FIRST REPORT OF IMPATIENS NECROTIC SPOT VIRUS INFECTING ISOTOMA AXILLARIS LIDT.

Isotoma axillaris Lidt. (sin. Laurentia axillaris; also known as blue stars or rock isotome) is a perennial species of Campanulaceae native to Australia, typically cultivated as annual in Liguria region. Leaves are ovate or obvate in outline, with pinnatified lamina; solitary flowers bloom in April-May at the leaf axils. In 2011, severe symptoms resembling those caused by tospoviruses occurred in an ornamental farm located at Albenga area (Savona). Small necrotic concentric rings and necrosis of leaf lamina were present in almost 7% of plot blooming plants grown outdoors. Twenty symptomatic plants collected during inspections were maintained in insect-proof greenhouse at Bologna University. Virus was isolated by mechanical transmission to Chenopodiaceae species. Symptomatic I. axillaris was negative for Tomato spotted wilt virus and positive for Impatiens necrotic spot virus (INSV) in DAS-ELISA tests. To further confirm the presence of INSV, total RNA was extracted and used for RT-PCR. Nucleotide sequences obtained were found to be closely related to published sequences (98% nucleotide identity with INSV available under GenBank Accession Nos DQ523598, L20886, AB109100, and L20885). To now, INSV has been found in 1991 naturally infecting I. fluviatilis (sin. L. fluviatilis), another species of Isotoma, weed in Canada. Our finding is thought to be the first report of natural occurrence of INSV in I. axillaris. Investigations of the ornamental farm looking for thrips vector of INSV were performed and many populations were found, suggesting that thrips are the main responsible for INSV spreading as well as increasing of its natural hosts. FIRST REPORT OF HOSTA VIRUS X (HVX) INFECTING HOSTA IN ITALY Bellardi M.G.1, Cavicchi L.2 and Davino S.3 1 DiSTA-Patologia Vegetale, Alma Mater Studiorum, Università di Bologna, Viale G. Fanin 42, 40127 Bologna, Italy. 2 Plesso Didattico G. Scarabelli, Alma Mater Studiorum, Università di Bologna, Viale G. Ascari 17, 40026 Imola, Bologna, Italy. 3 SENFIMIZO, Sez. di Patologia Vegetale e Microbiologia agraria, Università degli Studi di Palermo, Viale delle Scienze edificio 5, 90128 Palermo, Italy. E-mail: mariagrazia.bellardi@unibo.it Species of Hosta (Liliaceae) are herbaceous perennials more often grown for their foliage (blue, gold, green or variegated) then for their flowers. Virus diseases reported elsewhere in the word on cultivated hosta species include Hosta virus X (HVX), first described in USA in 1996, and considered to be the main pathogen of this genus. In October of 2010, the following systemic virus-like symptoms were observed on leaves of three varieties cultivated in Emilia-Romagna region (Italy) (“Gold Standard”, “Sum and Substance” and “Whirlwind”): irregular green blotched scattered in the yellow lamina, green bands running along the veins having an “ink-bleeding” look, malformations, different leaf thickness. Electron microscopic observations revealed the presence of virus particles ca. 560-600 nm in length, which in ISEM and PAS-ELISA tests clearly reacted with the antiserum to HVX (provided by University of Minnesota, MN, USA). Mechanical inoculations carried out using symptomatic hosta leaf sap made it possible to transmit HVX to Chenopodium murale L. (necrotic pin-point lesions) and Gomphrena globosa L. (necrotic red spots 2-3 mm in size). By applying RT-PCR with specific primers HVXCP+ 5’-ATGGCAAGTGACGCACCAACTCCACC-3’ and HVXCP- 5’- TCAACTTGAGCCTTCCGGG-3’ that amplified a fragment of 663 nt based on the coat protein gene, HVX appeared closely related to polish isolate FJ821705 (98% nucleotide identity). To prevent HVX spread it is important to minimize mechanic contact between plantlets during cultivation, and immediately remove those showing visible virus-like symptoms. Considering that two of the infected varieties tested have been imported from Holland, certified virus-free propagation material must...