|Swisher Grimm, Kylie|
|VELASQUEZ-VALLE, RODOLFO - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)|
|MENA-COVARRUBIAS, JAIME - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)|
|Munyaneza, Joseph - Joe|
Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2016
Publication Date: 7/19/2016
Citation: Swisher, K.D., Velasquez-Valle, R., Mena-Covarrubias, J., Munyaneza, J.E. 2016. Occurrence and molecular detection of Spiroplasma citri in carrots and Circulifer tenellus in Mexico. Journal of Plant Pathology. 98:355-360.
Interpretive Summary: Plant pathogens are a serious threat to carrot production in the United States and across the world. Researchers at USDA-ARS Wapato in Washington, in collaboration with scientists at INIFAP in Mexico, assessed whether pathogens were associated with diseased carrot plants recently observed in commercial carrot fields in Zacatecas, Mexico. It was determined that the diseased carrots were infected with Spiroplasma citri, an insect-transmitted pathogen of economic importance in carrots and other crops. Information from this research will help carrot producers reduce damage caused by this plant pathogen by effectively monitoring and controlling leafhoppers, the insect vector of this pathogen.
Technical Abstract: In the fall of 2014, carrot plants in Zacatecas, Mexico, were found with yellow, brown (chlorotic), and/or purple-colored leaves, small and/or rolled leaves, and hairy, deformed, and/or small roots. Molecular diagnostics of these symptomatic plants failed to detect phytoplasmas in these samples, but identified Spiroplasma citri in 58 and 94% of the samples using polymerase chain reaction targeting the Spiralin and arp1 genes, respectively. Sequence analysis confirmed the presence of S. citri in the symptomatic carrot samples, and also identified a novel, putative adhesion-related protein (arp) gene in one carrot sample. S. citri is a phytopathogenic mollicute that is transmitted by various leafhopper species. Beet leafhoppers (Circulifer tenellus Baker) collected in the same state of Zacatecas, Mexico, were subsequently tested for S. citri infection, of which 35% were positive using polymerase chain reaction targeting the arp1 gene. Sequencing analysis confirmed the presence of S. citri in the leafhoppers. Results of this study constitute the first report of S. citri in carrot and C. tenellus in Mexico. Previously in the Americas, S. citri in carrot, designated carrot purple leaf disease, has only been reported in Washington and California in the United States. The presence of S. citri in carrots and its insect vector in Mexico, suggests that this pathogen could become a large threat to many vegetable industries in this region of Mexico, including the carrot industry.