Potential Threat of a New Pathotype ofPapaya leaf distortion mosaic virusInfecting Transgenic Papaya Resistant toPapaya ringspot virus

Abstract

A virus identified as a new pathotype of Papaya leaf distortion mosaic virus (PLDMV, P-TW-WF) was isolated from diseased papaya in an isolated test-field in central Taiwan, where transgenic papaya lines resistant to Papaya ringspot virus (PRSV) were evaluated. The infected plants displayed severe mosaic, distortion and shoe-stringing on leaves; stunting in apex; and water-soaking on petioles and stems. This virus, which did not react in enzyme-linked immunosorbent assay with the antiserum to the PRSV coat protein, infected only papaya, but not the other 18 plant species tested. Virions studied under electron microscope exhibited morphology and dimensions of potyvirus particles. Reverse transcription-polymerase chain reaction conducted using potyvirus-specific primers generated a 1,927-nucleotide product corresponding to the 3' region of a potyvirus, showing high sequence identity to the CP gene and 3' noncoding region of PLDMV. Search for similar isolates with the antiserum against CP of P-TW-WF revealed scattered occurrence of PLDMV in Taiwan. Phylogenetic analysis of PLDMV isolates of Taiwan and Japan indicated that the Taiwan isolates belong to a separate genetic cluster. Since all the Taiwan isolates infected only papaya, unlike the cucurbit-infecting Japanese P type isolates, the Taiwan isolates are considered a new pathotype of PLDMV. Susceptibility of all our PRSV-resistant transgenic papaya lines to PLDMV indicates that the virus is an emerging threat for the application of PRSV-resistant transgenic papaya in Taiwan and elsewhere.

Generation of hermaphrodite transgenic papaya lines with virus resistance via transformation of somatic embryos derived from adventitious roots of in vitro shoots

“…Papaya production has been seriously limited by PRSV (Purcifull et al 1984) worldwide and by Papaya leaf-distortion mosaic virus (PLDMV) in Eastern Asia (Bau et al 2008;Maoka et al 1996;Maoka and Hataya 2005). An isolate of potyvirus designated PLDMV P-TW-WF was isolated from an infected YK-CP transgenic plant in central Taiwan, and was identified as a strain of a different potyvirus PLDMV, which is serologically distinct from PRSV (Bau et al 2008).…”

“…An isolate of potyvirus designated PLDMV P-TW-WF was isolated from an infected YK-CP transgenic plant in central Taiwan, and was identified as a strain of a different potyvirus PLDMV, which is serologically distinct from PRSV (Bau et al 2008). PLDMV was first recorded in the northern part of Okinawa Island, Japan, in 1954 (Yonaha et al 1976), and spread throughout the island during 1960s (Kawano and Yonaha 1992).…”

“…The CP genes of the P-TW-WF isolate from Taiwan and the P56 isolate of Okinawa (Maoka et al 1996) share 95.1% nucleotide and 94.9% amino acid identities. Susceptibility of all PRSV-resistant transgenic papaya lines to PLDMV indicates that the virus is an emerging threat for the application of PRSV-resistant transgenic papaya in Taiwan and elsewhere (Bau et al 2008).…”

Simultaneous detection of papaya ringspot virus, papaya leaf distortion mosaic virus, and papaya mosaic virus by multiplex real-time reverse transcription PCR

“…However, papaya ringspot virus (PRSV; the family Potyviridae, the genus Potyvirus), papaya leaf distortion mosaic virus (PLDMV; the family Potyviridae, the genus Potyvirus), and papaya mosaic virus (PapMV; the family Flexiviridae, the genus Potexvirus) had been detected and threatened commercial production of papaya in China (Bau et al, 2008;Lu et al, 2008;Shen et al, 2014a;Tuo et al, 2013). Th ese three viruses produce visually indistinguishable symptoms in papaya such as mosaic, yellow-green discoloration and distortion on leaves, and water-soaking streaks on petioles (Gonsalves, 1998;Maoka et al, 1996;Sit and AbouHaidar, 1993).…”

“…Among the three papaya viruses, PRSV was considered the most widespread and destructive disease damaging papaya production in the world including China (Ye and Li, 2010;Lu et al, 2008). PLDMV was detected recently in papaya plants including PRSV-resistant transgenic papaya in Taiwan and Hainan Island (Bau et al, 2008;Tuo et al, 2013Tuo et al, , 2014, representing a new threat to papaya production in China. Moreover, although rarely found, PapMV was also detected in papaya fi elds (Cruz et al, 2009;Noa-Carrazana et al, 2006;Shen et al, 2014a).…”