The virus causing passionfruit woodiness disease in Taiwan is reclassified as East Asian passiflora virus

Abstract

Based on filamentous particles, aphid transmission, and symptoms of distorted, size-reduced, woody fruits, the major potyvirus associated with passionfruit woodiness disease (PWD) in Taiwan has been regarded as Passionfruit woodiness virus (PWV) for decades. In this study, the genomes of four potyvirus isolates, originally collected from orchards with PWD in Taiwan and re-designated as Poty-TW, Poty-0920-6, Poty-dpd and Poty-pt, were sequenced for molecular characterization. Our results revealed that the CP genes of Poty-TW and Poty-0920-6 share nucleotide (nt) identities/amino acid (aa) identities of 97.7/95.9 and 98.5/97.2%, respectively, with that of East Asian passiflora virus (EAPV) isolate AO of Japan, and the CP genes of Poty-dpd and Poty-pt share nt/aa identities of 95.3/96.2 and 94.9/97.6% respectively, with that of EAPV isolate IB of Japan. The genomic sequences of PWD-associate viruses in Taiwan also share high degrees of homology with that of EAPV-AO (TW and 0920-6 isolates > 98%) and EAPV-IB (dpd and pt isolates > 88%). However, the CP genes of four PWD-associated viruses from Taiwan share only 67.6-69.4% nt identities with that of PWV Australia MU isolate, does not satisfy the ICTV criteria (> 76%) to be regarded as a strain of PWV. A field survey with 175 samples from different areas of Taiwan demonstrated that the PWD-associated potyvirus is mainly caused by EAPV. Hence, our results indicate that the major potyvirus causing PWD in Taiwan should be reclassified as EAPV.