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Title: Diversity of wild Malus germplasm available in the USDA-ARS National Plant Germplasm System

Author
item Volk, Gayle
item Richards, Christopher
item Forsline, Philip

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/17/2008
Publication Date: 9/17/2008
Citation: Volk, G.M., C.M. Richards, Aldwinckle, H.2008. Diversity of wild Malus germplasm available in the USDA-ARS National Plant Germplasm System. American Society for Horticultural Science. Annual Conference. July 21-24, 2008. Orlando, FL. 43:1136. Meeting Abstract.

Interpretive Summary: Plant explorers have visited Russia, Turkey, Kazakhstan, and China over the past twenty years to find populations of the wild relatives of apple (Malus). Seeds from wild populations of M. sieversii, M. orientalis, M. hupehensis, M. kansuensis, M. toringo, M. bhutanica, M. transitoria, and M. zhaojiaoensis have been planted at the USDA-ARS-National Plant Germplasm System (NPGS) Plant Genetic Resources Unit in Geneva, NY. Malus sieversii and M. orientalis seedling trees have been screened for disease resistance and evaluated for genetic diversity based on microsatellite markers and ploidy levels have been identified for the species native to China. Genetic diversity analyses reveal that most of the overall genetic structure in these species is partitioned among individual families but that significant regional differentiation exists. Some accessions exhibit high levels of resistance to apple scab (Venturia inaequalis Cooke), cedar apple rust (Gymnosporangium juniperi-virginianae Schwein) as well as fire blight (Erwinia amylovora Burrill) and could be very valuable in disease resistance breeding programs. Genotypic data for microsatellite markers is publicly available in the new molecular observation tables in the Germplasm Resources Information Network (GRIN) database (http://www.ars-grin.gov/npgs/).

Technical Abstract: Plant explorers have visited Russia, Turkey, Kazakhstan, and China over the past twenty years to find populations of the wild relatives of apple (Malus). Seeds from wild populations of M. sieversii, M. orientalis, M. hupehensis, M. kansuensis, M. toringo, M. bhutanica, M. transitoria, and M. zhaojiaoensis have been planted at the USDA-ARS-National Plant Germplasm System (NPGS) Plant Genetic Resources Unit in Geneva, NY. Malus sieversii and M. orientalis seedling trees have been screened for disease resistance and evaluated for genetic diversity based on microsatellite markers and ploidy levels have been identified for the species native to China. Genetic diversity analyses reveal that most of the overall genetic structure in these species is partitioned among individual families but that significant regional differentiation exists. Some accessions exhibit high levels of resistance to apple scab (Venturia inaequalis Cooke), cedar apple rust (Gymnosporangium juniperi-virginianae Schwein) as well as fire blight (Erwinia amylovora Burrill) and could be very valuable in disease resistance breeding programs. Genotypic data for microsatellite markers is publicly available in the new molecular observation tables in the Germplasm Resources Information Network (GRIN) database (http://www.ars-grin.gov/npgs/).