Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2004
Publication Date: 3/1/2005
Citation: Volk, G.M., A. Reilley, A.D. Henk, P.L. Forsline, H.S. Aldwinckle, and C.M. Richards. 2005. Ex situ conservation of vegetatively-propagated species: development of a seed-based core collection for Malus sieversii. Journal of the American Society of Horticultural Science. 130:203-210. Interpretive Summary: Malus sieversii is a wild relative of most common apple cultivars. M. sieversii grows in deciduous forests in Kazakhstan, its center of origin. USDA researchers have collected seeds and budwood from these wild trees and they are growing at the USDA Plant Genetic Resources Unit in Geneva, N.Y. We performed a genetic study using the plant materials from two collection sites in Kazakhstan. Using molecular data and information collected on disease resistance and fruit characteristics, we identified representative subsets of 35 trees from each of the two collection sites. We have also described a method that can be used to cross within these sets of 35 trees so the genetic diversity of these collections can be captured in the form of seeds. Seed collections can be easily stored and distributed to users. It is more economical to maintain these wild collections of trees in the form of seeds, rather than as orchard plantings.
Technical Abstract: Seeds and scionwood of Malus sieversii have been collected from wild populations of apple trees in Kazakhstan. Seedlings and grafted trees were planted in the orchards at the U.S. Dept. of Agriculture Plant Genetic Resources Unit in Geneva, N.Y. We developed core collections to capture the genetic and phenotypic diversity represented in the trees from two of the Kazakhstan collection sites. These core collections capture more than 90% of the genetic diversity of the original populations as determined using seven unlinked simple sequence repeat markers and 19 quantitative traits. Since phenotypic evaluations of these materials have been completed, the thirty-five trees within each population will be used as parents in crosses so that the genetic diversity within in these populations can be captured as seed for long term ex situ conservation. This strategy of storing seeds, rather than maintaining costly field collections, could be applied to other collections of wild plant materials in the National Plant Germplasm System.