First report of ‘Candidatus Liberibacter solanacearum’ on carrot and parsley in Turkey

In August 2020, diseased and asymptomatic carrot (Daucus carota) and parsley (Petroselinum crispum) plants were collected from eight different fields in Beypazari, near Ankara in Central Anatolia, Turkey. While carrot plants exhibited symptoms of purpling of leaves and hairy secondary root formation (Figure 1), on parsley plants only yellowing of the leaves was observed (Figures 2–3). Symptoms on carrots were similar to those associated with phytoplasmas or ‘Candidatus Liberibacter solanacearum’ (CaLso).

FIGURE 1. Diseased carrot field showing purpling of leaves, in Beypazari, Turkey

FIGURE 2. Diseased parsley field showing leaf yellowing, in Beypazari, Turkey

FIGURE 3. Diseased (right) and asymptomatic (left) parsley harvested field, in Beypazari, Turkey

In total, 11 carrots (six diseased and five asymptomatic) and two parsley (one diseased and one asymptomatic) plants were analysed by real-time PCR (qPCR) using primers designed from the 16S ribosomal RNA (rRNA) gene of CaLso according to Li et al. (2009). Total genomic DNA was extracted from petioles using a DNeasy Plant Mini Kit (Qiagen, Germany). CaLso was detected in all samples from diseased plants (six carrots, one parsley) with cycle threshold values ranging from 25.1 to 28.28. The bacterium was not detected in the asymptomatic plants. All CaLso qPCR-positive samples were confirmed by conventional PCR using CL514F/R primers, which amplify a 669 bp fragment of the rpIJ/rpIL 50S rRNA ribosomal protein genes, and Sanger sequencing of the PCR product (Munyaneza et al., 2009). BLAST analysis of the rpIJ/rpIL nucleotide sequences of one parsley (GenBank Accession No. MZ772928), and two representative carrots (ON012206, ON012207) were identical and showed 100% identity with sequences of several CaLso isolates from the Mediterranean region (MG657027 from Israel; KY595980 from Greece; HQ454305.1, HQ454310, HQ454311, HQ454317 HQ454321, from Spain; KY753132 from Tunisia), some of which were identified as “haplotype D”. Carrot, celery, fennel, parsley and parsnip are all hosts of CaLso from the Apiaceae family, which have been recorded in several European countries (European and Mediterranean Plant Protection Organization, 2022). Phytoplasmas were not detected in any carrot or parsley samples using qPCR (Christensen et al., 2004; Christensen et al., 2013).

To our knowledge, this is the first report of ‘Candidatus Liberibacter solanacearum’ on carrot and parsley in Turkey. To better understand the establishment and distribution of CaLso in Turkey, there is a need for further surveillance in cultivated apiaceous plants, in weeds and vectors.

ACKNOWLEDGEMENTS

We thank The Republic of Turkey's Ministry of Agriculture and Forestry, General Directorate of Agricultural Research and Policies for funding this project carried out under EUPHRESCO research topic “Epidemiology and diagnosis of potato phytoplasmas and ‘Candidatus Liberibacter solanacearum’ and their contribution to risk management”.