Molecular study of two distinct phytoplasma species associated with streak yellows of date palm in Iran

Abstract

A disease with symptoms similar to palm lethal yellowing was noticed in the early 2013 in Khuzestan Province (Iran) in date palm (Phoenix dactylifera). Infected trees displaying symptoms of streak yellows and varied in the incidence and severity of yellowing. A study was initiated to determine whether phytoplasma was the causal agent. Polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) methods using universal phytoplasma primers pairs R16mF1/mR1 and M1/M2 were employed to detect putative phytoplasma(s) associated with date palm trees. Nested PCR using universal primers revealed that 40 out of 53 trees were positive for phytoplasma while asymptomatic date palms from another location (controls) tested negative. RFLP analyses and DNA sequencing of 16S rDNA indicated that the presence of two different phytoplasmas most closely related to clover proliferation (CP) phytoplasma (group 16SrVI) and ash yellows (AY) phytoplasma (group 16SrVII). Sequence analysis confirmed that palm streak yellows phytoplasmas in each group were uniform and to be phylogenetically closest to “CandidatusP. fraxini” (MF374755) and “Ca. P. trifolii” isolate Rus‐CP361Fc1 (KX773529). Result of RFLP analysis of secA gene of positive samples using TruI and TaqI endonuclease is in agreement with rDNA analysis. On this basis, both strains were classified as members of subgroups 16SrVI‐A and 16SrVII‐A. This is the first report of a phytoplasma related to CP and AY phytoplasma causing date palm yellows disease symptoms.

History and Current Status of Phytoplasma Diseases in the Middle East

“…The latter is the only record of the 16SrIV group in the Middle East. Recently, the association between 16SrVI and 16SrVII and date palms has been reported in Iran [ 110 ], while the 16SrII-D subgroup has been reported to be associated with date palm streak yellows in Oman [ 111 ].…”

Molecular detection and identification of phytoplasmas associated with Catharanthus roseus, Pinus eldarica, and Petunia hybrida in southeastern Iran's urban green spaces

“…P. trifolii' (16SrVI-A subgroup) and 'Ca. aurantifolia' (16SrII-D subgroup) have been identified as infecting periwinkles on the Caspian coast in the north (Mazandaran province) (Fattahi et al, 2016) and southeastern Iran (Siampour, Izadpanah, Martini, & Salehi, 2019) Ghayeb Zamharir & Eslahi, 2019).…”

Molecular detection and characterization of a 16SrII-D phytoplasma associated with streak yellows of date palm in Oman

“…White tip die-back displaying severe chlorosis of the new leaves, white longitudinal streaks of the midribs, and drying/ whiteness of the crown has been reported to be associated with 16SrXIV in Sudan (Cronjé et al 2000). However, the characteristic streak yellowing of leaves has been reported in Iran (Zamharir and Eslahi 2019). This is the first report of association of 16SrII-D with date palm in Oman.…”

“…Phytoplasmas are known to cause major diseases in palms, including the lethal yellowing disease (Gurr et al 2016). Several reports are available on the association between diverse phytoplasma groups and date palms, including the 16SrI in Egypt (Alkhazindar 2014), 16SrII in Saudi Arabia (Alhudaib et al 2007), 16SrIV in the USA (Ntushelo et al 2012), 16SrVI and VII in Iran (Zamharir and Eslahi 2019) and 16Sr XIV in Sudan (Cronjé et al 2000). The most known symptoms included yellowing and streak yellows in leaves, while in some regions lethal yellowing symptoms have been observed.…”