Seasonal Progression, Symptom Development, and Yield Effects of Alfalfa mosaic virus Epidemics on Soybean in Wisconsin

Abstract

The occurrence of Alfalfa mosaic virus (AMV) has increased in Wisconsin soybean fields in conjunction with the establishment of the soybean aphid (Aphis glycines). Field studies were conducted to determine the seasonal incidence of AMV-infected plants, progression of symptom severity caused by AMV, and the effect of AMV on soybean yield and seed quality. An isolate of AMV, collected from field-grown soybean, was introduced into plots by mechanical inoculation of plants at the V1 growth stage. The goal of the experiment was to achieve an incidence of AMV-infected plants of 0, 50, and 100% in 2002, and 0, 10, 25, 50, 75, and 100% in 2003. Severity of foliar symptoms was rated, and leaf samples were collected for serological assay (enzyme-linked immunosorbent assay [ELISA]) to estimate the incidence of AMV-infected plants from growth stages VC to R5. The maximum incidence of AMV-infected plants was 49% at growth stage R5, yet detection of the virus by ELISA dropped dramatically thereafter in both years. Incidence of AMV-infected plants accounted for 53 to 67% of the variability observed for severity of foliar symptoms in 2002 and 2003, respectively. Maximum yield loss ranged from 32% in 2002 to 48% in 2003 based on the difference in yield between noninoculated plots and plots with the highest incidence of AMV-infected plants. Incidence of AMV-infected plants explained 31% of the variation in yield in 2002 and 26% in 2003. An AMV incidence of 30% or greater was required for yield loss caused by AMV. Results of this study suggest that AMV has the potential to lower soybean yield and warrants further study.

Diagnostic Potential of Polyclonal Antibodies Against Bacterially Expressed Recombinant Coat Protein of Alfalfa mosaic virus

“…AMV is an emerging viral problem of soybean {Gly-cine max (L.) Merrill) in the United States, particulariy in fields located in the Midwest (6,9,19,27). In Wisconsin, AMV was found associated with yield reductions of 31 and 26% in 2002 and 2003, respectively (27).…”

Seasonal Phenology of Aphis glycines (Hemiptera: Aphididae) and Other Aphid Species in Cultivated Bean and Noncrop Habitats in Wisconsin

“…Commercial bean production, including soybean, Glycine max (L.) Merr., and snap bean, Phaseolus vulgaris L., has been particularly impacted. In snap bean, common symptoms of virus infection are stunted growth, ßoral abscission, and pod distortion, which ultimately result in reduced quality and severe yield losses for producers (Burrows et al 2005, Mueller and Grau 2007, Larsen et al 2008. Recent surveys of commercial snap bean Þelds revealed high incidence of Alfalfa mosaic virus (family Bromoviridae, genus Alfamovirus, AMV), Bean yellow mosaic virus, Clover yellow vein virus, Cucumber mosaic virus (family Bromoviridae; genus Cucumovirus, CMV), and Tobacco streak virus, all of which are transmitted by aphids in a nonpersistent manner , Larsen et al 2002, Shah et al 2006.…”

Co-infection of Soybean withSoybean mosaic virusandAlfalfa mosaic virusResults in Disease Synergism and Alteration in Accumulation Level of Both Viruses

“…In soybean, SMV (genus Potyvirus; family Potyviridae) is considered widespread, and seven strains of the virus, identified based on differential interactions with selected soybean genotypes, have been reported from the United States (4). On the other hand, AMV (genus Alfamavirus; family Bromoviridae) is an emerging viral problem of soybean in the midwestern United States (20). In Wisconsin, AMV has been a factor in yield reduction by 31 and 26% in 2002 and 2003, respectively (20).…”

“…Unlike SMV, AMV is biologically a highly variable virus (9). The recent increase in incidence of AMV in the midwestern United States is partly attributed to the introduction of the soybean-colonizing aphid (Aphis glycines) (20), which is capable of transmitting AMV as well as SMV among other viruses (6,14,30).…”