Occurrence and genetic diversity of grapevine leafroll-associated virus 4 in Algeria

Abstract

Grapevine leafroll-associated virus 4 (GLRaV-4, Ampelovirus tetravitis) has considerable genetic diversity. A survey was conducted in central, western, and southern Algeria to investigate the distribution and the genetic diversity of GLRaV-4 in commercial and autochthonous grape cultivars. DAS-ELISA detected an overall grapevine infection rate of 18.2%, and infections in a subset of samples were confirmed by RT-PCR. Analysis of the P23 protein gene sequence revealed six known phylogenetic groups, with Algerian isolates clustering in strains -4, -5, -6, -9, and -Pr of GLRaV-4. In addition to this virus, three viruses and two viroids were identified using high throughput sequencing: grapevine Pinot gris virus (GPGV, Trichovirus pinovitis), grapevine leafroll-associated virus 2 (GLRaV-2, Closterovirus vitis), grapevine fanleaf virus (GFLV, Nepovirus foliumflabelli), hop stunt viroid (HSVd, Hostuviroid impedihumuli) and grapevine yellow speckle viroid 1 (GYSVd-1, Apscaviroid alphaflavivitis). This study was the first research on genetic diversity of GLRaV-4 in Algeria.