White clover (Trifolium repens) and associated viruses in the subalpine region of south-eastern Australia: implications for GMO risk assessment

Over the past several years, increased emphasis has been placed on conducting comprehensive ecological-risk assessments of virus-resistant genetically modified organisms (GMOs) prior to their release into the environment. In this paper we report on the first stage in our assessment of the level of risk posed by virus-resistant transgenic Trifolium repens L. (white clover) to native plant communities in south-eastern Australia. We investigated the distribution, abundance and phytosociological characteristics of naturalised T. repens populations in two areas in the subalpine region of New South Wales (NSW) and the Australian Capital Territory (ACT), and determined the distribution and abundance of Alfalfa mosaic virus, Clover yellow vein virus and White clover mosaic virus in 31 populations of white clover in this region. We found that T. repens is a significant component of Poa grasslands and Eucalyptus-Poa woodlands in the subalpine region, but is absent or rare in Eucalyptus species forests and Carex-Poa species bogs. Clover yellow vein virus was by far the most common virus in the study area, being present in 18% of T. repens plants across a wide range of plant communities. Alfalfa mosaic virus and White clover mosaic virus were each recorded in only one white-clover population growing in a native plant community. We conclude that white clover is a significant constituent of subalpine grasslands and woodlands in the region studied, and that of the viruses investigated, Clover yellow vein virus is the most abundant and widespread.