Genetic Diversity of Papaya Ring Spot Virus in Puerto Rico

The Food and Agriculture Organization estimates that 20-40% of crop yield is lost due to pests and diseases. Viruses are agents that cause diseases which contribute greatly to the global yield loss. Because of this, food production is negatively affected, especially in the tropics. Carica papaya, commonly known as papaya, paw paw or lechosa, is an economically and culturally important crop in Puerto Rico. Its fruits are a source of vitamins, antioxidants and papain, an enzyme used as a meat tenderizer and other industrial uses. Despite itseconomic value, papaya production is being affected by the Papaya Ring Spot Virus (PRSV). Belonging to the Potyviridiae family, PRSV is found in tropical and subtropical regions. Its host range consists of members of the Caricaceae, Cucurbitaceae (cucurbits) and Asteraceae families. The virus has a 10kb positive single stranded RNA genome and is transmitted by aphids in a non-persistent manner. It has two biotypes, PRSV-W, which affects cucurbits but not papaya, and PRSV-P that affects both plants. When a plant is infected with the virus it can develop symptoms like leaf distortion, chlorotic mottling, shoestrings and blisters, deformed papaya fruits with ring spots, among others. If the plant is infected at early stages of its life it will not produce fruits, thus contributing to production losses. Coat protein gene sequence of PRSV from papaya and cucurbits are being analyzed to determine the variability of the viral population between biotypes in Puerto Rico. In addition, a phylogenetic analysis of PRSV isolates from around the world will indicate the relationship between the strains from the island and other countries based on sequence similarity.