The Host Range of Subgroup 16SrII-X Phytoplasma Extends to Globe Amaranth and Other Wild Plants in Saudi Arabia

In recent years, the number of plant hosts affected by peanut witches’-broom group (16SrII) phytoplasma in Saudi Arabia has increased at a concerning speed. Since 2015 symptoms resembling phytoplasma-related diseases have been reported in Al-Qassim region affecting the wild plants globe amaranth, amaranthus, black nightshade, and buckthorn. Except for globe amaranth, which showed flower deformations, the other plants showed witches’ broom and little leaves. All the symptomatic samples collected in this study were positive for phytoplasma using universal primers targeting the 16S rRNA-encoding gene. Sequence analysis identified the phytoplasma as a member of the 16SrII-X subgroup, originally described in Saudi Arabia by our group. This is the first report of globe amaranth, amaranthus, black nightshade, and buckthorn as phytoplasma hosts in Saudi Arabia, and the first report worldwide of globe amaranth as a phytoplasma host and buckthorn being affected by 16SrII phytoplasma group.