First Report of Beet pseudo-yellows virus and Strawberry pallidosis associated virus in Strawberry in Peru.

Abstract

During a 2006 survey for the presence of criniviruses in Peru, large numbers of greenhouse whitefly (Trialeurodes vaporariorum) were observed infesting strawberry (Fragaria × ananassa) fields near Huaral on the central coast of Peru. Plants exhibited a wide range of symptoms including stunting and reddening of leaves. These symptoms are characteristic of those induced by the presence of the criniviruses Beet pseudo-yellows virus (BPYV) and/or Strawberry pallidosis associated virus (SPaV) together with any of a number of different strawberry-infecting viruses (1,3). The virus complex causes older leaves to develop a red color, vein and petiole reddening, roots become stunted, and plants fail to develop. Leaf samples with varying symptoms were collected from 22 plants from 2 fields, each planted with a different cultivar. Total nucleic acid was extracted, spotted onto positively charged nylon membranes, and tested by hybridization with probes specific to the minor coat protein (CPm) gene of BPYV (2) and coat protein (CP) gene of SPaV (4). Results identified the presence of BPYV, SPaV, or both viruses in mixed infections in symptomatic strawberry, while control plants were infected with each virus individually. No signal was detected in virus-free strawberry. Secondary confirmation was obtained using probes specific to the RNA-dependent RNA polymerase (RdRp) genes of SPaV and BPYV. The SPaV probe corresponded to nucleotides 6116-6599 of SPaV RNA1 (GenBank Accession No. NC_005895), whereas the BPYV probe corresponded to nucleotides 6076-6447 of BPYV RNA1 (GenBank Accession No. NC_005209). All probes were generated by reverse-transcription polymerase chain reaction (RT-PCR) amplification using sequence-specific primers, cloning of RT-PCR products into pGEM-T Easy (Promega, Madison, WI), confirmation by sequencing, and expression as digoxygenin-labeled transcript probes (Roche, Indianapolis, IN). Field 1, containing cv. Fern Sancho, had the largest number of symptomatic and infected plants (5 of 12 BPYV, 6 of 12 SPaV, and 4 of 12 with both). Only 1 of 10 plants from field 2 containing cv. Tajo Holandesa was infected, but with both SPaV and BPYV. BPYV and SPaV are transmitted by the greenhouse whitefly (T. vaporariorum), although BPYV is transmitted much more efficiently and has a broader host range than SPaV (4). Movement of these viruses in Peru is likely a result of both propagation by runners and vector transmission. To our knowledge, this is the first report of either virus in Peru.