Molecular identification of diverse ‘Candidatus Phytoplasma’ species associated with grapevine decline in Iran

Abstract

Grapevine (Vitis vinifera) is one of the most important fruits in Iran where the provinces of Qazvin, Lorestan and Markazi are main producers. During 2013–2015, vineyards located in these provinces were surveyed to verify the presence of phytoplasma. The sample collection was based on symptomatology including decline, leaf yellowing and shortening of internodes. Total DNA was extracted from symptomatic and symptomless grapevine samples and used in nested‐polymerase chain reaction (PCR) assays with phytoplasma ribosomal primers (P1/Tint followed by R16F2n/R2, R16mF1/mR1, R16(I)F1/R1 or 6R758f/16R1232r). Nested‐PCR products were obtained only for symptomatic samples while samples from symptomless plants yielded no PCR products. Restriction fragment length polymorphism (RFLP) analyses with Tru1I, TaqI and Tsp509I and direct sequencing of amplicons followed by phylogenetic analyses indicated the presence of ‘Candidatus Phytoplasma fraxini’, ‘Ca. P. aurantifolia’, ‘Ca. P. solani’ and ‘Ca. P. phoenicium’‐related strains. In Marzaki province, there ‘Ca. P. aurantifolia’ strains were mainly detected, while in the other two provinces, all the four ‘Candidatus species’ were identified with the prevalence of ‘Ca. P. solani’‐related strains. In both provinces in one case, mixed phytoplasma infection was also detected by RFLP analyses. The presence of different phytoplasmas in positive samples indicates great phytosanitary significance due to grapevine economic importance for country. Grapevine phytoplasma infection represents a threat for other crops suggesting grapevine as alternative host species for the phytoplasmas already reported in Iran, while the ‘Ca. P. fraxini’ is for the first time identified in Iran.

History and Current Status of Phytoplasma Diseases in the Middle East

“…The symptoms of GY include reddening and yellowing in red and white cultivars, necrosis of terminal buds, the appearance of black pustules in infected shoots, downward curling of leaves, and the decline and drying of the berries [ 97 ]. Seven phytoplasma groups have been reported associated with GY symptomatic grapevine plants, including the 16SrII-B subgroup in Iran [ 98 ], 16SrVI in Syria [ 99 ], 16SrI, 16SrIII, and 16SrXII in Israel [ 61 ], and 16SrI-B, and 16SrIX in Turkey [ 100 ].…”

“…P. fraxini’), and 16SrIX-C (‘ Ca . P. phoenicium’), have been detected in symptomatic grapevines in the center and south of Iran [ 98 , 104 , 105 ].…”

Molecular study of phytoplasmas associated with pistachio yellows in Iran

“…On the basis of sequence homology and phylogenetic of R16F2n/R2 amplicons, the detected phytoplasmas in pistachio plants from Qom and Markazi provinces (PAr11, PAr2, PB25, PB33, PB39 and PB62) are molecularly classified as members of the 16SrIX (pigeon pea witches’ broom group), the same group that contains almond witches broom phytoplasma (Salehi & Izadpanah, ), grape decline (Ghayeb Zamharir, Paltrinieri, Hajivand, Taheri, & Bertaccini, ; Salehi, Salehi, Taghavi, & Izadpanah,) and peach yellows (Ghayeb Zamharir, ), which are three economically important diseases in Iran. Although, phytoplasmas associated with these diseases are members of 16SrIX, they are not source of pistachio little leaf and yellows phytoplasma.…”

“…(Kordestan province, Iran). The phytoplasmas detected in pistachio plants from Yazd Province (PM1 and P25) are molecularly classified as members of the 16SrXII group, the same group containing grape decline phytoplasma (Ghayeb Zamharir et al., ) in Iran. The pistachio phytoplasma strains from Yazd Province had more than 99% homology with a phytoplasma associated with Candidatus Phytoplasma solani strain EC‐FA‐Mamasani Eucalyptus little leaf (Accession No. )…”

First report of a ‘Candidatus Phytoplasma phoenicium‘‐related strain (16Sr IX) associated with Salix witches' broom in Iran

“…Other hosts of ‘ Ca. P. phoenicium’ include almond in Lebanon, and numerous hosts including almond, grapevine, peach, pistachio, Bidens alba and Chrysanthemum morifolium in Iran (Ghayeb Zamharir et al , 2017). To our knowledge this is the first report of a ‘ Ca.…”