Efficacy of Transgenic Disease Resistant Peas Against Fusarium Root Rot (Fusarium spp.) in Field.

In field pea, Fusarium root rot complex is a major production-limiting factor. Conventional breeding techniques have had limited success at producing resistant varieties but approaches using genetic modification may hold promise. European pea cultivars were previously transformed with genes encoding for four pathogenesis-related proteins: 1, 3-β glucanase; polygalacturonase inhibiting proteins (PGIPs); anti-microbial small molecules (stilbene synthase) and endochitinase. In summer 2013, 14 lines transformed with single or stacked genes, parental and elite Canadian lines were inoculated with Fusarium avenaceum in field trials. Transgenic lines challenged with Fusarium exhibited greater seedling survival (%), total fresh weight (g/plot) and lower root rot disease ratings. Differences between promoters, single and stacked genes and transformation events were observed. Some lines containing a single transgene were effective, but stacked genes were not necessarily more effective than single insertions. Transgenic lines were also inoculated with beneficial arbuscular mycorrhiza (Glomus intraradices) fungi and common pea inoculant (Rhizobium leguminosarum), in a separate field trial and colonization of roots by arbuscular mycorrhiza fungus and rood nodulation were quantified. No evidence was found to suggest that pathogenesis related proteins inhibited beneficial association by arbuscular mycorrhiza fungus or nodulation. Evaluation of efficacy of transgenic lines under field conditions will allow the potential benefits of disease resistance to be weighed against regulatory costs.