Arch Virol (1999) 144: 2059–2064
Distribution and diversity of New Zealand isolates
of ryegrass mosaic virus
D. E. Webster
, D. L. Beck
, and R. L. S. Forster
Botany Department, University of Otago, Dunedin, New Zealand
Hort Research, Mt Albert Research Centre, Auckland, New Zealand
Accepted April 21, 1999
Summary. Sequences from the coat protein cistron of ﬁve ryegrass mosaic virus
(RgMV) isolates indicated the presence of two distinct strains in New Zealand.
The nucleotide differences between the strains, and their distribution, suggested
that both strains were introduced recently, either as a mixed infection or as two
independent introductions. The relationship between these New Zealand strains
and other strains and isolates of RgMV, and their potential severity is discussed.
Ryegrass mosaic virus (RgMV) is a single stranded RNA virus that belongs to
the Potyviridae family of plant viruses. It is transmitted by the eriophyid mite
Abacarus hystrix and by mechanical sap inoculation [4, 11]. Symptoms vary
depending on the strain of RgMV and ryegrass cultivar . Yield losses of up to
27% have been reported in Italian ryegrass and up to 50% in perennial ryegrass [3,
18]. In addition, the quality of ryegrass may be signiﬁcantly reduced . RgMV
now has a worldwide distribution and is considered to be one of the most serious
ryegrass diseases in England and Australia [1, 3].
The ﬁrst report of RgMV and A. hystrix in New Zealand was in the early
1990’s . An extensive survey of pasture grasses in the mid 1970’s did not detect
RgMV in New Zealand and surveys of pasture arthropods have not previously
detected the mite vector, Abacarus hystrix [9,10]. Since its discovery RgMV
has been found in perennial ryegrass pastures throughout New Zealand .
GenBank accession numbers: RgMV-Otago strain AF091243, RgMV-Kaikohe isolate
Current address: CSIRO Plant Industry, Glen Osmond SA5064, Australia.