Investigation of an outbreak ofSoil-borne wheat mosaic virusin New Zealand

Abstract

Soil-borne wheat mosaic virus (SBWMV) was identified using transmission electron microscopy, enzymelinked immunosorbent assay (ELISA) with SBWMV-specific antibodies and reverse transcription-polymerase chain reaction (RT-PCR) tests with SBWMV-specific primers and sequence comparison in two out of five samples collected from a wheat (Triticum aestivum) plant showing severe leaf mosaic. The plant was also infected with Barley stripe mosaic virus and Barley yellow dwarf virus-MAV and -PAV. A further 28 out of 200 wheat samples tested positive for SBWMV using ELISA. A comparison of 11 New Zealand SBWMV isolates indicated that they were all identical and had 98% nucleotide sequence identity with SBWMV isolates from the United States, subgroup New York-Illinois. At the location of the SBWMV outbreak the vector, Polymyxa graminis, was detected by PCR and the identity was confirmed by sequencing. This is the first report of SBWMV in New Zealand.