1a. Objectives (from AD-416):
To develop and test a fruit tree rapid-cycling breeding program and to develop novel plum breeding germplasm.
1b. Approach (from AD-416):
Early flowering transgenes will be utilized to develop a rapid-cycling breeding system to dramatically shorten plum generation time. Using this approach, improved plum germplasm with Plum Pox Virus (PPV) resistance and high sugar control will be developed. "Specialty Crops Research Initiative Proposal"
3. Progress Report:
The 'FasTrack' breeding system has been used to rapidly develop the second generation of plums integrating Plum pox virus (PPV) resistance from 'HoneySweet' plum into the genetic background of California-adapted plums. A large number of 'HoneySweet' progeny were obtained. Those that have flowered have been crossed with selected California varieties. Molecular markers have been developed that distinguish the genetic background of 'HoneySweet' (PPV resistant) and 'French' (California-adapted plum variety) to aid in selecting progeny with the optimum combination of traits required by the California industry and with PPV resistance. Cultural systems to improve early flowering plum tree growth, fruit production, and seed germination have been developed. Early flowering lines planted in the field under an APHIS permit flowered in the spring (April) with standard plums and continued flowering into the early summer (June). Fruit from cross pollinations of these plums with 'HoneySweet' will be used to compare fruit growth and quality of early flowering clones in the greenhouse and field, and as additional sources of seedlings. Members of the research team met with the California Dried Plum Board and presented a project progress report. A publicly accessible 'FasTrack' breeding website was initiated with information concerning the project and its progress.