Ex situ conservation of vegetatively propagated species:: Development of a seed-based core collection for Malus sieversii

Seeds and scionwood of Malus sieversii Lebed. 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 each of 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 35 trees within each population will be used as parents in crosses so that the genetic diversity in the orchard 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.