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Engineered Resistance Against Papaya ringspot virus in Venezuelan Transgenic Papayas

May 2004 , Volume 88 , Number  5
Pages  516 - 522

Gustavo Fermin , Valentina Inglessis , Cesar Garboza , Sairo Rangel , and Manuel Dagert , Department of Biology, Universidad de Los Andes, Mérida, Venezuela ; and Dennis Gonsalves , USDA - Pacific West Area, Pacific Basin Agricultural Research Center, Hilo, HI 96720

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Accepted for publication 24 December 2003.

Local varieties of papaya grown in the Andean foothills of Mérida, Venezuela, were transformed independently with the coat protein (CP) gene from two different geographical Papaya ringspot virus (PRSV) isolates, designated VE and LA, via Agrobacterium tumefaciens. The CP genes of both PRSV isolates show 92 and 96% nucleotide and amino acid sequence similarity, respectively. Four PRSV-resistant R0 plants were intercrossed or selfed, and the progenies were tested for resistance against the homologous isolates VE and LA, and the heterologous isolates HA (Hawaii) and TH (Thailand) in greenhouse conditions. Resistance was affected by sequence similarity between the transgenes and the challenge viruses: resistance values were higher for plants challenged with the homologous isolates (92 to 100% similarity) than with the Hawaiian (94% similarity) and, lastly, Thailand isolates (88 to 89% similarity). Our results show that PRSV CP gene effectively protects local varieties of papaya against homologous and heterologous isolates of PRSV.

Additional keywords: Carica papaya, post-transcriptional gene silencing, transgenic virus resistance

The American Phytopathological Society, 2004