Performing Department
Agricultural & Environmental Sciences
Non Technical Summary
No peach cultivar resistant to major diseases currently occupies any substantial U.S. market share. The perfect peach, - consistently exceeding consumer expectations with satisfying appearance, aroma, flavor, shelf life, and texture and meeting industry needs for durable disease resistances - remains elusive. Desired fruit quality combined with disease resistance and production traits are lacking in current peach germplasm, therefore required genes often must be transferred from related wild or exotic germplasm. Improved molecular and biochemical markers for resistance and horticultural traits need to be simultaneously developed to allow efficient gene transfer to commercially acceptable varietal types. Improved varieties conferring high market fruit quality and able to withstand harvest and post-harvest handling are essential for continued economic viability of the South Carolina peach industry and supporting crop-producing rural communities. The next generation of peach cultivars with superior horticultural quality that are also disease resistant will reduce the environmental costs and human health risks associated with pesticide load in the agro-ecosystem. Consumers will benefit from greater access to a more stable supply of nutritious fruit with superior eating qualities that will translate into increased per capita consumption and improved human health and well-being.For generations, peaches have been a valuable asset to South Carolina agriculture. With approximately 18,000 acres of peaches, South Carolina ranks second nationally, behind California, in fresh peach production and interstate shipments. Approximately 30 to 40 varieties of peaches grown in South Carolina yield over 200 million pounds of fresh market peaches, with production value at $35 million. In the last few years, the value has dropped to between $20 to $30 million because of droughts and other weather conditions. Continued viability of the South Carolina peach industry is crucial to the economic survival of these mostly family farms, as well as the associated rural communities built around these farming and processing enterprises. Peach growers and processors are facing increasing threats from diseases and pests, combined with increasing market demands for quality and variety in a time where pesticides, fungicides and other agrochemicals are being lost and good agricultural land is becoming rare. This project is developing improved varieties of fresh market peach, which incorporate genetic solutions to production problems, such as diseases, while enhancing fruit quality. Traditional breeding approach in combination with marker-assisted parental and seedling selection provides efficient way of incorporating desired characters into newly developed peach varieties that address industry needs and consumer demands.
Animal Health Component
40%
Research Effort Categories
Basic
30%
Applied
40%
Developmental
30%
Goals / Objectives
Increase breeding efficiency for bacterial spot and/or brown rot tolerant/resistant high quality peach varieties suitable for the southeastern USA by discovering markers associated with leaf resistance to bacterial spot, and brown rot resistance in green and ripe peach fruit and enabling marker assisted breeding. Combine disease resistance alleles for both diseases with excellent fruit quality in superior peach cultivars. This goal will be achieved thorugh the follwoing objectives:Peach germplasm evaluation with available molecular markers linked to the genes of interest to facilitate the breeding program in combining the best traits isolated in different varieties or in other species from the Prunus genus.Discovery of new/additional markers linked to genes associated with fruit quality and disease resistance.Development of high quality, disease resistant peach varieties adapted to environmental conditions of South East USA.
Project Methods
Functional alleles discovered in RosBREED will be used to search genotypic data obtained by genotyping by sequencing of peach germplasm available at Clemson University and Prunus NCGR collection at Davis, CA, for new sources of genes associated with traits of interest. New genes will be validated for the trait phenotypic effects and new sources of important traits will be incorporated in the breeding program by acquiring pollen and/or parental trees.Disease evaluation of potential parents for crossing or progeny developed will be conducted at the field and in the lab according to the accepted procedures for the disease in question. Brown rot resistance/susceptibility will be evaluated on fruit epidermis and mesocarp tissue following the procedure established by Dr. Schnabel at Clemson University. A lab based method for detached leaf evaluation of peach bacterial spot resistance/susceptibility will be used according to the procedure established by Dr. Guido Schnabel using a previously published protocol by Randhawa et al (1985).Breeding activities will be conducted at the Clemson University Musser fruit research farm. Maternal trees will be selected from germplasm available at Musser farm, and efforts will be made to add missing varieties necessary for achieving breeding goals, to the germplasm collection. Pollen will be collected from peach germplasm collections and will be received from other breeding programs in the US and abroad to facilitate incorporation of desirable traits into the breeding program. Markers will eb used to facilitate selection of hybrids and their advancement into the next level of selection.Results will be evaluated on a yearly basis and methods adjusted accordingly, especially in disease incidence evaluation. New markers as they become available will be added to the panel for genotyping the breeding material. SC growers and county agents will be informed about our results and preliminary conclusions may assist in designing novel resistance management strategies. To discover and validate new resistance and fruit quality alleles by 2017, phenotyping of the peach populations and germplasm has to be accomplished by 2016. To phenotype for bacterial spot leaf resistance using detached leaf assay by 2017, the detached leaf assay has to be established as a routine procedure by 2016. Development of peach breeding material with pyramided and combined disease resistance alleles by 2018 is dependent on producing breeding material with pyramided alleles for individual diseases by 2016, genotyping of the newly created material by 2017, and where possible producing breeding material with disease resistance alleles for combined diseases. Pyramiding fruit quality alleles in improved breeding material by 2018 is dependent on discovery and validation of horticultural quality alleles and their validation in peach germplasm by 2017. Implementation of parental and seedling marker-assisted selection (MAPS and MASS) in years 2016-2018 and beyond is based on development of new DNA tests by 2016 and onwards