Abstract Field surveys were conducted in wine and table grape vineyards from June to October 2020 in 13 locations belonging to five governorates in North and South Jordan. Typical grapevine yellows ...symptoms, including leaf reddening/yellowing and rolling were observed on 10% to 55% of vines. Nested PCR‐based amplification of the 16S rRNA gene detected phytoplasmas in 22% and 15.7% of the analysed symptomatic wine and table grape cultivar plants, respectively. Amplicon nucleotide sequence analyses identified the detected phytoplasmas as “ Candidatus Phytoplasma solani” (taxonomic subgroup 16SrXII‐A), “ Ca . P. omanense” (16SrXXIX‐A and ‐B), “ Ca . P. aurantifolia” (16SrII‐C) and “ Ca . P. asteris” (16SrI‐R) in 72.4%, 17.2%, 6.9% and 3.4% of infected plants, respectively. Such phytoplasmas were found differentially distributed in wine and table grape cultivar vineyards surveyed. Further investigation identified “ Ca . P. solani” in the putative insect vectors Orosius cellulosus (first report in Jordan), Euscelidius mundus , Laodelphax striatellus , and Circulifer sp., and in bindweed; “ Ca . P. aurantifolia” in the insect O. cellulosus and in bindweed; “ Ca . P. omanense” in the insect Psammotettix striatus ; and “ Ca . P. asteris” in the insects Arboridia adanae , Cicadulina bipunctata , Circulifer sp., L. striatellus , Hyalesthes obsoletus , and P. striatus . Based on this preliminary data, ecological cycles of such phytoplasmas are discussed. Results suggest that the diversity and ecology of grapevine yellows phytoplasmas in Jordan are more complex than previously known, leading to a potential risk of disease outbreaks.
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.
PCR‐based amplification and sequence analyses of 16S rRNA gene detected ‘Candidatus Phytoplasma solani’, ‘Ca. P. aurantifolia’, ‘Ca. P. asteris’ and ‘Ca. P. ulmi’ in pomegranate trees showing phytoplasma‐like symptoms (leaf yellowing/reddening and rolling, little leaf and witches' broom) in Jordan. 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. Further studies are needed to verify the diffusion of pomegranate phytoplasma‐associated diseases in the region and demonstrate the transmission capability of the identified phytoplasma positive insects.
During field surveys conducted in 2020 in Jordanian orchards, phytoplasma‐like symptoms (leaf yellowing/reddening and rolling, and witches'‐broom) were observed in three stone fruit species (peach, ...European plum, sweet cherry) and persimmon. Molecular analyses identified phytoplasma strains belonging to the species ‘Candidatus Phytoplasma solani’ (subgroup 16SrXII‐A) as largely prevalent in stone fruit and persimmon symptomatic plants. Moreover, ‘Ca. Phytoplasma omanense’ (16SrXXIX‐B) was found in few European plum symptomatic plants. In previous studies, such phytoplasma strains were identified in other important crops (almond, pomegranate, and grapevine) and in several putative insect vectors, suggesting their complex ecology in Jordan. Further studies are needed to in‐depth investigate the diffusion of phytoplasma‐associated diseases of stone fruits throughout the Country, to clarify their aetiology, and to study their epidemiological pattern(s).
During field surveys carried out from June to October 2020 and in January 2021 in orchards of northern Jordan, phytoplasma-like symptoms (early flowering along with evergreen pattern; witches’-broom, ...yellowing, and dieback; slim leaf and leaf rolling; stem fasciation) were observed in almond trees. In 23 investigated orchards, symptomatic almond trees ranged from 20 to 85%. PCR-based amplification of 16S rRNA gene detected phytoplasmas in 21% of 140 collected symptomatic almond trees. Sequence analyses allowed attributing the detected phytoplasmas to ‘Candidatus Phytoplasma asteris’ (taxonomic subgroups 16SrI-B and -R), ‘Ca. P. aurantifolia’ (16SrII-B and -C), ‘Ca. P. omanense’ (16SrXXIX-A and -B), ‘Ca. P. phoenicium’ (16SrIX-B), ‘Ca. P. pyri’ (16SrX-C), ‘Ca. P. solani’ (16SrXII-A), and ‘Ca. P. ulmi’ (16SrV-A). Such phytoplasmas were found associated with specific symptoms and differentially distributed in the considered locations. Moreover, further investigation identified ‘Ca. P. asteris’ (subgroup 16SrI-R) in putative insect vectors such as Empoasca sp., Reptalus sp., and Hyalesthes obsoletus, ‘Ca. P. pyri’ in Cacopsylla bidens, and ‘Ca. P. omanense’ (subgroup 16SrXXIX-B) in the non-crop plant Amaranthus sp. In conclusion, this study described an almond disease complex associated with multiple phytoplasmas, including ‘Ca. P. pyri’, ‘Ca. P. omanense’, and ‘Ca. P. ulmi’ that were never reported before in this crop. Further studies are needed to survey the diffusion of this almond disease complex in the region, demonstrate the transmission capability of the identified putative vectors, and in-depth investigate the ecologies of all phytoplasmas associated with the disease.
•Seven ʻCandidatus Phytoplasmaʼ species were reported in Jordan in association with an almond disease complex.•ʻCa. P. omanenseʼ, ʻCa. P. ulmi’, and ʻCa. P. pyriʼ were firstly reported in almond around the world.•New subgroup XXIX-B was described.•Eight insect taxa were found positive to ʻCa. Phytoplasma pyriʼ and ʻCa. P. asterisʼ.
During field surveys conducted in 2021 in western Jordanian heights, phytoplasma-like symptoms were observed, including leaf reddening along with slow decline in pear (pear decline symptoms) and leaf ...yellowing followed by scorch in apple trees. Abundant populations of the psyllid
Cacopsylla bidens
were found in the pear trees. Nested PCR amplifying 16S rDNA detected phytoplasmas in 63% and 36% of symptomatic pear and apple samples, respectively, and in 46% of pooled
C. bidens
specimens. No phytoplasmas were detected in symptomless plant samples. PCR product nucleotide sequence analyses attributed the phytoplasmas detected in pear to ‘
Candidatus
Phytoplasma pyri’, ‘
Ca
. P. solani’, ‘
Ca
. P. omanense’, and ‘
Ca
. P. aurantifolia’, and those identified in apple to ‘
Ca
. P. solani’ and ‘
Ca
. P. omanense’. All phytoplasma strains identified in
C. bidens
were attributed to ‘
Ca.
P. pyri’. To the best of our knowledge, this is the first report of phytoplasmas associated with pear and apple diseases, including pear decline, in Jordan. Even though a limited number of pome fruit samples were analyzed, a surprising diversity was found among detected phytoplasmas. Further studies will be carried out to investigate the complex etiology of such diseases, and the ‘
Ca
. P. pyri’ vectoring activity of
C. bidens
.
