Abstract

RUIZ-GARCIA, N. et al. Reliability of direct tissue blot-ELISA and DAS-ELISA in the detection of Citrus tristeza virus and sampling in commercial orchards in Tamaulipas, Mexico. Rev. Chapingo Ser.Hortic [online]. 2009, vol.15, n.1, pp.41-47. ISSN 2007-4034.

The Citrus tristeza virus (CTV) causes a disease of regulatory interest for the Mexican citriculture. Timely and reliable sampling and diagnosis is essential for management strategies to check the spread of the brown citrus aphid, its main vector, in national territory. Because it is cheap and operationally feasible, direct tissue blot immunoassay-ELISA was compared with to DAS-ELISA, the official method for diagnosis, in order to establish an effective and efficient method for CTV detection. For the comparison, a total of 7421 trees of 11 commercial orchards of Tamaulipas, grouped by budding and infection age were tested. The direct tissue blot immunoassay technique was more sensitive and more capable of positive prognosis than DAS-ELISA in the diagnosis of CTV (P≤0.028) in trees with recent and unknown infection. Buds diagnosed positive were heterogeneously distributed throughout the canopy, described by the beta binomial function (P≤0.16-0.23). Based on this function and the reproducibility (93.2%) of the results of double petiole printing suggested an optimal sample size of 10 petioles in single print. This method was 54.9% more economical than DAS-ELISA and the diagnoses require only 17% of the time invested for DAS-ELISA. However, due to the requirements of the current Mexican official norm (NOM-031-FITO-2000), this method is recommended as a fast technique to discriminate positive trees in field sampling to be later verified with the official method of diagnosis.

Keywords : Citrus sinensis; virus; serology; diagnosis.