Biological and molecular characteristics of some Citrus vein enation virus (CVEV) isolates from Iran

Citrus vein enation virus (CVEV), a tentative species of the genus Enamovirus, family Luteoviridae, which causes vein enation and trunk woody gall symptoms on citrus, has been recently reported from Iran. In the present research, biological and molecular properties of CVEV different isolates were studied. Following graft transmission of 29 CVEV isolates on sour orange (Citrus aurantium), volkamer lemon (C. volkameriana) and rough lemon (C. jambhiri), the results indicated that the incidence, type and severity of symptoms depend on the CVEV isolate and host (rootstock), accordingly virus isolates were classified into three groups. CVEV was transmitted by Aphis fabae with a significantly higher efficiency than that by Aphis gossypii. Thisis the first report of CVEV transmissibility by A. fabae in the world. Based on RT-qPCR results, the maximal and minimal concentrations of CVEV were determined in young bark and petioles tissues of infected sour orange seedlings, respectively. Monthly monitoring of the virus throughout the year by RT-PCR showed that CVEV was only detectable during two periods of late April to early July along with mid-September to early October, however, sensitivity of virus detection raised up to 60 percent in early December by using RT-qPCR. In the phylogenetic analysis of CVEV isolates based on nucleotide sequence of overlapped regions of ORF1 and ORF2, isolates were grouped into three clades which showed some correlation with symptomology groups.