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United States Department of Agriculture

Agricultural Research Service

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Location: Plant Genetic Resources Research

2012 Annual Report

1a. Objectives (from AD-416):
1. Develop and release improved apple rootstocks. 2. Develop and apply genomic and bioinformatic tools to marker-assisted selection of apple rootstocks.

1b. Approach (from AD-416):
Develop and release improved apple rootstocks. Perform all breeding and evaluation stages involved in the 15-25 year process of developing new rootstocks with the assistance of recently developed breeding tools, such as marker-assisted selection. Develop improved propagation methods that speed the distribution of selected material to customers through established networks of cooperating nurseries. Exogenous treatments of layering propagation stool beds will increase adventitious root formation and quality of nursery liners. Incorporate innovative concepts of orchard establishment and management including mechanization. Existing experimental rootstocks in the breeding pipeline possess adaptations for novel orchard concepts and mechanization. Develop and apply genomic and bioinformatic tools to marker-assisted selection of apple rootstocks. Develop algorithms to assist with identifying specific markers for priority horticultural traits from the large body of expressed sequence tags (EST) and genomic sequence data now available.

3. Progress Report:
Planted a new first test research orchard where most of the new rootstocks being evaluated are derived from crosses with disease resistant Malus sieversii accessions from the apple collection. Performed seedling selection with Phytophthora root rot and fire blight inoculations on 10,000 seedlings. Also used DNA markers to cull undesired seedlings that survived inoculations. Fruit production and fruit productivity data collection for apple rootstocks breeding lines was hampered by the early Spring bloom (3 weeks earlier than normal) and subsequent frosts that hit the North-East. Observed differences in crop load of some rootstocks and are investigating the connection with the frost events. The program received positive reports on the performance of several elite and released Geneva rootstocks at several U.S. and international collaborative trials. To understand how Geneva rootstocks perform under organic management in NY state we planted an on farm trial of several elite rootstocks and commercial rootstock controls. This orchard, situated in the fruit growing region near Lake Ontario is the first one in the region and should shed light on the interaction between rootstocks and organic management. Transferred some elite selections to cooperating nurseries in Western states, to facilitate evaluation in commercial settings and the propagation of more plant material for wider testing. We are making progress with propagation of new selections from the breeding program that will be tested in Geneva, NY. A new potted tree experiment with more than 100 rootstocks grafted with a Spur Red Delicious scion was planted this spring to study the ability of rootstocks to absorb and translocate nutrients from the soil to the fruit.

4. Accomplishments
1. Apple trees need proper nutrition in order to produce good amounts of high quality apples. When fertilizers are applied in the orchard, the root systems of apple rootstocks become the link between the apple tree and the soil that absorbs and provides nourishment to the tree. Apple rootstocks differ in their ability to absorb nutrients. Apple rootstocks that can absorb nutrients from soil more efficiently may provide cost savings to farmers while maintaining productivity and quality. ARS researchers in Geneva, New York and Houston, Texas developed improved rootstocks that absorb and translocate nutrients more efficiently. Also, we found that some nutrients are absorbed together, for example, copper and potassium. This is the first time such research has been reported for apple. So, we are developing new experiments to better understand how this works.

Review Publications
Jensen, P.J., Halbrendt, N., Fazio, G., Makalowska, I., Altman, N., Praul, C., Maximova, S.N., Crassweller, R.M., Travis, J., Mcnellis, T. 2012. Rootstock-regulated gene expression patterns associated with fire blight resistance in apple. Biomed Central (BMC) Genomics. 13:9.

Bai, Y., Doughtery, L., Li, M., Fazio, G., Cheng, L., Xu, K. 2012. A natural mutation led truncation in Ma1, one of the two aluminum-activated malate transporter like genes at the Ma locus, is associated with low fruit acidity in apple. Molecular Genetics and Genomics. 287:563-678.

Last Modified: 06/26/2017
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