Submitted to: Phytopathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/12/2006
Publication Date: 3/1/2007
Citation: Lim, H., Ko, T., Hobbs, H.A., Lambert, K.N., Yu, J.M., Mccoppin, N.K., Korban, S.S., Hartman, G.L., Domier, L.L. 2007. Soybean mosaic virus helper component-protease alters leaf morphology, and reduces seed production in transgenic soybean plants. Phytopathology. 97:366-372. Interpretive Summary: Viruses cause diseases in plants that significantly reduce the value of cultivated crops. For example, Soybean mosaic virus (SMV) can cause significant reduction in the quantity and quality of soybean seed harvested from infected plants. The mechanisms by which viruses cause these diseases are just beginning to be understood. In this paper, we showed that expression of a single gene from SMV in transgenic soybean plants altered host responses to virus infection, produced deformations in soybean leaves, and reduced seed production all in dose-dependent manners. The expression of the Soybean mosaic virus gene also altered the expression of a set of genes that have been shown in other plants to be involved in developmental processes and stress responses, which likely is the mechanism by which Soybean mosaic virus produced the observed symptoms. The information presented in this manuscript will be of interest to researchers who are interested in understanding the etiology of virus disease in plants and limiting their impact on crop productivity.
Technical Abstract: Transgenic soybean plants expressing Soybean mosaic virus (SMV) helper component-protease (HC-Pro) had altered unifoliate leaf morphologies, responses to virus infection and reduced seed production. When inoculated with SMV, plants expressing the lowest level of HC-Pro mRNA initially showed mild symptoms similar to those of transgenic soybean plants transformed with the beta-glucuronidase (GUS) gene, while plants that accumulated the highest level of SMV HC-Pro initially showed very severe symptoms. Two weeks later, at the emergence of the seventh trifoliate leaf, symptoms disappeared and SMV titers were greatly reduced. Analyses of SMV RNA abundance over time showed that the HC-Pro region of the SMV genome was targeted for degradation before the coat protein region. This suggested that high levels of HC-Pro mRNA accumulation were required to trigger antiviral silencing responses. The accumulations of SMV-specific siRNAs were related to the levels of viral genomic RNA accumulation, and siRNA diminished as symptoms disappeared in SMV infected transgenic lines. Expression of SMV HC-Pro and SMV infection altered the accumulation of mRNA putatively targeted by miRNAs, but not the accumulation of miRNAs.