. 136 pathogenic Xanthomonas strains iso- lated in the period 1987-2010 were used in this study. 89 strains were isolated from tomatoes with bacterial spot (62) and as- ymptomatic weeds in tomato fields (27) in Bulgaria. 47 strains originated from diseased pepper plants from Bulgaria (30) and Macedonia (16). The type cultures (NBIMCC) X. vesicatoria 2427, X. euvesicatoria 8731, X. perforans 8729 and X. gardneri 8730 were used. Identification. Genomic DNA was extracted by a DNA iso- lation kit (STS Ltd). PCR was performed in a thermal cycler Techne TC-312 using species-specific primers for X. euvesi- catoria (Bs-XeF/Bs-XeR), X. vesicatoria (Bs-XvF/Bs-XvR),