Dr. Aiming Wang, Agriculture and Agri-Food Canada

Soybean viral diseases are a common all over the world. In the past several years incidences of soybean viral diseases has remarkably increased in the US, Canada and many other soybean producing countries. As viral diseases have a significant impact on yield, quality and marketability of soybeans, it is a serious issue that warrants appropriate research.

Five viral pathogens that commonly cause viral diseases in soybean have been monitored in Ontario. A total of 559 soybean leaf samples were collected from commercial and experimental fields in the Harrow, London, Woodstock and Guelph areas over the past three years. Through laboratory analysis, we have discovered that four out of five of these viral pathogens are endemic in Ontario. They are:


1. Soybean mosaic virus (SMV)
2. Alfalfa mosaic virus (AMV)
3. Bean pod mottle mosaic virus (BPMV)
4 Tobacco ringspot virus (TRSV)

Of them, SMV is the major viral pathogen in Ontario with approximately 15 percent, followed by AMV (approximately six percent), TRSV (approximately three percent) and BPMV (approximately 2 percent). The data suggests that soybean viral diseases are indeed a serious problem in Ontario and SMV is a major threat.

A number of SMV isolates in Ontario were collected from the field and subjected to molecular characterization. It was found that Ontario SMV isolates belong to the G2 strain group in the US. One of these isolates is a naturally occurring resistance-breaking isolate that can infect soybean cultivars carrying a resistance gene. To understand why this isolate can overcome resistance, the genetic sequence of this isolate and its parental isolate was completely sequenced.

To screen for genetic resistance to SMV in Ontario, 52 cultivars and accession lines provided by six soybean research groups in Ontario and Iowa were tested. Eight of them showed high resistance to SMV.

To understand SMV-soybean interactions for the development of novel strategies against SMV, the replication mechanism of SMV has also been investigated. The results obtained from this project will contribute to the development of soybean varieties resistant to SMV, provide general information of SMV in Ontario, and help soybean growers select varieties which are resistant or less prone to SMV infection in Ontario.