1a. Objectives (from AD-416):
The objective of this project is to develop, through gene transfer technologies, stone fruits with resistance to Plum pox virus and an exotic invasive pathogen, rootstocks for fruit trees that will produce dwarf trees, and/or fruit with improved eating quality. The work at EPCOT falls under our research project plan.
1b. Approach (from AD-416):
Genetic engineering will be utilized to improve traits that have been either impossible or too time consuming to approach through traditional techniques. These traits include the development of dwarfing rootstocks for Pyrus (pear) and Prunus (stone fruits), the development of Plum pox virus resistant stone fruits, the improvement of fruit quality traits including the development of stoneless stone fruits, and the production of early flowering lines for speeding the fruit breeding process. We have developed a rapid high throughput transformation system in plum and a technology for early flowering and fruiting. We will use this system to rapidly test genes of interest. Those of interest will be applied for the improvement of stone fruits, particularly plum, and also pear. The genetically engineered plants developed at EPCOT will be further evaluated at Kearneysville in the greenhouse and field (with appropriate permits). The work at EPCOT is critical to us achieving our research project plan's milestones. The ARS staff at EPCOT is competent, motivated, and experienced. The facilities are good. We feel that achieving the objectives of the five-year-plan will provide not only good scientific information but also will lead us to the development of exciting new products for the pear and stone fruit industries.
3. Progress Report:
Plums were transformed with a series of gene constructs designed and produced at the Appalachian Fruit Research Station in Kearneysville, WV, to induce Plum pox virus (PPV) resistance. Several hundred plants were regenerated at the EPCOT laboratory and transferred under an APHIS permit to AFRS, where they have been grown out. The EPCOT laboratory also produced a number of transgenic plum lines expressing the GA2 oxidase gene which produced short internode dwarf plants. Shoot and root growth of these transgenic plants are altered and studies are underway to critically evaluate growth, dry matter partitioning, gene expression, and GA levels. These have been grafted with standard plums to evaluate the potential of these genetically engineered rootstocks to dwarf the scion grafted to them. A number of plum lines transformed with the early flowering FT gene construct were produced at the EPCOT laboratory and transferred under a permit to AFRS. These are being evaluated for early flowering phenotype for inclusion in the 'FasTrack' breeding program.