First comprehensive sanitary report of citrus-infecting viruses and viroids in Uruguay

Citrus is the highest-value fruit crop in terms of international trade. However, citrus species are susceptible to several diseases caused by different pathogens which directly cause a decrease in production leading to economic losses. In the last half-century, the citrus industry in Uruguay has had a strong socio-economic impact and is also constantly evolving to stay competitive in world markets, by introduction of new varieties and improvement of production practices to obtain high yielding orchards. Nevertheless, despite the existence since 2014 of the Uruguayan National Citrus Sanitary and Certification Program, scarce information is available regarding the virus and viroid status of commercial citrus in Uruguay. The incidence of citrus tristeza virus (CTV), citrus psorosis virus (CPsV), satsuma dwarf virus (SDV), citrus exocortis viroid (CEVd), hop stunt viroid (HSVd), citrus dwarfing viroid (CDVd), citrus bark cracking viroid (CBCVd) and citrus bent leaf viroid (CBLVd) was investigated in this study, as well as CTV genotypes prevalent in the country. Molecular diagnostic assays were used to test 1175 samples including Valencia and Navel sweet oranges, Mandarin hybrids, Clementines and lemons, which were randomly collected from seven citrus-producing provinces. Only 6% of the samples were negative for the pathogens screened, while 93% of them were CTV positive. SDV, CBLVd and CBCVd were not detected. Co-infections were frequently detected, finding plants with up to four simultaneous pathogens, including CTV in all co-infected plants. This is the first comprehensive survey of several citrus-infecting viruses and viroids in Uruguay, as well as a determination of the CTV genotypes prevalent in the country