APS Abstract of Presentation

Sequence comparisons between Hosta virus X isolates and differential infection of hosta cultivars
C. DE LA TORRE (1), D. Lewandowski (1)
(1) Department of Plant Pathology, The Ohio State University, Columbus, OH, USA
Phytopathology 98:S45

Hosta virus X (HVX) is the most economically important virus infecting hostas. HVX is mechanically transmitted and causes different symptoms including green spots, mottling, mosaic and leaf necrosis that vary according to the hosta cultivar. The use of resistant varieties and the study of HVX variability can help to minimize the spreading of this virus and the significant losses to growers. The first objective of this research was to examine sequence variability between different HVX isolates. The coat protein gene of ten Ohio HVX isolates was sequenced and compared with isolates from Minnesota (AJ517352) and Korea (AJ620114). A range of 98.9 - 100 and 99.5 - 100 percent identities at the nucleotide and amino acid level respectively, was found between all isolates. A full-length cDNA clone of Ohio isolate (H37) was constructed by overlap RT-PCR and sequenced. Comparison of the triple gene block (TGB) between H37 and AJ620114 shows 98.7, 99.7 and 98.2 nt percent identities and 96.1, 99.1 and 98.7 aa percent identities for TGB 1 (26 kDa), TGB 2 (13 kDa) and TGB 3 (8 kDa), respectively. The second objective was to screen different hosta cultivars for resistance. Twenty-four different hosta cultivars were mechanically inoculated with H37. Inoculated and non-inoculated upper leaves were assayed by DAS-ELISA at 14, 28 and 56 dpi. Twelve cultivars were systemically infected, 11 were locally infected and one cultivar was not detectably infected.

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