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4891

Symptoms of abnormal proliferation of shoots resulting in formation of witches’-broom growths were observed on diseased plants of passion fruit (Passiflora edulis f. flavicarpa Deg.) in Brazil. RFLP analysis of 16S rRNA gene sequences amplified in PCRs containing template DNAs extracted from diseased plants collected in Bonito (Pernambuco) and Viçosa (Minas Gerais) Brazil, indicated that such symptoms were associated with infections by two mutually distinct phytoplasmas. One phytoplasma, PassWB-Br4 from Bonito, represents a new subgroup, 16SrIII-V, in the X-disease phytoplasma group (‘Candidatus Phytoplasma pruni’-related strains). The second phytoplasma, PassWB-Br3 from Viçosa, represents a previously undescribed subgroup in group 16SrVI. Phylogenetic analyses of 16S rRNA gene sequences were consistent with the hypothesis that strain PassWB-Br3 is distinct from previously described ‘Ca. Phytoplasma ’ species. Nucleotide sequence alignments revealed that strain PassWB-Br3 shared less than 97.5 % 16S rRNA gene sequence similarity with previously described ‘Ca. Phytoplasma ’ species. The unique properties of its DNA, in addition to natural host and geographical occurrence, support the recognition of strain PassWB-Br3 as a representative of a novel taxon, ‘Candidatus Phytoplasma sudamericanum’.

In September 2011, potato (Solanum tuberosum L.) tubers graded in a packing facility in south-central Idaho were observed with internal discolorations suggestive of zebra chip disease (ZC). Symptoms were observed in 1 to 2% of tubers of cv. Russet Norkotah and included brown spots and streaks especially in and near the vascular tissue. Some tubers also showed a dark and sunken stolon attachment typical of ZC (1). Initially, tissue samples were taken from seven symptomatic tubers and tested by PCR for “Candidatus Liberibacter solanacearum”, the bacterium associated with ZC. Primers specific for the 16S rDNA (primers CLipoF [4] and OI2c [3]) and the outer membrane protein (OMB 1482f and 2086r) (2) were used. Six of these samples were positive for the bacterium. The amplified 16S rDNA and OMB products from two symptomatic tubers of cv. Russet Norkotah were cloned and three clones of each were sequenced. The 16S sequences (1,071 bp; GenBank Accession Nos. JN848755 and JN848756) from the two tubers varied by one nucleotide and had 99 to 100% sequence identity to numerous “Ca. L. solanacearum” sequences in GenBank (e.g., Accession Nos. HM246509, FJ957897, and EU935004). Sequences of the two OMB clones (605 bp; GenBank Accession Nos. JN848757 and JN848758) had 97% sequence identity to the two “Ca. L. solanacearum” OMB sequences in GenBank (Accession Nos. CP002371 and FJ914617). Six of eight additional symptomatic field-collected cv. Russet Norkotah tubers corresponding to tubers collected in the packing facility were also positive for “Ca. L. solanacearum” by PCR. Additional severely symptomatic tubers of cvs. Russet Burbank, Yukon Gold, and raw cut French fries of Ranger Russet produced in south-central Idaho were subsequently tested by PCR and were found to be positive for “Ca. L. solanacearum” as well. On the basis of the symptoms, specific PCR amplification with two distinct primer pairs and DNA sequence analysis, zebra chip disease caused by “Ca. L. solanacearum” was determined to be present in Idaho. This disease has caused significant economic damage to potatoes in many regions, including Texas, Mexico, Central America, and New Zealand (1). Idaho is the largest potato-producing state in the United States, with over 150,000 ha planted this year, and therefore, ZC potentially poses a significant risk to agriculture in this state. References: (1) J. M. Crosslin et al. Online publication. doi:10.1094/PHP-2010-0317-01-RV, Plant Health Progress, 2010. (2) J. M. Crosslin et al. Southwest. Entomol. 36:125, 2011. (3) S. Jagoueix et al. Mol. Cell. Probes 10:43, 1996. (4) G. A. Secor. Plant Dis. 93:574, 2009.

ABSTRACT To estimate the likelihood of people coming into contact with the recently described tick-borne agent “ Candidatus Neoehrlichia mikurensis,” we compared its prevalence to those of Lyme disease spirochetes and Anaplasma phagocytophilum in questing adult Ixodes ricinus ticks collected in various Central European sites and examined ticks, which had been removed from people, for the presence of these pathogens. Whereas spirochetes infected questing adult ticks most frequently (22.3%), fewer than a third as many ticks were infected by “ Ca . Neoehrlichia mikurensis” (6.2%), and about a sixth harbored A. phagocytophilum (3.9%). On average, every twelfth encounter of a person with an I. ricinus tick (8.1%) may bear the risk of acquiring “ Ca . Neoehrlichia mikurensis.” Although a fifth of the people (20%) had removed at least one tick infected by “ Ca . Neoehrlichia mikurensis,” none displayed symptoms described for this pathogen, suggesting that its transmission may not be immediate and/or that immunocompetent individuals may not be affected. Because immunosuppressed patients may be at a particular risk of developing symptoms, it should be considered that “ Ca . Neoehrlichia mikurensis” appears to be the second most common pathogen in I. ricinus ticks. In our survey, only Borrelia afzelii appears to infect Central European vector ticks more frequently.