First Report of “Candidatus Liberibacter solanacearum” Associated with Psyllid-Affected Carrots in Norway

Abstract

Carrot (Daucus carota) plants with symptoms resembling those associated with the carrot psyllid Trioza apicalis and the bacterium “Candidatus Liberibacter solanacearum” (1–4) were observed in 70 to 80% of commercial fields and experimental plots in southeastern Norway from late July to mid-September of 2011; all cultivars grown were affected with approximately 10 to 100% symptomatic plants per field. T. apicalis, a pest of carrot in northern and central Europe, including Norway, can cause as much as 100% crop loss and is associated with “Ca. L. solanacearum” (1–4). Symptoms on affected plants include leaf curling, yellow and purple discoloration of leaves, stunted growth of shoots and roots, and proliferation of secondary roots. Carrot plant samples were collected from five T. apicalis-infested fields in Ostfold, Vestfold, Oppland, and Hedmark counties. Total DNA was extracted from petiole and root tissues of 54 plants, including 27 symptomatic plants and 27 asymptomatic plants from four cultivars (Namdal, Panther, Romance, and Yukon) with the cetyltrimethylammonium bromide (CTAB) buffer extraction method (2,3). DNA samples were tested by PCR assay using primer pairs OA2/OI2c and CL514F/R to amplify a portion of 16S rDNA and rplJ/rplL ribosomal protein genes, respectively, of “Ca. L. solanacearum” (2,3). A 1,168-bp 16S rDNA fragment was detected in the DNA from 22 (81.5%) symptomatic plants and a 668-bp rplJ/rplL fragment was amplified from the DNA of 26 (96.3%) symptomatic and 5 (18.5%) asymptomatic plants, indicating the presence of liberibacter. No liberibacter was detected in the asymptomatic carrot plants with the primer pair OA2/OI2c. Amplicons from the DNA of four carrot root samples with each primer pair were cloned (pCR2.1-TOPO; Invitrogen, Carlsbad, CA) and three clones of each of the eight amplicons were sequenced (MCLAB, San Francisco, CA). BLAST analysis of the 16S rDNA consensus sequence from the carrot root tissues (GenBank Accession No. JN863097) showed 100% identity to those of “Ca. L. solanacearum” previously amplified from carrot (GU373048 and GU373049) and T. apicalis (GU477254 and GU477255) in Finland (2,3). The rplJ/rplL consensus sequence from the carrots (GenBank Accession No. JN863098) was 99% identical to the sequences of rplJ/rplL “Ca. L. solanacearum” ribosomal protein gene from carrots in Finland (GU373050 and GU373051). To our knowledge, this is the first report of “Ca. L. solanacearum” associated with carrot in Norway. This bacterial species has caused millions of dollars in losses to potato and several other solanaceous crops in North and Central America and New Zealand (1). This plant pathogen has also been reported from carrots and T. apicalis in Finland, where it has caused significant economic damage to carrot crops (2–4). References: (1) J. E. Munyaneza. Southwest. Entomol. 35:471, 2010. (2) J. E. Munyaneza et al. Plant Dis. 94:639, 2010. (3) J. E. Munyaneza et al. J. Econ. Entomol. 103:1060, 2010. (4) A. Nissinen et al. Entomol. Exp. Appl. 125:277, 2007.

Leafhopper and Psyllid Pests of Potato

“…This temperature is very similar to the preferred optimum temperature (27°C) for potato psyllid reproduction and liberibacter development (Munyaneza 2010b). Very recently, Munyaneza et al (2010dMunyaneza et al ( , 2010e, 2011aMunyaneza et al ( , 2012bMunyaneza et al ( , 2012c detected "Ca. data).…”

“…data). Damage to carrots by liberibacter-infected carrot psyllids can cause up to 100% crop loss if the psyllid is not controlled (Munyaneza et al 2010d(Munyaneza et al , 2010e, 2012b(Munyaneza et al , 2012c. L. solanacearum" in carrots attacked by the psyllid Trioza apicalis in Finland, Sweden, and Norway.…”

‘Candidatus Liberibacter solanacearum’

“…L. solanacearum’ has been detected in carrot plants ( Daucus carota ) in Finland and is vectored by the carrot psyllid, Trioza apicalis Förster (Munyaneza et al ., ,b, ). Subsequently, this bacterium was also detected in carrots and T. apicalis in Sweden and Norway (Munyaneza et al ., ,c). Most recently, ‘ Ca .…”

“…Symptoms in carrots infected with ‘ Ca . L. solanacearum’ include leaf curling, yellowish, bronze and purplish discoloration of leaves, stunting of the carrot shoots and roots, and proliferation of secondary roots (Munyaneza et al ., ,b, ,c; Alfaro‐Fernández et al ., ,b). Collectively, these symptoms resemble those caused by leafhopper‐transmitted phytoplasmas and S. citri in carrots (Font et al ., ; Lee et al ., ; Cebrián et al ., ; Munyaneza et al ., ).…”

“…The complex bacterium/vectors has caused serious damage to the potato and tomato industries in the Americas and New Zealand (Munyaneza et al ., ,b, ; Liefting et al ., ; Secor et al ., ; Crosslin et al ., ; Rehman et al ., ; Guenthner et al ., ) and to the carrot industry in Europe (Munyaneza, ; Munyaneza et al ., ,b, ,c; Alfaro‐Fernández et al ., ,b). In the case of potato, plant growth is negatively affected; crisps or chips made from zebra chip‐infected tubers show dark stripes that become markedly more visible upon frying, and hence are commercially unacceptable.…”