Abstract

RIVAS-VALENCIA, Patricia et al. Spatio-temporal analysis of Citrus tristeza virus isolates from Yucatán and Tamaulipas. Rev. Mex. Cienc. Agríc [online]. 2010, vol.1, n.4, pp.493-507. ISSN 2007-0934.

Citric (Citrus sinensis L.) commercial vegetable gardens were studied, located in the main producing regions of Yucatán from 2003 to 2006 and in Tamaulipas in 2004. In Yucatán it was carried out a space-time study of dispersion of citric tristeza, caused by Citrus tristeza virus, in presence of Toxoptera citricida Kirkaldy. The initial incidence (X₀) was of 4.41% and the final (X_f) was of 39.33%. The aggregation indexes of Morisita and Lloyd dependent of the optimum size of quadrant showed an added pattern with values between 1.41 and 2.39. Also, isolations of Citrus tristeza virus were molecularly characterized to examine the diversity of current virus. Virus isolations were analyzed with single-strand conformation polymorphism, being observed up to two haplotypes by isolation and three types of patterns in Yucatán. In Tamaulipas, with the molecular characterization, three haplotypes were identified by isolation and seven patterns. The similarity coefficient calculated for these two populations of isolations was of 0.7, being assumed a common origin for both populations. The analysis of molecular variance indicated bigger variability inside the populations (69%) and between them (31%), proving that both citric regions share variants characterized as of moderate type, which can justify the absence of symptoms attributable to tristeza. The analyses carried out to identify dispersion pattern of the isolations in field didn't evidence the dispersion between trees and rows.

Keywords : autocorrelation; coefficient of simililarity; populational structure; haplotype.

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