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Fusarium root rot is a major pea disease in Canada and only partial tolerance exists in germplasm. Transgenic technologies may hold promise but the economic benefits of genetically modified (GM) pea will need to surpass the regulatory costs, time and labor involved in bringing a GM crop to market. European pea (Pisum sativum L.) cultivars expressing four antifungal genes, 1-3 β glucanase (G), endochitinase (C) (belonging to PR proteins family), polygalacturonase inhibiting proteins (PGIPs) (P) and stilbene synthase (V) have been transformed for disease tolerance and showed disease tolerance under laboratory conditions. Transgenic lines with four antifungal genes inserted either individually or stacked through crossing were tested for their efficacy against Fusarium root rot (Fusarium avenaceum) in confined trials over three years (2013 to 2015) in comparison with two parental German lines and three Canadian lines. Superior emergence, higher fresh weight or lower disease ratings above and below ground, of transgenic lines in presence of disease inoculum were not observed consistently in the three years of field experiments when compared to the parental and Canadian lines in the presence of disease inoculum. No indication of an advantage of stacked genes over single genes was observed. Most transgenic lines had lower relative gene expression in the roots than in the leaves in greenhouse trials suggesting a possible explanation for poor tolerance to Fusarium root rot. Field trials are necessary to verify the agronomic performance and ecological relevance of the promising effects detected under laboratory conditions.

Genetically modified crops have raised concerns about unintended consequences on non-target organisms including beneficial soil associates. Pea transformed with four antifungal genes 1-3 β glucanase, endochitinase, polygalacturonase-inhibiting proteins, and stilbene synthase is currently under field-testing for efficacy against fungal diseases in Canada. Transgenes had lower expression in the roots than leaves in greenhouse experiment. To determine the impact of disease-tolerant pea or gene products on colonization by non-target arbuscular mycorrhizae and nodulation by rhizobium, a field trial was established. Transgene insertion, as single gene or stacked genes, did not alter root colonization by arbuscular mycorrhiza fungus (AMF) or root nodulation by rhizobium inoculation in the field. We found no effect of transgenes on the plant growth and performance although, having a dual inoculant with both AMF and rhizobium yielded higher fresh weight shoot-to-root ratio in all the lines tested. This initial risk assessment of transgenic peas expressing antifungal genes showed no deleterious effect on non-target organisms.