Molecular Typing of ‘Candidatus Phytoplasma solani’ in Iranian Vineyards

Abstract

Grapevine (Vitis vinifera L.) is one of the most important horticultural crops in Iran, with >200,000 ha of cultivated area. Recently, outbreaks of the grapevine yellows Bois noir that is associated with phytoplasma strains related to ‘Candidatus Phytoplasma solani’ were recorded in several Iranian regions. This has resulted in severe economic losses. We carried out a survey in 2015, followed by collection of leaf samples from symptomatic grapevines and weeds. Because no information is available on the molecular epidemiology of ‘Ca. P. solani’ in Iran, multiple gene analyses were carried out here according to molecular characterization of the tuf and vmp1 genes. From the molecular characterization, all of the samples (i.e., grapevines, weeds) were infected with tuf b type. Detailed molecular characterization of the vmp1 gene (i.e., PCR–restriction fragment length polymorphism, sequence analysis) defined five molecular types: V1, V4, V10, V15, and V20. The abundance of Convolvulus arvensis in vineyards and detection of the same ‘Ca. P. solani’ molecular types in grapevines and weeds suggest that C. arvensis has a major role in Bois noir epidemiology of Iranian vineyards. Therefore, control strategies should be developed to manage these host plants to reduce inoculum sources of the phytoplasma in vineyards.

Symptomatology, (Co)occurrence and Differential Diagnostic PCR Identification of ‘Ca. Phytoplasma solani’ and ‘Ca. Phytoplasma convolvuli’ in Field Bindweed

“…P. solani' infection in field bindweeds is far from elucidated. Plants can be either symptomatic or non-symptomatic while infected at similar rates and frequencies e.g., [3,6,10,12,14,18,[21][22][23][24]. In our study, only at locality Kladovo symptomatic bindweed plants were infected solely with 'Ca.…”

“…According to numerous studies, specific symptoms described as "stunting, dwarfism, proliferation, leaf yellowing and/or color alteration" are displayed in the naturally 'Ca. P. solani'-infected C. arvensis plants acting as reservoirs and inoculum source for the vector [3,[10][11][12][13][14][15][16][17][18]. Conversely, several more recent studies indicate that non-symptomatic plants of C. arvensis are a natural source of 'Ca.…”

Sequence Analysis of New Tuf Molecular Types of ‘Candidatus Phytoplasma Solani’ in Iranian Vineyards

“…A total of 124 grapevine samples were collected during surveys carried out from mid-September to the beginning of October in 2016 and 2017 in local vineyards which constituted of white and red varieties. This intensified the phytosanitary monitoring for grapevine yellows carried out in 2015 in vineyards located in the Azarbaijan Gharbi, Azarbaijan Sharghi, Zanjan, Qazvin, Fars, Lorestan and Khorasan Razavi provinces of Iran, as previously reported by Jamshidi et al [ 9 ]. Total nucleic acids were extracted from 1 g fresh petioles of symptomatic grapevines from old and young leaves using the cetyltrimethylammonium bromide method, as described by Daire et al [ 32 ].…”

“…In Iranian vineyards, molecular typing of ‘ Ca . P. solani’ strains associated with BN led to the identification of the dominant epidemiological cycle of tuf b and field bindweed [ 9 ].…”

“…Using sequence analysis, new tuf type variants associated with the nettle and called tuf b2 [ 9 , 10 ] or tuf ab [ 11 , 12 ], were recently detected in vineyards in Austria, Macedonia, Croatia and Montenegro. Additionally, tuf b3 variant was reported in vineyards in the Republic of Azerbaijan [ 13 ] and formerly detected in a diseased potato plant collected in Romania [ 14 , 15 ].…”