Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2009
Publication Date: 12/1/2009
Citation: Nyczepir, A.P., Nagel, A.K., Schnabel, G. 2009. Host status of three transgenic plum lines to Mesocriconema xenoplax. HortScience. 44(7):1932-1935. Interpretive Summary: In the southeastern United States, the productive life span of peach trees does not exceed 6-10 years on some sites. One cause of early tree death is a disease complex known as peach tree short life (PTSL). The ring nematode, Mesocriconema xenoplax, is associated with making peaches more susceptible to PTSL tree death. The use of genetic engineering (GE) to increase disease resistance in agricultural crops is developing into an acceptable and complementary technique to traditional disease management methods. GE has been mostly used in field crops, such as soybean, corn and cotton, but few horticultural crops (e.g., Prunus rootstocks) have benefited from this technology. Evaluating genetically transformed rootstocks for resistance/tolerance to the ring nematode is important in determining the potential use of these rootstocks as a management tool for the peach industry in the southeastern United States. Greenhouse studies were initiated to examine the susceptibility of three transgenic plum lines to Mesocriconema xenoplax. Results indicate that all three lines supported ring nematode reproduction, but line 5D suppressed nematode populations more than lines 4I and 4J. These data provide useful insights into the potential utilization of a genetically transformed plum rootstock to manage ring nematode in peach in the southeastern United States.
Technical Abstract: Gastrodianin anti-fungal protein (GAFP) increases tolerance against Phytophthora root rot and root knot nematode (Meloidogyne incognita) in transgenic plum lines. However, nothing is known about the potential of GAFP lectin to confer resistance to the ring nematode Mesocriconema xenoplax. Three transgenic plum lines (i.e., 4I, 4J, and 5D) expressing gafp-1 under the control of CaMV35S promoter sequence were evaluated for their susceptibility to Mesocriconema xenoplax in the greenhouse. All plum lines were rated as hosts of M. xenoplax. Among the individual plum lines tested, the number of M. xenoplax per gram of dry root was lowest for transgenic line 5D, intermediate with the control, and greatest with line 4J. It was determined that reproduction as measured by number of M. xenoplax per gram of dry root was a better measure of host resistance than number of M. xenoplax/100 cm3 soil.