First Report of Citrus Bent Leaf Viroid and Citrus Dwarfing Viroid in Argentina

Abstract

Citrus Bent Leaf Viroid (CBLVd) and Citrus Dwarfing Viroid (CDVd), from genus Apscaviroid, are two of the widely distributed citrus viroids among the eight reported to date. They have been found to induce reduction in canopy volume and fruit production in citrus trees on trifoliate and trifoliate orange hybrids rootstocks. Moreover, citrus trees infected only with CBLVd or in combinations with Citrus Exocortis Viroid (CEVd), Hop Stunt Viroid (HSVd) and CDVd have been associated with a poor development of the root system. Samples of citrus trees showing viroid symptoms collected from citrus orchards in Tucumán, Salta, and Jujuy provinces (NW region in Argentina) were initially indexed on citron (Citrus medica) and then analyzed by s-PAGE. These samples were found to be infected with different viroid species, among them, CEVd and HSVd have been already identified. In order to determine the presence of other viroids, we performed a RT-PCR assay using specific primers for CBLVd, CDVd, CBCVd and CVd-V. Forty two samples including 15 lemons, 15 oranges, 8 grapefruits, 2 citrumelos and 2 Cleopatra mandarins were analyzed so far. On the basis of amplification of the appropriately sized DNA, CDVd was detected in thirty eight samples and CBLVd in all grapefruit samples. CBCVd and CVd-V were not found in any samples to date. Analysis of the sequence of amplicons revealed 96% and 97% identity with CBLVd GenBank reference sequences, and 96% to 98% with CDVd GenBank reference sequences. This is the first report of CBLVd and CDVd in citrus trees in Argentina.