Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/13/2007
Publication Date: 7/29/2007
Citation: Nagel, A.K., Nyczepir, A.P., Scorza, R., Petri, C., Schnabel, G. 2007. The Gastrodia anti-fungal protein confers increased resistance to Phytophthora root rot and the root-knot nematode in a fruit tree species. Phytopathology. 97(7):S82. Interpretive Summary: The use of transgenics to increase disease resistance in agricultural crops is becoming a viable alternative to traditional disease management methods. Much of the transgenic work and success as an alternative to disease management has been mostly conducted in field crops, such as soybean, corn and cotton, with only a few horticultural crops benefiting from this technology. In 2005-2006, we evaluated the ability of a natural disease resistance gene isolated from an Asian orchid to produce fungal disease and nematode resistance in fruit trees using plum as the model for other fruit tree species. Our results indicate that the Gastrodia antifungal protein (GAFP) gene appeared to increase disease resistance in plum to Phytophthora root rot and root-knot nematode; both pathogens known to cause root disease and stunting problems in tree fruit crops, respectively. All transgenic lines tested were susceptible to the ring nematode. Our work demonstrates that non-genetically engineered varieties could be grafted onto these genetically engineered resistant rootstocks to produce fruit trees that would survive longer and require less pesticide where Phytophthora root rot and root-knot nematode problems exist.
Technical Abstract: The Gastrodia Anti-Fungal Protein (GAFP) is a monocot mannose-binding lectin isolated from the Asiatic orchid Gastrodia elata. This protein, among others, enables the orchid to live parasitically off the basidiomycete pathogen Armillaria mellea. GAFP has been shown to confer resistance to transgenic tobacco against diseases from multiple phylogenetic lineages, including straminipila, metazoa, and fungi. The unique broad-spectrum activity of this protein makes it an interesting candidate for the production of a disease-resistant rootstock for fruit trees, but it was unknown how this lectin would behave in a tree species. Three transgenic plum (Prunus domestica var. ‘Stanley’) lines (4J, 4I, and 5D) were obtained via Agrobacterium tumefaciens-mediated transformation. After expression and translation of the GAFP-VNF isoform was verified, plum lines were challenged with common stone-fruit pathogens. We found increased resistance in line 4J to Phytophthora cinnamomi and in all transgenic lines to Meloidogyne incognita. We found increased resistance to Sclerotium rolfsii in line 4I, but results were inconsistent between replicated experiments. No effect was observed against Criconemoides xenoplax. Future work will clarify if transgenic lines will confer resistance to Armillaria root rot in the field.