Germplasm Collection of Malus sieversii from Central Asia Is Well-preserved in the USDA-ARS National Plant Germplasm System

Malus sieversii is the primary wild progenitor of cultivated apples and has many desirable traits and genes for future improvement of apple cultivars. Herb Aldwinckle, Phil Forsline, and others collected M. sieversii germplasm from Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan in their 1989, 1993, 1995, and 1996 explorations. Majority of the materials were collected in the form of open-pollinated seeds. Forty-four “Kazakhstan Elite” budwood were also collected and brought back to the U.S. through the APHIS quarantine program. Wild Malus germplasm in Central Asia is facing severe degradation resulting from human disturbance of the natural habitat such as fire-wood gathering and it could be largely eliminated in next 50-150 years. Fortunately the M. sieversii germplasm from the past explorations has been evaluated and well maintained at the ARS Plant Genetic Resources Unit (PGRU) in Geneva, NY. Seeds of M. sieversii were germinated, planted, and evaluated, and the desirable seedlings were selected on the basis of disease screening, genetic diversity, drought stress resistance, and overall performance at the University of Minnesota, Ohio State University, and PGRU. Seventy-nine, 12, and 263 seedlings were selected by these three sites, respectively. A total of 354 M. sieversii selected seedlings are now permanently preserved at PGRU and their budwood are available for distribution. There are 868 M. sieversii seed accessions with a total of 57,377 seeds stored at a -20⁰C freezer at PGRU and most of them are from the explorations. Many of these seed accessions (271) have also been stored as backup at the National Center for Genetic Resources Preservation (NCGRP), USDA-ARS, Fort Collins, CO. In total, there are 288 M. sieversii seed accessions with 40,662 seeds stored at NCGRP. We also had 49,365 seeds collected from controlled crosses among M. sieversii seedlings at PGRU from 2004-2006. Furthermore, over 110,000 open pollinated seeds from M. sieversii seedling block (also called the “Botany of Desire Seeds”) were collected from 2002-2015 at PGRU and are available for distribution. Additional M. sieversii seedling evaluation continues at Ohio State University, University of Arkansas, and PGRU. Overall, the germplasm resource of wild M. sieversii from Central Asia is well preserved in the U.S. National Plant Germplasm System.