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Bianco, Piero Attilio; Mehle, Natasa; Loiseau, Marianne; Ferretti, Luca; Abou Jawdah, Yusuf; Siampour, Majid; Shneyder, Yuri
‘Candidatus Phytoplasma phoenicium’ (‘Ca. P. phoenicium’) strains are members of the phytoplasma’s subgroup 16SrIX-B and its variants (Quaglino et al., 2015). These strains are the etiological agents of a lethal disease of almond trees (Prunus dulcis). Peach (P. persica) and nectarine (P. persica var. nucipersica) may also be seriously affected by ‘Ca. P. phoenicium’ (Jawhari et al., 2015). The common name of the disease is almond witches’-broom (AlmWB). Although ‘Ca. P. phoenicium’ infection occurs mainly in almond, peach, and nectarine, it has also been occasionally identified in P. armeniaca (apricot), Prunus x amygdalo-persica (main rootstock for almond and peach in Europe), and in wild plants such as P. orientalis, P. scoparia, Anhemis spp., Smilax aspera (Fiore et al., 2018). ‘Ca. P. phoenicium’ is reported from Lebanon and Iran where it is widespread where Prunus hosts are grown. Recently, ‘Ca. P. phoenicium’ has also been detected on almond plants in southeast Italy (Nigro et al., 2019). Early detection is an essential measure to survey the presence and to avoid the introduction and spread of the pathogens into free areas. Detection methods for ‘Ca. P. phoenicium’ have been developed and include conventional and real-time polymerase chain reaction. The DIPCAPP project contributed to identify the most suitable protocol for the detection of ‘Ca. P. phoenicium’. Among six already published and evaluated tests, four showed excellent specificity, sensibility, accuracy, and reproducibility and were equally effective in detecting ‘Ca. P. phoenicium’. From the results of the comparison carried out in the project, it appeared that the conventional PCR from Jawhari, et al., (2015) and the real-time PCR from Jawhari, et al., (2015) are the best methods for the detection of the pathogen, also considering the limited time and labour requested for their execution.