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Apples (Malus Mill.) have been economically and socially important throughout the centuries in North America. Apple cultivar (Malus ×domestica Borkh.) collections that include historic cultivars are valued for their unique diversity, historical significance, and also as a resource to identify unknown trees; however, not all of the historically significant apple cultivars are currently included in these collections. We used historic books, publications, and nursery catalogs to develop an inventory of apple cultivars that were propagated and grown in the United States before 1908. We collected synonym, introduction date, and original source country information for 891 historic apple cultivars. Most of the historic American cultivars originated as seedlings first planted in the United States. Some cultivars were brought to the United States from the United Kingdom, France, Russia, Germany, and other European countries. We classified historic apple cultivars based on their availability over time and popularity in nursery catalogs. Ninety percent of the most popular historic apple cultivars in the United States were available in 2015 in the U.S. and U.K. national collections and within several commercial and private collections. This work identified high priority historic cultivars that are not currently protected within genebanks that could be added to genebank collections in the future.
Thousands of apple trees were planted in Wyoming’s orchards and homesteads in the 1800s, many of which are still alive today. Unfortunately, cultivar identity of these trees has mostly been lost or obscured. The purpose of this research was to identify heritage apple cultivars in Wyoming using genetic fingerprinting (microsatellite) techniques and to use this information to make recommendations on candidate cold-hardy cultivars for specialty crop and breeding programs. Leaf samples were collected from 510 heritage apple trees from 91 sites in 19 locales across Wyoming. Known cultivars from the U.S. Department of Agriculture (USDA)–National Plant Germplasm System, Seed Savers Exchange, and Washington State University apple collections were used as standards to determine cultivar identities. Overall, 328 (64%) of the previously unidentified apples trees were identified to 47 known cultivars. Fifteen of these known cultivars comprised more than 80% of the samples that were identified, with all 15 of those cultivars developed in states and countries with average temperatures or winter conditions similar to Wyoming. Seventy-one of the heritage trees were identified as the Wealthy cultivar. Other commonly identified cultivars were Haralson, Patten’s Greening, Yellow Transparent, Northwestern Greening, and McMahon. It is likely that a combination of popularity and cultivar origin affected the choice of cultivars that were grown in Wyoming. Although most original Wyoming heritage apple trees are reaching the end of their life span, many surviving trees continue to produce fruit. This strongly suggests that despite lower resistance to certain pathogens than many modern cultivars, these heritage trees should be considered for use today. The results provide insights into possible cultivars that could be grown in Wyoming and also in other states with similar harsh growing conditions.
Garlic (Allium sativum L.) has been clonally propagated for thousands of years because it does not produce seed under standard cultivation conditions. A single garlic accession frequently displays a high degree of phenotypic plasticity that is likely to be dependent upon soil type, moisture, latitude, altitude, and cultural practices. The diversity observed by collectors has occasionally led to the renaming of varieties as they are exchanged among growers and gardeners. As a result, there are numerous garlic varieties available both commercially and within the USDA National Plant Germplasm System (NPGS) that may be identical genotypically, yet have unique cultivar names. To address this possibility, we performed amplified fragment-length polymorphism (AFLP) analysis on a comprehensive selection of 211 Allium sativum and Allium longicuspis accessions from NPGS and commercial sources. We used several statistical approaches to evaluate how these clonal lineages are genetically differentiated and how these patterns of differentiation correspond to recognized phenotypic classifications. These data suggest that while there are extensive duplications within the surveyed accessions, parsimony and distance based analyses reveal substantial diversity that is largely consistent with major phenotypic classes.
Edible European pears (Pyrus communis sp. communis L.) are thought to be derived from wild relatives native to the Caucasus Mountain region and eastern Europe. We collected genotype, phenotype, and geographic origin data for 145 P. communis individuals derived from seeds collected from wild relatives. These individuals are currently maintained in the USDA–ARS National Plant Germplasm System (NPGS) in Corvallis, Ore. Pear genotypes were obtained using 13 microsatellite markers. A Bayesian clustering method grouped the individual pear genotypes into 12 clusters. The subspecies of pears native to the Caucasus Mountains of Russia, Crimea, and Armenia could be genetically differentiated from the subspecies native to eastern European countries. Pears with large fruit clustered closely together and are most closely related to a group of genotypes that are intermediate to the other groups. Based on the high number of unique alleles and heterozygosity in each of the 12 clusters, we conclude that the genetic diversity of wild P. communis is not fully represented in the NPGS
There are several Central Asian Malus species and varieties in the USDA-ARS National Plant Germplasm System (NPGS) apple collection. Malus sieversii is the most comprehensively collected species native to Central Asia. Other taxa such as M. sieversii var. kirghisorum, M. sieversii var. turkmenorum, M. pumila, and M. pumila var. niedzwetzkyana have primarily been donated to the collection by other institutions and arboreta. We sought to determine if genetic and/or phenotypic differences among the individuals that make up the gene pools of these taxa in the NPGS exhibit unique characteristics. Genetic data, based on microsatellite analyses, suggested that the diversity within each taxa is significantly greater than that among taxa. Trait data also revealed very few differences among taxa, the primary characteristic being the dark red fruit coloration and tinted flesh color of the accessions assigned to M. pumila var. niedzwetzkyana resulting from a known single-gene mutation in anthocyanin production. We found that M. sieversii is a highly diverse species with a range in genetic and phenotypic trait variation that includes the characteristics of the other Central Asian taxa of interest. We conclude that the gene pools that comprise the accessions within the NPGS Central Asian Malus collection are highly overlapping with respect to both phenotypic traits and genotypic characters.
Many apple varieties commonly planted in the United States a century ago can no longer be found in today's orchards and nurseries. Abandoned farmsteads and historic orchards harbor considerable agrobiodiversity, but the extent and location of that diversity is poorly understood. We assessed the genetic diversity of 280 apple (Malus ×domestica Borkh.) trees growing in 43 historic farmstead and orchard sites in Arizona, Utah, and New Mexico using seven microsatellite markers. We compared the samples to 109 cultivars likely introduced into the southwest in the late 19th and early 20th centuries. Genetic analysis revealed 144 genotypes represented in the 280 field samples. We identified 34 of these 144 genotypes as cultivars brought to the region by Stark Brothers Nursery and by USDA agricultural experiment stations. One hundred twenty of the total samples (43%) had DNA fingerprints that suggested they were representative of these 34 cultivars. The remaining 160 samples—representing 110 genotypes—had unique fingerprints that did not match any of the fingerprinted cultivars. The results of this study confirm for the first time that a high diversity of historic apple genotypes remain in homestead orchards in the U.S. southwest. Future efforts targeting orchards in the southwest should focus on conservation for all unique genotypes as a means to sustain both cultural heritage and biological genetic diversity.
The genetic diversity of a wild Malus population collected in the Kyrgyz Republic was compared with seedlings of Malus sieversii collected in Kazakhstan. Based on microsatellite marker results, we conclude that the population of 49 individuals collected in the Kyrgyz Republic includes private alleles and this population is assigned to a common genetic lineage with M. sieversii individuals found in the Karatau Mountain range of Kazakhstan. We recommend that a subset of these individuals be included in the National Plant Germplasm System Malus collection so they may be made available to breeders, physiologists, and other scientists for further examination.
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.
Edible european pears (Pyrus communis L. ssp. communis) are derived from wild relatives native to the Caucasus Mountain region and eastern Europe. Microsatellite markers (13 loci) were used to determine the relationships among 145 wild and cultivated individuals of P. communis maintained in the National Plant Germplasm System (NPGS). A Bayesian clustering method grouped the individual pear genotypes into 12 clusters. Pyrus communis ssp. caucasica (Fed.) Browicz, native to the Caucasus Mountains of Russia, Crimea, and Armenia, can be genetically differentiated from P. communis ssp. pyraster L. native to eastern European countries. The domesticated pears cluster closely together and are most closely related to a group of genotypes that are intermediate to the P. communis ssp. pyraster and the P. communis ssp. caucasica groups. Based on the high number of unique alleles and heterozygosity in each of the 12 clusters, we conclude that genetic diversity of wild P. communis is not fully represented at the NPGS. Additional diversity may be present in seed accessions stored in the NPGS and more pear diversity could be captured through supplementary collection trips to eastern Europe, the Caucasus Mountains, and the surrounding countries.
Genetic diversity and disease resistance are described for 496 seedlings from wild populations of Malus orientalis Uglitzh. collected in southern Russia and Turkey in 1998 and 1999. Eighty-five half-sib families were genotyped using seven microsatellite markers, and disease resistance was determined for apple scab (Venturia inaequalis Cooke), cedar apple rust (Gymnosporangium juniperi-virginianae Schwein), and fire blight (Erwinia amylovora Burrill). Individuals from the two Russian Caucasus collection locations were homogeneous compared with populations from the four Turkish collection locations. Within three of the Turkish collection locations, some half-sib families were highly diverse and several of these families had unusually high levels of disease resistance. In all, twenty individuals exhibited resistance to all three diseases. Bayesian analyses of the population structure revealed six distinct clusters. Most of the individuals segregated into two clusters, one containing individuals primarily from southern Russia and the other containing individuals from both Russia and northern Turkey. Individuals in the four small clusters were specific to Turkish collection locations. These data suggest wild populations of M. orientalis from regions around the Black Sea are genetically distinguishable and show high levels of diversity.