02603nas a2200277 4500008004100000022001400041245015200055210006900207260001200276300001400288490000700302520177700309653001602086653001202102653001302114653002002127653001402147653002702161100001602188700001602204700002002220700001702240700001502257700001302272856004002285 2013 eng d a1365-305900aPhytophthora acerina sp. nov., a new species causing bleeding cankers and dieback of Acer pseudoplatanus trees in planted forests in northern Italy0 aPhytophthora acerina sp nov a new species causing bleeding canke c08/2014 a858–8760 v633 a

A severe dieback of Acer pseudoplatanus trees was noticed in planted forest stands in northern Italy in 2010. Affected trees showed collar rot and aerial bleeding cankers along the stems, leading to crown dieback and eventually death. An unknown Phytophthora species was consistently isolated from necrotic bark and xylem tissue and from rhizosphere soil. Based on its unique combination of morphological and physiological characters and phylogenetic analysis, this new taxon is here described as Phytophthora acerina sp. nov. Phylogenetic analysis of ITS, cox1 and β-tubulin gene regions demonstrated that P. acerina is unique and forms a separate cluster within the ‘P. citricola complex’, closely related to P. plurivora. Phytophthora acerina is homothallic with smooth-walled oogonia, thick-walled, mostly aplerotic oospores with a high abortion rate, paragynous antheridia, and persistent, morphologically variable semipapillate sporangia. Four to 5-week-old cultures produced globose to subglobose, appressoria-like and coralloid hyphal swellings and characteristic stromata-like hyphal aggregations. Optimum and maximum temperatures for growth are 25°C and 32°C, respectively. Genetic uniformity of all 15 studied isolates and the apparent absence of this species in the extensive surveys of nurseries, forests and seminatural ecosystems conducted in the previous two decades across Europe indicate a recent clonal introduction to northern Italy. Under-bark inoculation tests demonstrated high aggressiveness of P. acerina to A. pseudoplatanus indicating that this pathogen might be a serious risk to maple plantations and forests in Europe.

10abiosecurity10aClade 210ainvasive10anursery pathway10aphylogeny10aPhytophthora citricola1 aGinetti, B.1 aMoricca, S.1 aSquires, J., N.1 aCooke, D E L1 aRagazzi, A1 aJung, T. uhttp://dx.doi.org/10.1111/ppa.1215304151nas a2200181 4500008004100000022001400041245011100055210006900166260001600235300001600251490000700267520356300274100001603837700001903853700001503872700001603887856006603903 2014 eng d a0191-291700aPhytophthoraTaxon Pgchlamydo is a Cause of Shoot Blight and Root and Collar Rot of Viburnum tinus in Italy0 aPhytophthoraTaxon Pgchlamydo is a Cause of Shoot Blight and Root cJan-10-2014 a1432 - 14320 v983 a

The quarantine pathogen Phytophthora ramorum has recently been found on dying Viburnum tinus in the nursery area of Pistoia, central Italy (43°56′0″ N, 11°1′0″ E) (3). As part of a surveillance program aimed at detecting P. ramorum in this area, the Phytophthora taxon Pgchlamydo was consistently found associated with symptomatic V. tinus. The crowns of these plants were wilted, and some plants also showed root and collar rot and underbark necrosis. Water courses adjacent to the nursery with the infected V. tinus were tested for the pathogen. Samples from seven symptomatic plants were placed on a selective V8A-PARPNH medium within 24 h from sampling. Tissue pieces (2 mm2) of 12 baits (apple fruits) exposed for a week in water bodies were plated on the same medium. Cottony colonies arose after 2 to 3 days of incubation at 23°C in the dark and were transferred to potato dextrose agar (PDA) in purity. Mycelial DNA was extracted with a commercial kit (Sigma-Aldrich). The rDNA ITS region and a portion of the mtDNA cox1 gene were PCR-amplified and the amplicons digested with the restriction enzymes MspI and AluI (for the ITS region) and RsaI (for the cox1 gene region). Isolates R7 from V. tinus, and ES2M5, ES2M11, and ES1M12 from the water bodies belonged to the same taxon based on restriction analysis of both DNA regions coupled with ITS-rDNA sequence homology (GenBank Accession Nos. KJ396773 to 76). A BLAST search in GenBank found that all isolates had a 99% identity in the ITS-rDNA with the Phytophthora ITS Clade 6 member P. taxon Pgchlamydo. Sporangia produced after incubation in filtered pond water for 24 h were mostly ovoid (sometimes obpyriform), non-papillate, non-caducous. Some sporangia were emptied with external proliferation and had hyphal swellings. Thirty sporangia were measured and averaged 42.4 ± 6.2 × 29.9 ± 3.5 μm (range 30.0 to 56.1 × 22.5 to 38.0), with a length/width ratio of 1.4 ± 0.2 (1.2 to 2.0), and exit pores of 11.7 ± 1.5 μm (9.0 to 14.6). Optimum colony growth on V8A at 30°C was 4.4 ± 0.4 mm day–1, and the maximum temperature for growth was 32°C. Inoculation on twigs of Fagus sylvatica and V. tinus produced necrotic lesions of 2.6 ± 0.5 cm (2.1 to 3.5) and 4.7± 0.5 cm (3.8 to 5.6) respectively after 3 weeks of incubation at 23°C in the dark. Inoculation on V. tinus leaves resulted in lesions averaging 3.3 ± 1.1 × 2.1 ± 0.6 cm (range 2 to 5 × 1.5 to 3) after 2 weeks of incubation at 23°C in the dark. Control plant material showed no symptoms.The Phytophthora taxon Pgchlamydo has been reported on several ornamental and woody species, including Arctostaphylos sp., Camellia spp., Laurus nobilis, Buxus sempervirens, Rhododendron sp., Arbutus unedo, Prunus sp., Pseudotsuga sp., and Sequoia sempervirens, in North America and Europe (1,2). This is the first report, to our knowledge, of this taxon on V. tinus in Italy. V. tinus is widely sold in European nurseries, and it is also one of the most common hosts of P. ramorum (4). The fact that V. tinus is a host for both oomycetes, and the two microorganisms induce a similar symptomology (wilt), might complicate the control efforts of the phytosanitary inspection services aimed at restricting P. ramorum foci in Europe.

1 aGinetti, B.1 aCarmignani, S.1 aRagazzi, A1 aMoricca, S. uhttp://apsjournals.apsnet.org/doi/10.1094/PDIS-03-14-0282-PDN