The effect of white clover mosaic virus on nodulation of white clover (Trifolium repens L. cv. Ladino)

Abstract

White clover mosaic virus infection of Ladino clover seedlings resulted in decreased plant weight and a 71 % decrease in the number of nodules per plant without the decrease in nodule size which is usually observed when legumes are virus-infected. Nodule numbers decreased both on plants nodulated with an effective strain and on those with an ineffective strain of Rhizobium.

Estimating the agronomic impact of white clover mosaic virus on white clover performance in the North Island of New Zealand

“…The high incidence of WC1MV and the large effects of virus infection on dry matter production confirm earlier reports on the importance of this virus in New Zealand (Fry 1959;Latch & Procter 1966;Forster et al 1984). Our results, combined with those of other studies showing that WC1MV infection of red or white clover can also depress nodulation and nitrogen fixation (Guy et al 1980;Forster et al 1984;Khadhair & Sinha 1984), show that under current agricultural practices this virus has the potential to exert significant negative effects on productivity of New Zealand pastures. Stolon elongation (plant spread) was the specific component of white clover growth most affected by WC1MV infection in our study, with no significant effect on leaf length and petiole height.…”

“…The widespread distribution of WC1MV in our studies, combined with its effects on dry matter production and likely effects on nitrogen fixation (Guy et al 1980;Forster et al 1997), indicates the potential for using virus-resistant plants for pasture improvement. Ideally, this resistance should also include protection against alfalfa mosaic virus and clover yellow vein potyvirus which are already established in New Zealand, and other serious viral pathogens of white clover such as clover yellow mosaic potexvirus and peanut stunt cucumovirus, which have not yet become established in New Zealand.…”

“…Furthermore, the virus was shown to depress growth of white clover in the glasshouse by 24%, and to depress growth of subterranean clover and red clover by 36% and 55%, respectively (Fry 1959). In a number of other studies in New Zealand, Australia, and North America, WC1MV infection of white clover has been shown to decrease dry matter production by up to 56%, nodulation and nitrogenase activity by up to 70%, and seed yields by up to 90% (Fry 1959;Tapio 1970;Barnett & Gibson 1977;Guy et al 1980;Scott 1982;Forster et al 1984;Catherall 1987;Garrett 1991;Potter 1993).…”

Breeding Forage Plants in the Genome Era

“…Viruses such as alfalfa mosaic alfamovirus (AMV), white clover mosaic potexvirus (WCMV) and clover yellow vein potyvirus (CYVV) have been found to have significant adverse effects on forage legumes (Guy et al 1980;Garrett 1991;Johnstone and Chu 1992;Forster et al 1997;Dudas et al 1998). Bach of these viruses individually infects a large number of plant species, has a worldwide distribution, and causes significant losses, especially in pasture and grain legumes.…”

Post-transcriptional gene silencing as an efficient tool for engineering resistance to white clover mosaic virus in white clover (Trifolium repens)

“…White clover mosaic virus (WCMV), a potexvirus, occurs worldwide and is one of the most prevalent viral diseases of white clover, significantly reducing potential productivity (Barnett and Gibson, 1977;Guy et al, 1980;Garrett, 1992;McKirdy and Jones, 1997;Dudas et al, 1998). WCMV has a narrow range of (mainly leguminous) hosts, is mechanically transmitted, and produces disease symptoms ranging from sub-clinical to chlorotic mottling and systemic leaf mosaic (Hampton, 1963;Barnett and Gibson, 1977;Barnett and Diachun, 1985;McKirdy and Jones, 1997).…”