Identification of a divergent variant of grapevine berry inner necrosis virus in grapevines showing chlorotic mottling and ring spot symptoms

Abstract

A new variant of grapevine berry inner necrosis virus (GINV) was identified by sequencing of small RNA extracted from 'Beta' and Thompson seedless grapevines showing leaf mottle and ring spot symptoms. However, GINV was not found in symptomless samples used as a control. The complete genome sequences of two GINV isolates (KU234316-17) were determined, and these showed 75.76-89.74% sequence identity to the genome of a previously reported Japanese GINV isolate. The new variants appear to be evolutionarily distinct from the original GINV isolate. This is the first report of GINV outside of Japan.

Development of a Full-Length Infectious cDNA Clone of the Grapevine Berry Inner Necrosis Virus

“…For this purpose, we developed an infectious GINV clone to circumvent the inability to maintain plant viruses in pure cultures. We agroinoculated the infectious clone into vines, and “Beta” and “Thompson Seedless” grapevines showed obvious chlorotic mottling and ring spot symptoms, reproducing the original disease present in the field [ 15 ], thereby satisfying the third postulate. The fourth premise now considered as one of Koch’s postulates [ 35 ] states that the microorganism must be re-isolated from the newly diseased host and shown to be the same as the original inoculated microorganism.…”

“…To date, 20 species of grapevine viruses have been reported in China, including grapevine leafroll-associated virus 1–4, 7 and 13, grapevine rupestris stem pitting-associated virus, grapevine fleck virus, grapevine fanleaf virus, grapevine virus A, grapevine virus B, grapevine virus E, grapevine virus T, grapevine Pinot gris virus (GPGV), grapevine berry inner necrosis virus (GINV), grapevine fabavirus (GFabV), grapevine rupestris vein feathering virus, grapevine geminivirus A, grapevine Syrah virus-1. and grapevine red globe virus [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Although the effects of viral diseases on grapevines have been well documented [ 1 , 22 ], it is still difficult to judge the pathogenicity of a single virus to a grapevine because grapevines in the vineyard are subjected to multiple simultaneous viral infections.…”

“…Although the effects of viral diseases on grapevines have been well documented [ 1 , 22 ], it is still difficult to judge the pathogenicity of a single virus to a grapevine because grapevines in the vineyard are subjected to multiple simultaneous viral infections. Nevertheless, our previous studies, based on symptom investigations and virus identification in a large number of grapevine samples, showed that GINV, GPGV, and GFabV were associated with grapevine leaf mottling or leaf deformation in some grapevine cultivars and rootstocks in China [ 15 , 16 , 17 , 23 , 24 , 25 ].…”

“…Since it was reported in Japan, GINV has only been found in China [ 15 ]. The virus is widely present in major grapevine rootstocks and cultivars in China, and it can be associated with chlorotic mottling and ring spot in “Beta” grapevines and other cultivars [ 15 , 23 ]. However, this association did not demonstrate disease causality because these studies have not yet satisfied all Koch’s postulates.…”

“…The proteins encoded by the three open reading frames of GINV are RNA polymerase, movement protein (MP), and capsid protein (CP). Variants derived from different GINV isolates can be divided into three phylogenetic groups, and the complete genomes of three different GINV variant types have been obtained in previous studies [ 15 , 23 , 29 ]. Compared with GPGV, a close relative, GINV shows overall genetic diversity and is likely evolving under balancing selection [ 30 ].…”