A search for new emerging viral (GVCV, GRBaV, GGVA, GKSV, GGDV, GMRV, GaIV, GaJV-1, GaJV-2, GaCV-1, GaCV-2 and GaCV-3) and phytoplasma diseases was conducted in 52 commercial vineyards in Bekaa and Batroun regions in Lebanon. Sampling, which consisted of collecting leaves from 252 vines showing various symptomatic (leaf mottling, red blotch, vein clearing and yellowing, leafroll and unmatured canes) and asymptomatic aspects, was conducted in late summer 2020. All collected samples were tested with RT-PCR and PCR assays, whose results showed grapevine infections solely with GGVA (9.27%) and GGDV (12.7%). Sequence analyses of PCR amplicons obtained from these two viruses showed that the Lebanese isolates of GGVA and GGDV were both 100% identical to their homologue reported in the GenBank. RT-PCR results also showed that 0.7% were infected by one pathogen and 0.35% had mixed infection.
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GGDV (12.7% of total samples) was detected in both table (9.27%) and wine (17.82%) varieties, followed by GGVA (9.5%) including 11.25% within table grapes and 6.93% within wine varieties. Candidatus Phytoplasma solani (Ca. P. solani) was found in 8 samples and their sequence analysis showed that the Lebanese isolates (LebA3, B2) share 100% of identity at the nucleotide level, and LebB1, C4, E7 and H5 share 99% with their homologue isolate reported in the GenBank, which belong to the 16SrRNA XII-A. Additionally, a new putative subgroup of the 16Sr group XII was discovered in one of the Lebanese samples, which is an intriguing finding that deserves further consideration. This preliminary study is also considered as the first report of GGVA and GGDV in Lebanon.
