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United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION AND UTILIZATION OF THE GENETIC RESOURCES OF APPLES, GRAPES, AND TART CHERRIES
2010 Annual Report


1a.Objectives (from AD-416)
1. Strategically expand the genetic diversity in genebank collections and the quality and quantity of associated information for priority cold hardy grape, tart cherry, and apples and their wild relatives.

2. Conserve and regenerate priority cold hardy grape, tart cherry, and apple genetic resources efficiently and effectively, and distribute samples and associated information worldwide.

3. Strategically characterize ("genotype") and evaluate ("phenotype") priority cold hardy grape, tart cherry, and apple genetic resources for molecular markers and highly heritable horticultural and morphological traits.


1b.Approach (from AD-416)
The objectives of this project will be met by: a) Surveying existing domestic and international collections of Vitis, Malus, and Prunus (tetraploid cherry) to identify material that would refine and fill gaps in NPGS collections; b) acquiring new accessions of wild species and heirloom cultivars, and as appropriate, genetic stocks of apple, cold-hardy grape, and tart cherry that have been extensively characterized genetically; c) enlisting genetic marker and other information to refine the holdings of the preceding priority genera by de-accessioning materials that are misidentified or unnecessarily redundant; d) conserving, regenerating, and distributing cold hardy grape, tart cherry, and apple genetic resources and associated information; e) backing up primary collections of cold hardy grape, tart cherry, and apples via nursery plantings, cryopreservation, and seed samples; f) developing and applying genetic markers for phylogenetic and genetic diversity analyses, emphasizing SSRs and sequence-based markers in cold hardy grape, tart cherry, and apples; g) generating SSR fingerprints for all priority accessions (ca. 5,000) of cold hardy grape, tart cherry, and apples and use them to determine the identity, diversity, phylogeny, and systematics of these genetic resources, and to enhance the effectiveness of genetic resource management; and h) incorporate characterization data into GRIN and other databases, and evaluating in collaborative research program, highly heritable traits of cold hardy grape, tart cherry, and apples according to CGC-approved descriptors, and incorporate data into GRIN and other databases. The primary link with users will be through Crop Germplasm Committees that define crop priorities for collection and evaluation.


3.Progress Report
Maintenance and delivery of germplasm to clients and stakeholders is the primary objective in this project. Approximately 9,000 accessions of apple, grape and tart cherry were maintained in the field repositories and some of them were further safeguarded in cryopreservation storage. Characterization of the germplasm collections is another important objective in this project. In collaboration with others, we evaluated the chromosome number (ploidy) of apple accessions and found that most apple species are diploid (2x), but some have 3x or more. We continued a project to screen resistance to the apple scab disease in our apple collections. Of the 399 seedlings derived from the 6 core collections, 41% are resistant to apple scab. Of the 456 seedlings in the 9 core collections, 38% are resistant to apple scab. We also performed evaluations for fruit quality involving 70 ancestors and founders of modern apple breeding germplasm to support the NRI-NIFA project “Functional gene markers for tree fruit texture”. For the project, we provided samples to Wenatchee, WA, for fruit quality evaluation (crispness, firmness, juiciness, sweetness, acidity, size) and 90 seedlings from three populations of ‘Gala’ x Malus sieversii that represent the first deliberate efforts to introgress the desirable attributes of the ancestor of domestic apple (M. sieversii) into modern cultivars. We furthered the understanding of identity and diversity of apple accessions in the collection through characterization with molecular markers. We collected and used chloroplast DNA sequence data, along with phenotypic data, to confirm species assignments of Chinese and other apple species. SSR fingerprints for 1274 Malus domestica (common apple) were completed and loaded into GRIN last year. We continued the work of searching for novel disease resistance genes in 40 apple accessions and found that some of these genes were associated with known QTLs for resistance to the major apple diseases such as fire blight, apple scab and powdery mildew. These markers were added to both apple rootstock and scion maps. We continued our effort in grape germplasm characterization. A genetic map has been constructed of the Horizon x Illinois 547-1 mapping population and used to identify a single, major QTL controlling several leaf morphology traits and predatory phytoseiid mite abundance on linkage group 1. We also validated 955 grape SSR fingerprints at eight loci by fingerprinting the second vine per accession. In addition, we took approximately 3,000 bud break observations and many images of key horticultural traits in the grape collections. In a collaborative project, we characterized 36 polyphenols for 340 V. vinifera accessions from the USDA-ARS Clonal Repository at Davis, California and 200 wild accessions of mainly native species from the Geneva repository. Data analysis is in progress. These secondary metabolites are important to human nutrition and health. We also supported a project for screening resistance in our grape germplasm collections to powdery mildew and downy mildew diseases. The entire grape collections (approximately 1,400 accessions) were screened.


4.Accomplishments
1. Provision of unique genetic sources of apple, grape & tart cherries to fruit breeders and researchers for crop improvement. ARS Researchers in Geneva, NY distributed 184 orders for 3466 apple and tart cherry accessions and 74 orders for 2102 grape accessions. These distributions will contribute to the new breakthroughs of fruit research in both US and the rest of the world.

2. Use of cryogenic storage for conservation of apple genetic resources. To provide additional safeguard for apple germplasm, ARS Researchers in Geneva, NY have 2,807 accessions of the collections backed up at NCGRP through cryogenic preservation of dormant buds. Presently 2,275 of 2,621 apple cultivars/clones in the main collection are backed up. Through this effort, the apple and tart cherry germplasm are well secured for future needs of varietal improvement.

3. Replication of the Apple Core Collection in the Pacific Northwest. To meet the breeding needs of the U.S.’s largest apple production region in the Columbia River Valley of WA, ARS Researchers in Geneva, NY planted a replicate of 227 apple accessions of the core collection in March 2010 at Washington State University’s Sunrise Research Orchard. In addition, a replication of key ‘Gala’ x M. sieversii genetic mapping population (GMAL 4593) was planted in May 2009 at the Orchard as part of WSU’s Apple Germplasm Library. Availability of these core apple collections to the WSU’s apple breeding programs will accelerate the pace of varietal improvement in the region. Article on this effort appeared in the industry trade journal Good Fruit Grower, July 2009 (www.goodfruit.com/Good-Fruit-Grower/July-2009/In-search-of-superior-apples/).


Review Publications
Volk, G.M., Richards, C.M., Forsline, P.L. 2010. A comprehensive approach toward conserving Malus germplasm. Acta Horticulturae. 859:177-182.

Volk, G.M., Richards, C.M., Henk, A.D., Reilley, A.A., Reeves, P.A., Forsline, P.L., Aldwinckle, H.S. 2009. Capturing The Diversity Of Wild Malus Orientalis From Georgia, Armenia, Russia And Turkey. Journal of the American Society for Horticultural Science. 134:453-459.

Last Modified: 10/25/2014
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