1a. Objectives (from AD-416):
The project addresses the Specialty Crop Research Initiative (SCRI) stated need for "Developing innovative breeding systems that improve the speed and flexibility to deliver unique cultivars to meet future challenges". The proposed "FasTrack" will be an advanced fruit tree breeding system that uses transgenic early and continually flowering trees to overcome the limitations of juvenility and dormancy, producing the first generation in one year versus the normal three to seven years. Unlike conventional breeding, "FasTrack" crosses will be done in the greenhouse, and only the non-transgenic individuals from segregating populations will be released to the field. We propose to implement "FasTrack" using a transdisciplinary, whole systems approach to address the short- and long-term challenges facing the $200 million dollar California dried plum industry. Two industry specified traits, Plum Pox Virus (PPV) resistance and high sugar content, will be rapidly incorporated into industry standard germplasm. Molecular markers will be used to further improve the efficiency of the "FasTrack" rapid backcross breeding scheme. The economics of "FasTrack" breeding versus conventional breeding will be compared in two participating plum breeding programs. The project progress will be monitored by an advisory board and will be directly communicated to Prunus breeders, industry representatives, and scientists. Through consultation with domestic and foreign regulatory agencies, a comprehensive plan will be developed to determine if "FasTrack" progeny are exempt from regulation and accepted as standard varieties. Environmental and consumer-oriented NGOs will be consulted to address the public acceptance of "FasTrack" technology and pave the way for future commercial releases.
1b. Approach (from AD-416):
The "FasTrack" breeding project proposes to deliver an advanced biotechnology to an existing industry supported plum cultivar development program. "FasTrack" breeding technology will be developed to specifically meet the needs of the California dried plum industry by integrating the system with the major California dried plum industry's breeding program and targeting traits highly desired as test cases. The probability of success of this project is highly based on the long-term expertise and experience of the project investigators in plum breeding and transgenic technology of plum. This will ensure that the benefits of "FasTrack" technology are realized and lead to long-term commitments by the California dried plum industry, while at the same time, strengthening the plum "FasTrack" system’s role as a model for other tree fruit industries to follow.
3. Progress Report:
'FasTrack' breeding is a system to create a generation every year. To rapidly integrate traits into commercial germplasm for the dried plum industry, two types of parental lines were generated that have the early and continual flowering trait. The first set of lines contain the genes responsible for resistance to PPV that comes from the resistant 'HoneySweet' plum, and the second are lines that come from high quality California germplasm. These parental lines have been additionally crossed to high quality California germplasm to generate third generation early flowering lines with at least half of their genes from the high quality California adapted germplasm. To begin to mark which genes come from the California background and which genes come from the original early and continual flowering background, over 30 markers that spanned all the chromosomes generated from last years' whole genome sequences of 'Improved French' (CA background) and 'HoneySweet' (specific to the early flowering and PPV resistant background) were tested on over 30 plum cultivars as well as the early flowering plum lines to determine relatedness. As predicted, the cultivars could be grouped by how close their pedigrees related to the California germplasm. To improve the cultivation of early and continually flowering plums in the greenhouse, fertilization trials were undertaken to optimize the flowering and fruiting capabilities. A standard operating procedure was developed from this data as well as previous cultural experiments.