Abstract

LOEZA-KUK, Emiliano et al. Detection of Citrus sudden death-associated virus and Haplotypes of Citrus tristeza virus in Toxoptera citricida and Aphis spiraecola and implication on citrus sudden death in Brazil. Agrociencia [online]. 2008, vol.42, n.6, pp.669-678. ISSN 2521-9766.

Individuals of Toxoptera citricida (Kirkaldy) and Aphis spiraecola (Patch) collected in 16 commercial citrus orchards of the São Paulo and Minas Gerais States of Brazil were analyzed for virus presence. Orchards of Minas Gerais were selected because citrus trees exhibit symptoms of citrus sudden death (CSD) and in São Paulo due the presence of severe strains of Citrus tristeza virus (CTV), in order to detect genomic sequences of any of these strains that could be associated to CSD. Samples made up of 20 aphids from the localities of Comendador Gomes, Frutal, Prata and Uberlândia, in the State of Minas Gerais, a CSD associated virus (CSDaV) was often found through nested RT-PCR; in samples from São Paulo, none showed positive for the same primers. With the aim to find relationships between the presence of a specific strain of CTV and the expression of CSD, specific probes were used for sequences associated to severity of isolates. The results were negative and the most promising option was to detect CTV sequence variants acquired by aphids through SSCP, to determine if there was a preference for any of the variants. No CTV sequence variants exclusive to trees with CSD symptoms were detected in aphids, but CTV was more prevalent than CSDaV in both aphid species (98 and 90% vs. 42 and 10%). Results confirm the presence of CSDaV in aphids colonizing trees with or without CSD symptoms. However, detection of CSDaV was more frequent under the CSD condition and five times higher in T. citricida.

Keywords : Aphids; virus detection; Citrus tristeza virus; Citrus sudden death-associated virus.

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