<b>First report of a ‘<i>Candidatus</i> Phytoplasma trifolii’‐related strain (16SrVI‐A) associated with</b> watermelon witches’ broom <b>disease in Iran</b>

Watermelon (Citrullus lanatus, Cucurbitaceae) is cultivated in various parts of Iran, especially the provinces Fars, Hormozgan, Kerman, Khuzistan and Hamadan. Iran world's third-largest producer watermelon globally (Food Agriculture Organization United Nations, 2016). In a 2021 survey, witches’ broom disease (WBDW) was observed field Darab area (Fars province, Iran). The main symptoms were stem proliferation, small, thickened distorted leaves, leaf yellowing, stunting, flower phyllody, virescence proliferation. No fruits produced on brooms affected plants (Fig. 1). incidence 2 ha c. 7 %. Five diseased five asymptomatic sampled analysed by PCR for presence phytoplasmas. Total DNA extracted from 0.3 g midribs using CTAB method Zhang et al. (1998). Nested performed primer pairs P1/P7 followed R16F2n/R16R2 (Lee al., 1998). Amplicons 1.25 kb obtained nested round only. amplicons cloned into Escherichia coli DH5α cells InsT/A clone™ product cloning kit (Sinnaclone, Tehran, Iran) three plasmid DNAs recombinant colonies sequenced. sequences identical, consensus sequence deposited GenBank (Accession No. OM991840). A BLASTn search showed that phytoplasma associated with WBDW had highest identity (100%) many strains belonging to ‘Candidatus Phytoplasma trifolii’ (16SrVI-A subgroup) including Bakhteghan sesame phyllody (MW272566) type strain species (AY390261). Phylogenetic analysis neighbour-joining (MEGA7) 2) clustered within 16SrVI group close ‘Ca. P. (AY390261) which representative subgroup 16SrVI-A. association 16SrVI-A disease, vectored Neoaliturus haematoceps, polyphagus leafhopper, previously reported areas Fasa, Jahrom Neyriz (Salehi 2017) adjacent Darab; may act as reservoir host infection or vice versa. Alfalfa, cucumber, tomato, marigold have also been hosts phytoplasmas Iran. Whilst there single report literature infecting India (Samuel 2014), not classified species. To our knowledge this first lanatus) worldwide, finding authors would like thank head Fars Agricultural Natural Resources Research Education Center, Shiraz, support encouragement.