National Plant Germplasm System Research Articles

Challenges in the development of a widely applicable method for sugarcane (Saccharum spp.) shoot tip cryopreservation

The USDA-ARS National Plant Germplasm System (NPGS) maintains 946 accessions of sugarcane (Saccharum spp.) in the field at the Subtropical Horticulture Research Station in Miami, Florida. These accessions are particularly vulnerable to hurricanes, diseases, and other threats. We sought to identify a method whereby clonally propagated sugarcane accessions could be successfully introduced into tissue culture, multiplied, and then cryopreserved as shoot tips for long-term preservation at the National Laboratory for Genetic Resources Preservation in Fort Collins, Colorado. For many accessions, 70% isopropyl alcohol and 20% commercial bleach treatments, followed by three rinses of sterile water were sufficient to remove microbial contaminants during the introduction process. However, in some cases, cefotaxime was particularly effective for removing bacterial contamination. We found that antioxidant treatments of glutathione, glycine betaine, and ascorbic acid did not improve regrowth after liquid nitrogen exposure using either PVS2 or PVS3 as cryoprotectants in droplet vitrification cryopreservation methods. Exposure durations of PVS2 and PVS3 were optimized, with and without exposure to liquid nitrogen (LN), and shoot tip regrowth levels ranged from 0 to 37% after LN exposure. Published methods for encapsulation-dehydration and V-plate vitrification cryopreservation procedures were tested to determine if acceptable results could be obtained. Using these methods, shoot tip regrowth levels ranged from 0 to 50% after LN exposure. We conclude that the sugarcane cryopreservation methods that we tested are not yet ready for implementation in the NPGS.

Molecular tools for detecting Pdh1 can improve soybean breeding efficiency by reducing yield losses due to pod shatter

Pod shattering is an ancestral trait that promotes seed dispersal; however, shattering can have substantial yield losses in cultivated soybean. During the improvement process, American soybean breeders virtually eliminated the shatter phenotype for released varieties, but in other countries, such as Ghana, shatter persists. The objective of our research was to find a molecular tool to implicate genetic shatter susceptibility, validate its usefulness, and apply this knowledge to identify shattering potential in parental lines. Previous research revealed the gene Pdh1 on chromosome 16 plays a crucial role in determining the shatter phenotype. A perfect molecular marker assay was developed to detect alleles of the Pdh1 gene. A genome-wide association study (GWAS) was performed using the Pdh1 allele status as a phenotype and identified a highly associated marker in the SoySNP50K array. Soybean accessions from the National Plant Germplasm System (GRIN-NPGS) with shatter score and SoySNP50K data were evaluated to determine the impact of the predicted Pdh1 alleles on early and late pod shattering. An online tool was developed to enable researchers to query the GRIN collection for the predicted Pdh1 allele status. Lines from an African soybean germplasm collection were analyzed, and it was determined that 22.5% of lines had the shatter-susceptible alleles of Pdh1; two of seven Ghanaian released soybean varieties had the shatter-susceptible alleles of Pdh1. Soybean breeding programs that access germplasm from the GRIN or the African collection can utilize these resources to eliminate the Pdh1 effects on pod shatter and thus improve yield potential.

Implementation of Citrus shoot tip cryopreservation in the USDA-ARS National Plant Germplasm System

The USDA-ARS National Plant Germplasm System (NPGS) maintains a citrus genetic resource collection of 1522 accessions of Citrus cultivars and crop wild relatives. Of these, 540 are maintained as pathogen-free duplicate clones in a screenhouse at the National Clonal Germplasm Repository for Citrus and Dates (NCGRCD) in Riverside, California. An additional 815 accessions of citrus and citrus relatives are maintained in greenhouses or orchards in Riverside until sanitation for pathogens can be completed. This paper describes progress in backing up the 540 pathogen-tested accessions using cryopreservation techniques and methods to accelerate processing and viability testing. Vegetative budwood was harvested from trees in the screenhouse and sent to NLGRP. At least 170 shoot tips from each accession were excised from surface-sterilized budwood, and then cryopreserved using a PVS2 droplet-vitrification technique. Viability was assessed by micrografting 10 thawed shoot tips onto in vitro grown 'Carrizo' seedling rootstock. The remaining shoot tips are held in long-term liquid nitrogen storage. A total of 451 of the pathogen-tested citrus accessions were cryoprocessed: 354 accessions had regrowth levels of 40% or greater, 17 had 0% regrowth, 47 had viability levels between 10 and 30%, and 33 had endogenous contaminants. Technical staff familiar with shoot-tip cryoprocessing could be fully trained for specific applications of citrus in about 2 months and thereafter processed a single accession of at least 170 shoot tips in about 16 h. This large-scale effort has revealed that shoot tip cryopreservation can be successfully scaled-up to secure the NPGS Citrus collection.

Variation in floral antioxidant activities and phytochemical properties among butterfly pea (Clitoria ternatea L.) germplasm

Butterfly pea (Clitoria ternatea L.) is a climbing legume grown as a medicinal, ornamental, and forage plant, and used as a natural food colorant. Due to its various medicinal properties in different plant parts, pharmacological potential is evident. However, improvement of the plant for high phytochemical properties has been very limited, hence being pursued. For that improvement effort, butterfly pea germplasm was collected from different parts of Thailand in addition to accessions from 12 other countries acquired from a C. ternatea collection curated by the USDA-Agricultural Research Service National Plant Germplasm System. Characterization and evaluation for phytochemical properties of these germplasm is fundamental for breeding purposes. Floral antioxidant activities (Ferric reducing antioxidant power—FRAP and 2,2-diphenyl-1-picrylhydrazyl—DPPH), total phenolic compound (TPC), total anthocyanin content (TAC), and ascorbic acid content (AAC) were investigated for 126 individuals from 46 accessions of the combined collection. The plants were regenerated from seeds and grown at Kamphaeng Saen, Nakhon Pathom, Thailand, and flowers were harvested in August 2017. Significant differences of TAC and AAC were found among the included accessions. Both variations were correlated with petal color at a moderate level, but not in accordance with geographical locations of the samples. Grouping of the accessions based on antioxidant activities and compounds revealed by cluster and principal component analyses would be useful in the utilization and management of the germplasm for butterfly pea improvement.

Identification of Historic Homestead and Orchard Apple Cultivars in Wyoming

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.

Variation for Salinity Tolerance During Seed Germination in Diverse Carrot [Daucus carota (L.)] Germplasm

Global carrot production is limited by the crop’s high susceptibility to salinity stress. Not much public research has been conducted to screen for genetic salinity stress tolerance in carrot, and few resources exist to aid plant breeders in improving salinity tolerance in carrot. The objectives of this study were to evaluate the response of diverse carrot germplasm to salinity stress, identify salt-tolerant carrot germplasm that may be used by breeders, and define appropriate screening criteria for assessing salt tolerance in germinating carrot seed. Carrot plant introductions (PIs) (n = 273) from the U.S. Department of Agriculture (USDA) National Plant Germplasm System representing 41 different countries, inbred lines from the USDA Agricultural Research Service (n = 16), and widely grown commercial hybrids (n = 5) were screened for salinity tolerance under salinity stress and nonstress conditions (150 and 0 mm NaCl, respectively) by measuring the absolute decrease (AD) in the percent of germination, inhibition index (II), relative salt tolerance (RST), and salt tolerance index (STI) of germinating seeds. All salt tolerance measurements differed significantly between accessions; AD ranged from −4.2% to 93.0%; II ranged from −8.0% to 100.0%; RST ranged from 0.0 to 1.08; and STI ranged from 0.0 to 1.38. Broad sense heritability calculations for these measurements were 0.87 or more, indicating a strong genetic contribution to the variation observed. Six accessions identified as salt-tolerant or salt-susceptible were evaluated in a subsequent experiment conducted at salt concentrations of 0, 50, 100, 150, 200, and 250 mm NaCl. Variations between mean AD, II, RST, and STI of tolerant and susceptible lines were greatest at 150 mm NaCl, validating the use of 150 mm NaCl concentrations during salt tolerance screening of carrot seed. Wild carrot accessions displayed little tolerance, and PI 256066, PI 652253, PI 652402, and PI 652405 from Turkey were most salt-tolerant.

Significant variation for seed oil content, fatty acid profile, and seed weight in natural populations of field pennycress (Thlaspi arvense L.)

Increasing oil content and altering the fatty acid profile of the oilseed cover crop, field pennycress (Thlaspi arvense L.), would improve its profitability and functionality as a biodiesel, and possibly allow its entry into the industrial and edible oil markets. However, plant breeders know little about the amount of existing variation for these traits. To make gains in selection using traditional plant breeding to meet these objectives, heritable variation is required for traits of interest. Reported here is the characterization of a collection of 41 winter type pennycress accessions from the United States Department of Agriculture (USDA) National Plant Germplasm System (NPGS) and wild selections. The collection was grown at three Minnesota locations in 2014–2015 and surveyed for total oil percentage, fatty acid profile, and hundred seed weight. Significant variation (p < 0.001) was detected among the accessions for all traits surveyed. Coupled with high broad sense heritability (average for all traits: Hplot2=0.62 and Hentry2=0.88), results indicate potential for effective selection within this collection in the environments tested. Although significant, no extreme variation was found, suggesting that mutagenesis or additional germplasm may be necessary to make desired alterations. The effect of location was significant for nine of twelve traits, and accession by location interaction in eight of twelve, showing that both overall and relative performance of the accessions were variable across locations.

Short- and medium-term in vitro conservation and management of germplasm within the USDA’s National Plant Germplasm System

Seed banking remains the primary strategy for germplasm conservation. However, for selected species, in vitro shoot cultures constitute an important tool in the preservation of germplasm. Although cryopreservation is the preferred method of long-term conservation, short- and medium-term preservation with in vitro shoot cultures remains a workable and flexible option. In addition, rapid in vitro multiplication of plants collected in the wild prior to seed set can provide bulked material for seed production in common garden settings. Here I describe the approaches used for preservation and management of selected germplasm using shoot culture techniques within the National Plant Germplasm System of the United States Department of Agriculture. Specific example will be made of the work at the Ornamental Plant Germplasm Center on the development of tissue culture preservation systems for herbaceous ornamental genera, such as Phlox and Begonia.

Chloroplast sequence data differentiate Maleae, and specifically Pyrus, species in the USDA-ARS National Plant Germplasm System

The USDA-ARS National Plant Germplasm System (NPGS) maintains a large collection of Maleae, including 49 Malus taxa, 36 Pyrus taxa, and 24 additional genera with ornamental and plant breeding value. These plant genetic resources are primarily maintained clonally as trees or shrubs in field conditions, and seeds are also conserved for some species. We used NPGS Maleae taxa to assess the genetic diversity across the tribe Maleae and placed Pyrus taxa within this broader context using analytical methods that displayed the genetic relationships as a network, rather than as a traditional dendrogram. Sequence variation from four conserved chloroplast regions unraveled the complex and often reticulate genetic relationships among and within 109 economically important Maleae taxa. In a broad sense, chloroplast haplotypes differentiated Pyrus species within Sections Pyrus and Pashia. The genetic relationships amongst Pyrus species were found to be complex, likely resulting from multiple hybridization and expansion/contraction events during the speciation process. Knowledge of the genetic relationships among Maleae genera and/or species may aid in the selection of materials for use as rootstocks and or breeding (hybridization) programs. Future collection efforts to augment the NPGS accessions within the tribe Maleae will improve the coverage and representation and assure conservation of important Rosaceae genetic resources in the NPGS.

The USDA cucumber (Cucumis sativus L.) collection: genetic diversity, population structure, genome-wide association studies, and core collection development

Germplasm collections are a crucial resource to conserve natural genetic diversity and provide a source of novel traits essential for sustained crop improvement. Optimal collection, preservation and utilization of these materials depends upon knowledge of the genetic variation present within the collection. Here we use the high-throughput genotyping-by-sequencing (GBS) technology to characterize the United States National Plant Germplasm System (NPGS) collection of cucumber (Cucumis sativus L.). The GBS data, derived from 1234 cucumber accessions, provided more than 23 K high-quality single-nucleotide polymorphisms (SNPs) that are well distributed at high density in the genome (~1 SNP/10.6 kb). The SNP markers were used to characterize genetic diversity, population structure, phylogenetic relationships, linkage disequilibrium, and population differentiation of the NPGS cucumber collection. These results, providing detailed genetic analysis of the U.S. cucumber collection, complement NPGS descriptive information regarding geographic origin and phenotypic characterization. We also identified genome regions significantly associated with 13 horticulturally important traits through genome-wide association studies (GWAS). Finally, we developed a molecularly informed, publicly accessible core collection of 395 accessions that represents at least 96% of the genetic variation present in the NPGS. Collectively, the information obtained from the GBS data enabled deep insight into the diversity present and genetic relationships among accessions within the collection, and will provide a valuable resource for genetic analyses, gene discovery, crop improvement, and germplasm preservation.

Oil concentration and fatty-acid profile of naturalized Helianthus annuus populations from Australia

Although wild annual sunflower (Helianthus annuus L.) is indigenous to North America, it has been both inadvertently and intentionally introduced into other countries, such as Australia, where it has become naturalized. Prior to this research, there were no collections of naturalized H. annuus from Australia in the USDA National Plant Germplasm System gene bank. The possibility exists that naturalized Australian populations may contain distinct traits, such as oil content and fatty-acid composition, differing from their North American progenitors due to the different environments, diseases, and insect-pest complexes. The objective of this study was to collect naturalized H. annuus populations from the five states of Australia and to analyze them for oil content and fatty-acid composition. Fifty-six populations were collected throughout the broad distributional range of this species and then analyzed for oil content and fatty-acid composition. The mean oil content of the H. annuus populations was 28%, ranging from a low of 19% to a high of 31%, similar to populations of this species in its native North American habitats. Fatty-acid profiles were also similar for North American wild populations, Australian naturalized populations, and improved cultivars. Oil concentration of hybrids can be rapidly increased to acceptable levels by backcrossing with cultivated sunflower. Based on this fact, there should be little concern about the relatively low oil content of these naturalized populations when they are used as a source of other unique traits for cultivated sunflower improvement.

Crop Science Society of America Celebrates First Annual Crop Wild Relative Week, September 22–29, 2018

Crop Science Society of America Celebrates First Annual Crop Wild Relative Week, September 22–29, 2018

Molecular identification and characterization of endophytes from uncultivated barley

ABSTRACTEpichloë species (Clavicipitaceae, Ascomycota) are endophytic symbionts of many cool-season grasses. Many interactions between Epichloë and their host grasses contribute to plant growth promotion, protection from many pathogens and insect pests, and tolerance to drought stress. Resistance to insect herbivores by endophytes associated with Hordeum species has been previously shown to vary depending on the endophyte-grass-insect combination. We explored the genetic and chemotypic diversity of endophytes present in wild Hordeum species. We analyzed seeds of Hordeum bogdanii, H. brevisubulatum, and H. comosum obtained from the US Department of Agriculture’s (USDA) National Plant Germplasm System (NPGS), of which some have been reported as endophyte-infected. Using polymerase chain reaction (PCR) with primers specific to Epichloë species, we were able to identify endophytes in seeds from 17 of the 56 Plant Introduction (PI) lines, of which only 9 lines yielded viable seed. Phylogenetic analyses of housekeeping, alkaloid biosynthesis, and mating type genes suggest that the endophytes of the infected PI lines separate into five taxa: Epichloë bromicola, Epichloë tembladerae, and three unnamed interspecific hybrid species. One PI line contained an endophyte that is considered a new taxonomic group, Epichloë sp. HboTG-3 (H. bogdanii Taxonomic Group 3). Phylogenetic analyses of the interspecific hybrid endophytes from H. bogdanii and H. brevisubulatum indicate that these taxa all have an E. bromicola allele but the second allele varies. We verified in planta alkaloid production from the five genotypes yielding viable seed. Morphological characteristics of the isolates from the viable Hordeum species were analyzed for their features in culture and in planta. In the latter, we observed epiphyllous growth and in some cases sporulation on leaves of infected plants.

Population and quantitative genomic properties of the USDA soybean germplasm collection

AbstractThis study is the first assessment of the entire soybean [Glycine max(L.) Merr] collection of the United State Department of Agriculture National Plant Germplasm System (USDA) reporting quantitative and population genomic parameters. It also provides a new insight into soybean germplasm structure. Germplasm studies enable plant breeders to incorporate novel genetic resources into breeding pipelines to improve valuable agronomic traits. We conducted comprehensive analyses on the 19,652 soybean accessions in the USDA-ARS germplasm collection, genotyped with the SoySNP50 K iSelect BeadChip SNP array, to elucidate the quantitative properties of existing subpopulations inferred through hierarchical clustering performed with Ward'sDagglomeration method and Nei's standard genetic distance. We found the effective population size to be approximately 106 individuals based on the linkage disequilibrium of unlinked loci. The cladogram indicated the existence of eight major clusters. Each cluster displays particular properties with regard to major quantitative traits. Among those, cluster 3 represents the tropical and semi-tropical genetic material, cluster 5 displays large seeds and may represent food-grade germplasm, and cluster 7 represents the undomesticated material in the germplasm collection. The averageFSTamong clusters was 0.22 and a total of 914 SNPs were exclusive to specific clusters. Our classification and characterization of the germplasm collection into major clusters provides valuable information about the genetic resources available to soybean breeders and researchers.

Genetic diversity of dihydrochalcone content in Malus germplasm

Dihydrochalcones, beneficial phenolic compounds, are abundant in Malus Mill. species, particularly in vegetative tissues and seeds. Phloridzin (phloretin 2′-O-glucoside) is the primary dihydrochalcone in most Malus species including cultivated apple, Malus × domestica Borkh. A few species contain sieboldin (3-hydroxyphloretin 4′-O-glucoside) or trilobatin (phloretin 4′-O-glucoside) in place of phloridzin, and interspecific hybrids may contain combinations of phloridzin, sieboldin, and trilobatin. Proposed health benefits of phloridzin include anti-cancer, antioxidant, and anti-diabetic properties, suggesting the potential to breed apples for nutritional improvement. Sieboldin and trilobatin are being investigated for nutritional value and unique chemical properties. Although some of the biosynthetic steps of dihydrochalcones are known, little is known about the extent of variation within Malus germplasm. This research explores the genetic diversity of leaf dihydrochalcone content and composition in Malus germplasm. Dihydrochalcone content was measured using high performance liquid chromatography (HPLC) from leaf samples of 377 accessions, representing 50 species and interspecific hybrids from the USDA-Agricultural Research Service (ARS) National Plant Germplasm System Malus collection. Within the accessions sampled, 284 accessions contained phloridzin as the primary dihydrochalcone, one had only trilobatin, two had phloridzin and trilobatin, 36 had sieboldin and trilobatin, and 54 had all three. Leaf phloridzin content ranged from 17.3 to 113.7 mg/g with a heritability of 0.76 across all accessions. Beyond the potential of dihydrochalcones for breeding purposes, dihydrochalcone composition may be indicative of hybridization or species misclassification.

Sustaining the Future of Plant Breeding: The Critical Role of the USDA‐ARS National Plant Germplasm System

Plant breeders require genetic diversity to develop cultivars that are productive, nutritious, tolerant of biotic and abiotic stresses, and make efficient use of water and fertilizer. The USDA‐ARS National Plant Germplasm System (NPGS) is a major source for global plant genetic resources (PGR), with accessions representing improved cultivars, breeding lines, landraces, and crop wild relatives (CWR), coupled with passport and trait evaluation data. The goal of this article is to facilitate use of PGR in plant breeding programs. Our specific objectives are (i) to summarize the structure and operation of the NPGS and its consultative and support committees, (ii) to review current use of the system by plant breeders, (iii) to describe constraints to improving the utility of PGR, and (iv) to discuss ways in which the NPGS might evolve to better meet the challenges facing agriculture and society in coming decades. The NPGS will enhance its relevance to plant breeding provided there is (i) ongoing attention to filling the gaps in NPGS collections, especially for CWR; (ii) a major increase in efforts to phenotype and genotype accessions using standardized methods; (iii) enhanced information content of the Genetic Resources Information Network (GRIN)‐Global system and improved interoperability with other databases; (iv) increased attention to prebreeding activities; (v) improved training opportunities in practices for incorporating PGR in breeding programs; and (vi) expanded outreach efforts to strengthen public support for the NPGS. We believe these steps will be implemented most effectively through coordinated efforts among USDA‐ARS, universities, the private sector, and international partners.

Population structure of the NPGS Senegalese sorghum collection and its evaluation to identify new disease resistant genes.

Sorghum germplasm from West and Central Africa is cultivated in rainy and high humidity regions and is an important source of resistance genes to fungal diseases. Mold and anthracnose are two important biotic constraints to sorghum production in wet areas worldwide. Here, 158 National Plant Germplasm System (NPGS) accessions from Senegal were evaluated for agronomic traits, anthracnose, and grain mold resistance at two locations, and genetically characterized according to 20 simple sequence repeat markers. A total of 221 alleles were amplified with an average of 11 alleles per locus. Each accession had a unique genetic profile (i.e., no duplicates), and the average genetic distance between accessions was 0.42. Population structure and cluster analysis separated the collection into four populations with pairwise FST values >0.15. Three of the populations were composed of Guinea-race sorghum germplasm, and one included multiple races. Anthracnose resistant accessions were present at high frequency and evenly distributed among the three Guinea-race populations. Fourteen accessions showed resistance to grain mold, and eight were resistant to both diseases. These results indicated that the NPGS of Senegal is a genetically diverse collection with a high frequency of disease resistant accessions. Nevertheless, its population structure suggests the presence of few sources of resistance to both grain mold and anthracnose, which are fixed in the germplasm. The phenotypic and genotypic information for these accessions provides a valuable resource for its correct use to broaden the genetic base of breeding programs.

Agapetes: jewels from the Himalayas

The U.S. Department of Agriculture, National Clonal Germplasm Repository (NCGR) at Corvallis, Oregon, maintains genetic resources for temperate specialty crops. This genebank houses crop wild relatives of Vaccinium L., including Agapetes D. Don ex G. Don. Agapetes is a semi-climbing, epiphytic woody shrub native to Southeastern Asia. It is found in the Himalayan highlands from India and Nepal through China to Vietnam, Laos, and Thailand. From 25 October to 14 November 2015, Agapetes and other relatives were collected during a Vietnamese-U.S. cooperative expedition in Northern Vietnam. The exploration involved scientists of the Plant Resources Center, Vietnam Academy of Agricultural Sciences in Hanoi, and the NCGR. The exploration was supported through the U.S. National Plant Germplasm System (NPGS) Plant Exploration/Exchange Program. Permissions for collecting were obtained from the Vietnamese Ministry of Agriculture and Rural Development, and the administration of four Vietnamese National Parks. During the expedition, five species of Agapetes were collected, doubling the number of species represented in the NCGR. Root samples for propagation and seeds were collected from 1200 to 3100 m elevation. Chilling hours in these habitats were estimated to be 50-160 h year-1. Agapetes species were lithophytic (rock-growing) or epiphytic. The plants simultaneously displayed multiple stages of phenology from bud break to fruit development. Fruit colors of Agapetes included pink, bright red, fuchsia, purple, and black. Descriptive flower and fruit characters of the Agapetes in the NCGR collection will be summarized.

Prioritization ofMalusaccessions for collection cryopreservation at the USDA-ARS National Center for Genetic Resources Preservation

The USDA-ARS National Plant Germplasm System maintains a grafted collection of apple accessions representing 48 taxa in Geneva, NY. Dormant buds of many of these accessions have been routinely cryopreserved at the USDA-ARS National Center for Genetic Resources Preservation (NCGRP) in Fort Collins, CO. In the standard procedure, dormant buds are sent to NCGRP in mid-winter. Scions are cut into 35 mm bud sections and desiccated at -5°C to a moisture content of 25 to 30% (fresh weight basis). Desiccated single-bud sections are then sealed into polyolefin tubes containing 10 to 12 sections each, slow cooled at -1°C h-1 to -30°C, held at -30°C for 24 h, and then placed into the vapor phase of liquid nitrogen (LNV) for long term storage. For viability testing, the buds from one polyolefin tube are rehydrated at 2°C in moist, sterile peat moss and grafted onto rootstocks. For most accessions, this left 3 polyolefin tubes of Malus buds in long-term storage for each accession. For this analysis, successfully cryopreserved accessions were defined as those that have a total of 19 or more predicted viable buds remaining in LNV at NCGRP. Of the 2291 accessions currently cryopreserved at NCGRP, 2052 accessions meet this requirement. Criteria were established to prioritize the apple accessions that are either inadequately backed up at NCGRP or have not yet been processed. These criteria include the likelihood of success in cryopreserving the Malus taxon, the vulnerability of the field trees, the number of viable buds currently stored in LNV, and previous failures in response to the standard procedure.

U.S. ratification of Plant Treaty: benefit sharing ambiguity for plant genomics researchers does not change

Plant genomics data and information are widely acknowledged to have potential benefits for plant breeding and global food security. Yet, at present, there is a great deal of confusion over potential benefit sharing obligations arising from use of genomics data and information, particularly if the data and information are derived from plant genetic resources accessed from gene banks that are part of the International Treaty on Plant Genetic Resources in Food and Agriculture (Treaty) Multilateral System (MLS). To some extent, this lack of clarity stemmed from the fact that the U.S. Department of Agriculture’s National Plant Germplasm System was not, until recently, part of the Treaty MLS. In October 2016, however, the U.S. ratified the Treaty. This paper addresses whether the U.S. ratification of the Treaty has ameliorated or exacerbated the confusion. In reviewing Treaty benefit sharing obligations and their impact on plant genomics pre- and post-U.S. ratification, it appears that ambiguity around genomics data and information is largely unchanged. In light of this, the paper recommends further dialogue about this important issue.