Submitted to: Planta
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/2006
Publication Date: 7/12/2006
Citation: Cox, K., Layne, D., Scorza, R., Schnabel, G. 2006. Gastrodia anti-fungal protein (GAFP) from the orchid gastrodia elata confers resistance to multiple root disease pathogens in transgenic tobacco. Planta. 224:1373-1383. Interpretive Summary: Crop plants are subject to attack by a large number of plant pathogens, many of which are unrelated to each other. Protection against these diverse diseases requires various chemicals or biological control agents that are specific to each disease organism. A natural disease resistance gene isolated from an orchid was used to genetically engineer plants. For this work, tobacco plants were used as a model system to test the gene, because tobacco plants are easily genetically engineered. The gene, when inserted into tobacco, significantly reduced the effects of two out of three major diseases of tobacco that were tested. It also significantly reduced damage to roots caused by nematodes, which are small parasitic worms that infect plants. The wide range of protection provided by this naturally, occurring plant gene makes this gene a good candidate for protecting crop plants against multiple diseases and pests, and may allow for the reduction in pesticide use and increases in crop productivity.
Technical Abstract: Diseases of agricultural crops are caused by pathogens from several higher-order phylogenetic lineages, including Fungi, Straminipila, Eubacteria, and Eetazoa. The lack of broad-spectrum host resistance poses difficulties in managing plant disease without the use of numerous pesticides. Due to its documented activity in vitro and structural similarity to insecticidal lectins, Gastrodia Anti-Fungal Protein (GAFP; gastrodianin) may be able to confer disease resistance to pathogens across several higher-order lineages. We transformed tobacco (Nicotiana tabacum cv. Wisconsin 38) with GAFP-1 and challenged transformants with agriculturally important plant pathogens from several higher-order lineages, including Rhizoctonia solani (fungus), Phytophthora nicotianae (straminipile), Ralstonia solanacearum (eubacterium), and Meloidogyne incognita (metazoan). Quantitative real-time PCR and western blotting analysis indicated that GAFP-1 was transcribed and translated in transgenic lines. When challenged by R. solani and P. nicotianae, GAFP-1-expressing lines had reduced symptom development and improved plant vigor compared to non-transformed and empty vector control lines. These lines also exhibited reduced root galling when challenged by M. incognita. Against Ralstonia solanacearum expression of GAFP-1, neither conferred resistance, nor exacerbated disease development. These results indicate that heterologous expression of GAFP-1 can confer enhanced resistance to a diverse set of plant pathogens and may be a good candidate gene for the development of transgenic, root-disease-resistant crops.