Occurrence, Molecular Characterization and Vector Transmission of a Phytoplasma Associated with Rapeseed Phyllody in Iran

Hosseini

2018

New Disease Reports

Common sowthistle (Sonchus oleraceus) is a major weed problem in Iran and is also used for medicinal purposes. During 2012-2015 surveys of Fars and Yazd provinces (Iran) for phytoplasma diseases, a phyllody disease was observed in S. oleraceus plants growing as weeds within and/or in the surroundings of fields and orchards. The main symptoms of the disease were yellowing and reddening of leaves, shortened internodes, flower virescence, phyllody, proliferation and witches' broom ( Fig. 1).Total DNA was extracted from 0.2 g of leaf midribs of eight symptomatic (four plants per province) and four symptomless (collected in Fars province) S. oleraceus plants using the CTAB method of Zhang et al. (1998). DNA samples were tested for phytoplasma presence by a nested PCR assay primed by primer pairs P1/P7 followed by R16F2n/R16R2 (Lee et al., 1998). Amplicons of~1.25 kb were obtained in the nested round from all eight diseased plants but not from the four symptomless plants. Eight nested amplicons were separately cloned and sequenced. The obtained sequences were identical and a consensus sequence corresponding to the Abarkooh (Yazd Province, Iran) S. oleraceus phyllody phytoplasma was deposited in GenBank (Accession No. MG652627). The S. oleraceus phyllody phytoplasma strain had 99.78% sequence identity with the 'Ca. P. asteris' reference strain (M30790). A BLAST search showed that this sequence had maximum identity (99-100%) with members of the 16SrI subgroup B. Phylogenetic analysis using the neighbour-joining method (MEGA7) (Fig. 2) showed that the Abarkooh S. oleraceus phyllody phytoplasma was clustered within the 16SrI group closest to onion yellows phytoplasma (NC_005303), representative of subgroup 16SrI-B.A 16SrI-A phytoplasma has been previously reported in S. oleraceus in Canada (Khadhair et al., 2008), however to our knowledge this is the first report of a 16SrI-B phytoplasma associated with S. oleraceus phyllody disease. The occurrence of 16SrI-B phytoplasma strains were previously reported in Iran on Brassica napus (Salehi et al., 2011), Eruca sativa (Esmailzadeh Hosseini et al., 2017) and Eucalyptus camaldulensis (Salehi et al., 2016); S. oleraceus may act as a reservoir host. References

mentioning

confidence: 76%

First report of a ‘Candidatus Phytoplasma asteris‘‐related strain (16SrI‐B) associated with Sonchus oleraceus (common sowthistle) phyllody disease in Iran

Hosseini

2018

New Disease Reports

“…Ct can also transmit strains of 'Candidatus Phytoplasma trifolii', and Ch can transmit a strain of 'Ca. P. asteris' Salehi et al, 2010). All these phloem-limited bacteria colonise their insect vectors after an acquisition access period and are transmitted in a persistent manner over the lifespan of the insect but are not transmitted transovarially (Liu et al, 1983;Weintraub and Beanland, 2006).…”

Section: Biology Of C Haematoceps and C Tenellusmentioning

confidence: 99%

“…The transmission of an Iranian strain of 'Candidatus Phytoplasma asteris' responsible for the phyllody of rapeseed disease (Brassica rapa) by Ct has been reported in Iran (Salehi et al, 2010). This phytoplasma is widespread in Europe but different leafhopper vectors have been reported in Europe (Lee et al, 2004;Weintraub and Beanland, 2006).…”

Section: 23mentioning

confidence: 99%

See 1 more Smart Citation

Scientific Opinion on the pest categorisation of Circulifer haematoceps and C. tenellus

Rossi¹

2015

EFS2

The Panel on Plant Health performed a pest categorisation of Circulifer tenellus (Ct) and C. haematoceps (Ch) (Hemiptera, Cicadellidae) for the European Union (EU) territory. They are well-defined insect species that can be identified on the basis of external morphology and male genitalia. Ch and Ct are considered to originate from the Old World; Ct is also present in North America and the Caribbean. In the EU, Ch is reported in 11 Member States, mostly in southern or central Europe, and Ct is reported in Spain, France, Italy and Greece. Neither species is harmful by itself, but they are vectors of Spiroplasma citri, the causal agent of, for example, citrus stubborn disease. The major impact of Ct in North America results from the transmission of Beet curly top virus to sugarbeet. Ct also transmits 'Candidatus Phytoplasma trifolii' and Ch transmits 'Ca P. asteris'. There is no transovarial transmission of the pathogens. Ch and Ct are regulated harmful organisms in the EU and listed in Annex II, Part A, Section II, of Council Directive 2000/29/EC together with Spiroplasma citri and with respect to plants of Citrus, Fortunella, Poncirus and their hybrids, other than fruit and seeds, despite the fact that Ct and Ch have a larger host range. Ch and Ct are likely to be disseminated by plants for planting (the eggs are laid into the leaf veins and petioles), they have also been observed to hitch-hike on terrestrial vehicles, and Ct is known for its very high flight capacity. Both species have many hosts, in particular in the Chenopodiaceae, Brassicaceae and Asteraceae. Ecological conditions in the risk assessment area are suitable for the establishment and spread of S. citri, at least where citrus is currently grown.

“…In nested PCR, P1/P7 amplicons diluted 1: 30 in sterile distilled water were re-amplified with the internal primer pair R16F2n/R16R2 (Gundersen and Lee, 1996) which amplifies about 1,250 bp of 16S rRNA gene. PCR conditions were as described previously (Salehi et al, 2011). PCR products were electrophoresed in 1% agarose gels in TAE buffer and visualized with a UV transilluminator following ethidium bromide staining.…”

mentioning

confidence: 99%

Identification of a phytoplasma associated with pomegranate little leaf disease in Iran

et al. 2016

Self Cite

a b s t r a c tDuring 2012e2014 surveys for the presence of phytoplasma diseases in Fars province (Iran), pomegranate little leaf symptoms were observed in several orchards in Khafr and Neyriz areas. Samples collected from symptomatic plants positively reacted in nested PCR assays using P1/P7 followed by R16F2n/R16R2 primer pairs producing the expected 1,250 bp DNA fragments. Real and virtual RFLP analysis showed that the sequences of phytoplasma strains from Khafr and Neyriz (KPLL and NPLL strains, respectively) were identical to each other and belong to 16SrII phytoplasma group, subgroup D. Phylogenetic analysis of the R16F2n⁄R16R2 DNA region confirmed that KPLL and NPLL phytoplasmas were enclosed in the same clade as other 16SrII-D subgroup phytoplasmas. This is the first reported occurrence of a 16SrII phytoplasma infecting pomegranate trees.