Submitted to: HortScience
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/10/2011
Publication Date: 7/15/2011
Citation: Kalariya, H.M., Schnabel, G., Petri, C., Scorza, R. 2011. Generation and characterization of transgenic plum lines expressing gafp-1 with the bul409 promoter. HortScience. 46:975-980. Interpretive Summary: The use of genetic engineering (GE) to increase disease resistance in agricultural crops is becoming a viable complementary technique to traditional disease management methods. The total area devoted to growing GE crops has seen a significant increase in the past decade. This increase has been mostly in field crops such as soybean, corn and cotton, but few horticultural crops have benefited from this technology. We have evaluated the ability of a natural disease resistance gene isolated from an Asian orchid to produce disease and nematode (microscopic worms that feed on tree roots) resistance in fruit trees using plum as the model for other fruit tree species. We have shown that this gene, the Gastrodia anti-fungal protein (GAFP) gene, increased resistance in plum to a disease produced by a fungus (Phytopthora) and to a nematode that causes serious root damage to fruit crops. Our work shows that the GAFP gene has the potential for developing fruit tree rootstocks that are root disease and nematode resistant. Non-genetically engineered varieties could be grafted onto these genetically engineered resistant rootstocks to produce trees that would survive longer and require less pesticide use for the production of fruit.
Technical Abstract: The Gastrodia anti fungal protein (GAFP-1) is a mannose-binding lectin that can confer increased disease resistance in transgenic tobacco and plum. In all previously-generated transgenic lines, the gene was under the control of the 35SCaMV promoter. In this study, transgenic plum lines were created from seeds derived from open pollination of the cultivar, Bluebyrd (BB-OP), with gafp-1under the control of the polyubiquitin promoter, bul409, and evaluated for Phytophthora root rot (PRR) and Root knot nematode (RKN), susceptibility. One of nine transgenic lines synthesizing GAFP-1 exhibited increased tolerance to PRR caused by P. cinnamomi. The same line (BB-OP-1) was also significantly more tolerant to RKN infection caused by Meloidogyne incognita. BB-OP-1 was more resistant to PRR and equally resistant to RKN compared to the cultivar, Stanley-derived 4J line, which expresses gafp-1 under the control of the 35SCaMV promoter. GAFP-1 synthesis in BB-OP-1 was not elevated by pathogen infection, suggesting that the bul409 promoter is not inducible in the plum/GAFP-1 system. This study confirms the usefulness of the gafp-1 gene in various cultivars of transgenic plum and establishes that the bul409 promoter is at least equal in effectiveness to the 35SCaMV promoter for gafp-1 expression in transgenic lines of woody plants.