Identification of four distinct ‘Candidatus Phytoplasma’ species in pomegranate trees showing witches' broom, little leaf and yellowing in Jordan, and preliminary insights on their putative insect vectors and reservoir plants

Abstract

During field surveys conducted in northern Jordan from June to November 2020, phytoplasma‐like symptoms, including leaf yellowing/reddening and rolling, little leaf and witches' broom were observed in pomegranate. Disease incidence in 22 surveyed orchards ranged from 30% to 65%. Nested PCR‐based amplification of 16S rRNA gene detected phytoplasmas in 17% of collected symptomatic pomegranate trees. Amplicon nucleotide sequence analyses allowed attributing the detected phytoplasmas to ‘Candidatus Phytoplasma solani’, ‘Ca. P. aurantifolia’, ‘Ca. P. asteris’ and ‘Ca. P. ulmi’. These phytoplasmas were found in plants showing specific symptoms and differentially distributed in the considered locations. Additionally, three cicadellids (Macrosteles sexnotatus, Cicadulina bipunctata and Psammotettix striatus) and two non‐crop plants (Plantago major and Capsicum annuum) resulted hosting ‘Ca. P. asteris’ strains, and one cicadellid (Balclutha incisa) was carrying a ‘Ca. P. solani’ strain. A new pomegranate disease complex associated with multiple phytoplasmas, including ‘Ca. P. aurantifolia’ and ‘Ca. P. ulmi’, never reported before in this host plant, is described here. Moreover, preliminary indications are provided on its possible epidemiology in Jordan, involving two putative insect vectors (M. sexnotatus, B. incisa) first reported in the Country.

Identification of phytoplasmas in stone fruit (Prunus sp.) and persimmon (Diospyros kaki L.) trees exhibiting leaf alterations and witches'‐broom in Jordan

“…Remarkably, ‘ Candidatus Phytoplasma’ species identified in symptomatic stone fruit and persimmon trees were previously reported in Jordan in association with diseases of other important crops (grapevine, plum, peach) (Abu Alloush, Bianco, Amashah, Busato, et al., 2023; Abu Alloush, Bianco, Busato, Alkhawaldeh, et al., 2023; Abu Alloush, Bianco, Busato, AlMahasneh, et al., 2023; Anfoka & Fattash, 2004; Salem et al., 2013, 2020). Moreover, this is the first study reporting sweet cherry and persimmon infection by ‘ Ca .…”