SUMMARY In summer 2008, symptoms resembling those of a virus disease, i.e. chlorotic veins, deformation of the leaves and fruits, albinism and browning, were observed in chile pepper (Capsicum annuum L.) fields at Yurécuaro (Michoacán, Mexico). However, ELISA tests were negative for the viruses most commonly associated with this crop. Based on these results, and knowing that in the state of Sinaloa (México), Candidatus Liberibac- ter solanacearum (Ca.L.s.) was detected in chile plants showing shortened internodes, apical chlorosis and symptoms similar to those of “yellow psillid” in potato, it was thought that the symptoms of chile in Yurécuaro could be induced by this bacterium. In this study the etiology of the variegation of chile was determinated. Symptomatic plants were collected in the Yurécuaro re- gion in order to detect in leaves and seeds the possible causal agent by PCR and transmission electron mi- croscopy, and to transmit the pathogen by grafting, Bac- tericera cockerelli, and through seed. In leaf tissue and seed of affected plants, Ca L.s. was detected by PCR, using primers OA2 and OI2c. The bacterium was also detected in thin sectioned phloem cells of affected leaves. Disease symptoms were reproduced in plants grafted with infected tissue and in those exposed to adults of B. cockerelli collected from diseased plants. The evidence obtained indicates that the variegation of chile pepper in Yurécuaro is induced by Ca.L.s. Key words: Candidatus Liberibacter solanacearum, transmission electron microscopy, polymerase chain re- action, Bactericera cockerelli. INTRODUCTION The green chile pepper (chile, Capsicum annuum L.) is the most widely grown vegetable crop in Mexico, with a cultivated area of 149,114 ha in 2007 (SIAP, Corresponding author: R.I. Rojas-Martinez Fax: 595.95.20200 ext.1623 E-mail: rojas@colpos.mx 2007). The main producing Mexican states are: Sinaloa (694,634 tons), Chihuahua (564,256 tons), Zacatecas (209,331 tons), San Luís Potosí (133,402 tons), Tamauli- pas (125,482 tons), and Michoacán (93,424 tons). The main Michoacán municipalities growing chile are Yurécuaro, Tanhuato, Coahuayana, Vista Hermosa and Ecuandureo (SIAP, 2009). During 2008, a new phytosanitary problem of chile arose in Yurécuaro, which resembled a viral infection because of the symptoms shown by affected plants, i.e. variegation, deformation of the leaves and albinism, that recalled those induced by Tobacco etch virus (TEV) (Plant Virus Online, 2008). However, ELISA tests using commercial kits (Agdia, USA) for the presence of TEV, Tobacco mosaic virus (TMV), Tobacco ringspot virus (TRSV), Cucumber mosaic virus (CMV), Alfalfa mosaic virus (AMV), Tomato spotted wilt virus (TSWV), and Tomato aspermy virus (TAV) were negative. Knowing that Candidatus Liberibacter solanacearum (Ca.L.s.) was found in New Zealand (MAF, 2008) in chile plants with mottling, yellowing, leaf deformation and sudden death and with chile plants with symptoms similar to those of “yellow psillid” of potato in Sinaloa, (Munyaneza et al., 2009), it was hypothesized that this bacterium could be involved in the etiology of the dis- ease occurring in Yurécuaro. Ca.L.s. is also the agent of Zebra chips of potato in the USA (Abad et al., 2009) and New Zealand (Liefting et al., 2008), affects other solana- ceous crops, such as tomato (Solanum lycopersicum) (Liefting et al., 2008, 2009) and is transmitted by the psyllid Bactericera cockerelli (Hansen et al., 2008). As, mentioned, Munyaneza et al. (2009) have report- ed the presence of Ca.L.s. in symptomatic chile but did not determine whether this bacterium is the actual agent the disease. This investigation was therefore car- ried out with the aim of establishing if there were an ae- tiological relationship between Ca.L.s. and the chile var- iegation disease present in Yurécuaro. MATERIAL AND METHODS Symptomatic chile plants of cvs Centella and Tajin were collected at Yurécuaro (northwest of the Mi- Journal of Plant Pathology (2011), 93 (2), 331-335 Edizioni ETS Pisa, 2011 331 ETIOLOGY OF CHILI PEPPER VARIEGATION FROM YURÉCUARO, MEXICO M. Camacho-Tapia 1 , R.I. Rojas-Martínez 1 , E. Zavaleta-Mejía 1 , M.G. Hernández-Deheza 1 , J.A. Carrillo-Salazar 2 , A. Rebollar-Alviter 3 and D.L. Ochoa-Martínez 1 1 Instituto de Fitosanidad. Colegio de Postgraduados, Montecillo 56230, México 2 Recursos Genéticos y Productividad Genética, Colegio de Postgraduados, Montecillo 56230, México 3 Centro Regional Morelia, Universidad Autónoma de Chapingo, Morelia, Michoacán 58000, México