Introduction Of Germplasm Research Articles

Genetic Diversity Patterns in Japanese Soybean Cultivars Based on Coefficient of Parentage

Japan is a historical center of genetic diversity for soybean [Glycine max (L.) Merr.], but diversity of modern Japanese cultivars is not well characterized. The objectives of this study were to quantify genetic diversity of Japanese cultivars via coefficient of parentage (CP), determine the relative importance of breeding factors in explaining that diversity, and incorporate results into a practical guide for management of diversity. All 86 public Japanese cultivars released and registered during 1950 to 1988 were subjected to CP and multivariate analysis. The mean CP for the 86 cultivars was low (0.04), indicating a potentially high degree of diversity in Japanese breeding. Eighty percent of all pairs of cultivars were completely unrelated by pedigree. The low mean CP for the cultivars was attributed to a continual incorporation of unique Japanese land races into the genetic base over time, to the introduction of foreign germplasm from China and the United States and Canada (US-CAN) as breeding stock, and to limited exchange of germplasm among Japanese breeding programs. Cluster analysis was an effective discriminator of diversity. Six clusters were identified which had a mean CP value equivalent to that of half-sibs or greater. These clusters encompassed a total of 54 cultivars, explained 57% of the variation in the CP relations, and had few ancestors in common. Each cluster was derived primarily from only a few programs. Backcrossing and full-sib matings were absent in Japanese pedigrees and, thus, clusters were formed primarily from parent-offspring, full-sib, and half-sib relations. Cultivar attributes such as growing region, release era, maturity designation, and developing institution did not elucidate strong patterns of pedigree diversity. In practical breeding, one may maximize the chances of finding good specific Japanese × Japanese or Japanese × US-CAN crosses by choosing Japanese cultivars from a wide array of Japanese clusters rather than sampling extensively within a cluster.

Genetic diversity within Australian wheat breeding programs based on molecular and pedigree data

124 wheat cultivars and breeding lines were screened with 19 microsatellite (SSR) loci generating 160 scorable bands which were used to construct a genetic distance (GD) matrix. A distance matrix based on coefficient of parentage (COP) scores was also generated for the cultivars for which good pedigree records were available. The SSR and COP data for 101 of the wheat cultivars were compared with genetic distance scores obtained using1898 scorable restriction fragment length polymorphism (RFLP) bands previously generated. Phylograms were generated based on the SSR, RFLP,combined SSR and RFLP and COP data. The standardised Mantel's Z test showed that the distance matrices generated from all of the data sets were significantly correlated. Bootstrap analysis showed that, although the SSR and RFLP data were correlated, a large number of SSR loci are required for determining robust genetic relationships between large numbers of cultivars. In addition, accurate pedigree records are needed to determine genetic relatedness using COP. The molecular data were also used to determine the level of genetic variability within breeding programs and to assess the impact of the introduction of semidwarf and other germplasm. The results showed that the level of genetic diversity in Australian wheat cultivars has increased over time and that in particular, the introduction of semidwarf germplasm resulted in an increase in the overall diversity.

Peanut resistance to Sclerotinia minor and S. sclerotiorum

The fungi Sclerotinia minor and S. sclerotiorum are the causal agents of two similar diseases of peanut (Arachis hypogaea L.). Both diseases cause significant losses in the Australian peanut industry. Development of cultivars with resistance to Sclerotinia will be an important component of integrated control. The aims of this project are to generate information that will assist in breeding for Sclerotinia resistance in peanut: to identify Sclerotinia-resistant peanut germplasm, to understand the inheritance and estimate heritability of resistance, and to test the effectiveness of identified sources of resistance against both S. minor and S. sclerotiorum. This study has clearly established that material that shows resistance to S. minor in the USA is resistant to S.�minor and likely to be resistant to S. sclerotiorum in Australia. The high level of resistance to both S. minor and S.�sclerotiorum in germplasm from Texas, particularly TxAG-4, was confirmed. VA 93B showed good resistance in the field, which is primarily due to the open bush type rather than physiological resistance. Physiological resistance to S. minor was also identified in a cultivar and a landrace from Indonesia and a rust-resistant line from Queensland. All germplasm found to have high physiological resistance to S. minor belonged to the Spanish type. Inheritance of physiological resistance to S. minor was studied using a Generation Means Analysis (GMA) of the cross TxAG-4/VA 93B and its reciprocal. The broad-sense heritability of physiological resistance on a single plant basis was estimated at 47%, much higher than earlier estimates obtained in field studies. The average gene action of Sclerotinia resistance genes from TxAG-4 was found to be additive. No dominance effects were detected in the GMA. A small but significant reciprocal effect between TxAG-4 and VA 93B indicated that VA 93B passed on some physiological resistance maternally. An experiment was conducted to confirm the value of resistance against both S. minor and S. sclerotiorum. TxAG-4 was found to have physiological resistance to both S. minor and S. sclerotiorum. This resistance was expressed against both Sclerotinia species by progeny that were selected for resistance to S. minor. On the basis of the information obtained, the comparative advantages of 3 strategies for Sclerotinia-resistant cultivar development are discussed: (1) introduction of germplasm; (2) recurrent backcrossing with screening and crossing in the BCnF1 generation; and (3) pedigree selection. At present, introduction and backcrossing are recommended as the preferred strategies.

Analysis of photoperiod sensitivity within a collection of tropical maize populations

We analyzed the variability of a large maize (Zea mays L.) collection of152 tropical populations for photoperiod sensitivity and grain productivityunder long-day conditions to investigate their potential adaptation to temperateconditions. A multilocal experimental design was used: one location withshort-day conditions (Guadeloupe), one location with medium-day conditions (latesowing in the south of France) and two locations with long-day conditions (earlysowing in both the North and South of France). The photoperiod sensitivity wasestimated by the slope of the regression of thermal time from sowing to 50%anthesis on photoperiod. We found highly significant effects of latitude andaltitude of the collecting site of the population on photoperiod sensitivity anda significant but small interaction between these two factors. Populationsoriginated from low altitudes and low latitudes are highly sensitive tophotoperiod, whereas highland populations never display a high photoperiodsensitivity, whatever the latitude of origin. Grain productivity under long-dayconditions was not highly correlated with photoperiod sensitivity. Andeanpopulations were little sensitive to photoperiod and exhibited poor grainproduction under long-day conditions. In contrast, some populations from theCaribbean such as populations from Cuban Flint and Early Caribbean racesexhibited a good grain production although sensitive to photoperiod. The goodadaptation of some Caribbean material to temperate conditions is consistent withthe hypothesis of the successful introduction of Caribbean germplasm in southernregions of the Old World.

Exploiting novel germplasm

Only 0.1% of the world's plant species are grown as crops, and even within these crop species, only a small proportion of the total genetic variability is used in commercial varieties. Here, I address 6 inter-related questions about why it might be desirable to exploit novel germplasm in breeding programs: to exploit plant diversity, to meet continuing breeding objectives in major crops, to develop new crops, to meet new needs from existing crops, to ensure all the world's people benefit from breeding programs, and to ensure the sustainability of crop production. Both species which are rarely cultivated, and genes from accessions and species related to existing crops, can be exploited to meet the need for improvement of agricultural production. Molecular and statistical methods have the potential to speed introduction of novel germplasm—allowing quantitative assessment of diversity, characterisation of desirable genes, tracking of chromosomes, genes, or gene combinations through breeding programs, selection of rare recombination events, and direct gene transfer through transformation. But the challenges of maintaining desirable characters in varieties incorporating novel germplasm, overcoming genetic stability problems, and ensuring safety are considerable.

Molecular typing of Cereus peruvianus clones and their genetic relationships with other Cereus species evaluated by RAPD analysis

SummaryRAPD analysis was used to fingerprint 29 genotypes of Cereus species and examine their genetic diversity. Some modifications were made to the DNA extraction procedure with a view to assuring higher DNA yield and purity. A dissimilarity matrix and dendrogram were constructed to help visualize genetic relationships between different genotypes. The results show that C. peruvianus has only a limited genetic base and that further improvement of this crop may require the introduction of additional germplasm into breeding programmes. RAPD markers were shown to be a valuable tool for clone identification in Cereus species and for detennining genetic relationships.

Performance of selected sweetpotato varieties in Kenya

The major constraints to sweetpotato production in Kenya are use of low yielding albeit well adapted varieties and poor agronomic practices. Utilisation of higher yielding varieties could therefore increase yields. This study was conducted to evaluate introduced germplasm and identify clones with desirable traits. Twenty five clones selected on the basis of high root yield and high dry matter content were evaluated during the 1998 and 1999 long rains seasons. From these, 12 clones were selected for further evaluation in the 2000 long rains. Significant (P = 0.01) genotypic effects were observed for all traits, while genotype x season interactions were significant (P = 0.05) for large and total root yields. Twenty two of the clones had significantly lower foliage yields, compared to the check variety Mafuta. Clones 282-H-12 and WAGA-L-4 consistently recorded dry matter content of over 30%, which is above the critical value of 27%. Mean total root yields were highest in 1999 (14.6 tons ha-1) followed by 1998 (12.0 tons ha-1). The best performing clones were TZ-H-7, 120-H-11, 282-H-12 and TZ-H-10, all producing over 20 tons ha-1 with TZ-H-7 yielding significantly higher than the check variety Naveto. TZ-H-7 also recorded the second highest yield of 13.3 tons ha-1 during 2000. The consistently high number of clones outyielding the check varieties suggests a gain from introduction of new germplasm into the breeding programme in Kenya. Key Words: Dry matter, foliage production, germplasm, sweetpotato breeding (African Crop Science Journal 2001 9(1): 49-58)

An adaptation analysis of Australian and CIMMYT/ICARDA wheat germplasm in Australian production environments

An adaptation analysis was conducted in an attempt to identify adapted germplasm and potential indicator or probe varieties that could be used for more efficient germplasm introduction and evaluation. A set of 39 advanced wheat breeding lines and named varieties from Australian breeding programs and 10 from the CIMMYT/ICARDA programs were tested using 20 environments across the Australian wheatbelt during a period of 3 years. AMMI analysis and classification analysis were performed on grain yield data. Five groups of genotypes with similar patterns in performance within each group were identified, mostly reflecting their origin and pedigree. Most of the genotypes from the CIMMYT/ICARDA programs clustered together as did most of those from the University of Adelaide and Agriculture Western Australia breeding programs. Four groups of environments with similar trends in discriminating genotypes within each group were identified. There was a clear discrimination between subtropical and Mediterranean environments. Subtropical environments with supplementary irrigation showed similar patterns to Mediterranean environments. Basic differences in adaptation and phenotypic stability among genotypes from the CIMMYT/ICARDA programs in relation to genotypes from several breeding programs in Australia were identified. CIMMYT/ICARDA genotypes such as Attila, Nesser, Pfau/Seri//Bow, Genaro 81, and Maya/Nac performed well, especially in subtropical environments. The Australian varieties Hartog and Vulcan showed similar performance and could be used as indicator varieties for assessing introduced germplasm for subtropical regions. University of Adelaide developed genotypes Trident, Spear, Excalibur, and RAC 655, along with the Agriculture Western Australia genotypes Tammin and 82Y:1186, showed wide adaptation to all environments and could be used as indicator varieties for wide adaptation. Similarly, genotypes such as BT Schomburgk, Pelsart, and Sunvale could be used as indicator varieties for the other genotype groups. The results of this study can serve as a basis for identification and introduction of germplasm from the CIMMYT/ICARDA programs for various Australian production environments. It has also provided an understanding of the pattern of discrimination of genotypes across each region of the Australian wheatbelt.

Insect pest problems in tropical agroforestry systems : Contributory factors and strategies for management

Agroforestry trees are attacked by a wide spectrum of insects at all stages of their growth just like other annual and perennial crops. Pest management in agroforestry has not received much attention so far, but recent emphasis on producing high value tree products in agroforestry and using improved germplasm in traditional systems, and emergence of serious pest problems in some promising agroforestry systems have increased awareness on risks posed by pests. Insects may attack one or more species within a system and across systems in the landscape, so pest management strategies should depend on the nature of the insect and magnitude of its damage. Although greater plant diversity in agroforestry is expected to increase beneficial arthropods, diversity by itself may not reduce pests. Introduction of tree germplasm from a narrow genetic base and intensive use of trees may lead to pest outbreaks. In simultaneous agroforestry systems, a number of factors governing tree—crop—environment interactions, such as diversity of plant species, host range of the pests, microclimate, spatial arrangement and tree management modify pest infestations by affecting populations of both herbivores and natural enemies. Trees also affect pest infestations by acting as barriers to movement of insects, masking the odours emitted by other components of the system and sheltering herbivores and natural enemies. In sequential agroforestry systems, it is mostly the soil-borne and diapausing insects that cause and perpetuate damage to the common hosts in tree—crop rotations over seasons or years. An integrated approach combining host-plant resistance to pests, exploiting alternative tree species, measures that prevent pest build up but favour natural enemies and biological control is suggested for managing pests in agroforestry. Species substitution to avoid pests is feasible only if trees are grown for ecological services such as soil conservation and low value products such as fuelwood, but not for trees yielding specific and high value products. For exploiting biological control as a potent, low cost and environmentally safe tool for pest management in agroforestry, research should focus on understanding the influence of ecological and management factors on the dynamics of insect pest-natural enemy populations. Scientists and policy makers in national and international institutions, and donors are urged to pay more attention to pest problems in agroforestry to harness the potential benefits of agroforestry.

COCONUT EMBRYO CULTURE: PRESENT STATUS AND FUTURE THRUST

The safe movement of plant genetic materials has a major concern for many countries in the world. Collecting and exchange of coconut germplasm is difficult and not economic because of the bulkiness of the seed. Moreover, due to short dormancy, the seeds germinate rapidly and thus cannot be stored for more time in a germplasm expedition. Phytosanitary restrictions too severely limit the germplasm introduction. Standardization of embryo culture technique provides an easy and safe alternative for the movement of coconut germplasm and is emphasized in the technical guidelines of FAO/IPGRI (Diekmann, 1997). In vitro culture protocols for coconut zygotic embryos have been established by various coconut research institutes in Cote d’Ivoire, France, India, the Philippines and Sri Lanka (Engelmann, 1998). An embryo culture protocol broadly consisted of at least five components, viz., field collection of embryos, in vitro active storage, in vitro retrieval, ex vitro establishment of plantlets and finally the field establishment. A detailed description of each of these components together with a comparison among different embryo culture protocols developed at various laboratories, applications made for coconut germplasm collection and development required in the future are provided here.

Amplified fragment length polymorphism (AFLP) analysis of genetic variation in Moringa oleifera Lam

Moringa oleifera is an important multipurpose tree introduced to Africa from India at the turn of this century. Despite limited knowledge of the levels of genetic diversity and relatedness of introduced populations, their utilization as a source of seed for planting is widespread. In order to facilitate reasoned scientific decisions on its management and conservation and prepare for a selective breeding programme, genetic analysis of seven populations was performed using amplified fragment length polymorphism (AFLP) markers. The four pairs of AFLP primers (PstI/MseI) generated a total of 236 amplification products of which 157 (66.5%) were polymorphic between or within populations. Analysis of molecular variance (AMOVA) revealed significant differences between regions and populations, even though outcrossing perennial plants are expected to maintain most variation within populations. A phenetic tree illustrating relationships between populations suggested at least two sources of germplasm introductions of Kenya. The high levels of population differentiation detected suggest that provenance source is an important factor in the conservation and exploitation of M. oleifera genetic resources.

Genetic characterization of gooseberry (Ribes grossularia subgenus Grossularia) germplasm using RAPD, ISSR and AFLP markers

SummaryRAPD, ISSR and AFLP markers were used to fingerprint and to examine genetic diversity among twelve genotypes of the gooseberry (Ribes grossularia subgenus Grossularia). AFLP generated unique profiles for each genotype. ISSR could not distinguish three of the genotypes, `Whinham's Industry' `Whitesmith' and `Leveller', whereas RAPD could not distinguish `Whinham's Industry' and `Leveller'. Similarity matrices and dendrograms illustrated the genetic similarities between the different genotypes but some clustering varied, depending on which marker type was being used. The results imply that the European cultivated gooseberry has a narrow genetic base and that further improvement to this crop species may require the introduction of additional germplasm into breeding programmes.

Ploidy reduction in blackberry

Polyploidy in blackberries and ploidy differences between Rubus species are obstacles to the efficient introduction of valuable germplasm, both intra- and interspecific, into blackberry breeding programs. Expansion of the germplasm base would be facilitated by reducing the ploidy level of blackberry cultivars to the diploid level. In this report selection of twin seed, interspecific hybridization, and pollen irradiation were compared as methods in the recovery of dihaploids from tetraploid blackberry cultivars. One dihaploid was obtained through selection of twin seed and several were obtained following interspecific hybridization. The infrequency of twinning and difficulty in detecting twin seed in Rubus reduced the efficiency of this method. The efficiency with which dihaploids could be obtained following interspecific hybridization varied with the pollen parent. Reduced seed set and seed quality following pollinations with respectively R. parvifolius and R. hirsutus could be used to advantage in the recovery of dihaploids from blackberries. Ploidy reduction in several tetraploid blackberry cultivars was obtained following pollinations with 100 and 150 kR gamma irradiated pollen. Most of the seedlings obtained at the 50 kR dosage were aneuploid. Pollen irradiation at 150 kR was the most efficient method of obtaining dihaploids from tetraploid blackberries. Twenty percent of the seedlings obtained following this treatment were dihaploid.

Identification and genetic diversity analysis of date palm (Phoenix dactylifera L.) varieties from Morocco using RAPD markers

Genetic variation among 43 date palm (Phoenix dactylifera L.) accessions, including 37 accessions from Morocco and 6 cultivars from Iraq and Tunisia, was studied using Random Amplified Polymorphic DNA (RAPD) markers. The pre-screening of 123 primers on four genotypes allowed selection of 19 primers which revealed polymorphism and gave reproducible results. All 43 analysed genotypes were distinguishable by their band patterns. RAPD technology therefore appears very effective for identifying accessions of date palm. RAPD-based genetic distance was used to determine the relationships between the accessions. The grouping-association identified by cluster analysis was rather weak. However, morphologically similar varieties clustered together. A relatively low polymorphism and a lack of evident organisation are observed among the date palm varieties grown in Morocco. This could be related to the mode of introduction and maintenance of the Moroccan date palm germplasm involving limited foundation germplasm, exchange of cultivars between plantations, and periodic development of new recombinant cultivars following sexual reproduction.

The herbarium of Paul A. Fryxell (pf) and U.S. Department of Agriculture, College Station, Texas, integrated into The New York Botanical Garden Herbarium (NY)

The herbarium specimens amassed by Paul A. Fryxell while working at the U.S. Department of Agriculture, College Station, Texas, were moved in October 1993 to The New York Botanical Garden and integrated into the Herbarium in 1994. The collection is particularly rich in specimens of the Malvaceae and other families of the Malvales, the areas of Fryxell’s taxonomic specialty. Also included is the cotton reference herbarium of the former Cotton Branch of the Agricultural Research Service, U.S. Department of Agriculture, which consists of voucher specimens of germplasm introductions of cotton (Gossypium) from expeditions and from test plots in the United States and Mexico. A total of 19,918 specimens, including 167 type specimens, have been incorporated into The New York Botanical Garden Herbarium.

Comparison of DNA Marker Technologies in Characterizing Plant Genome Diversity: Variability in Chinese Sorghums

Chinese sorghums [Sorghum bicolor (L.) Moench] are reputed to have a narrow genetic base, resulting from infrequent introduction of exotic germplasm into China. We have used several different molecular approaches to evaluate diversity and relatedness in a selection of 34 Chinese sorghums. The results indicated that different DNA marker technologies for germplasm assessment yield comparable results, but that a relatively new technique termed inter‐simple sequence repeat amplification (ISSR) was relatively rapid, reproducible, and inexpensive. Extensive diversity was observed within the Chinese sorghums, and all lines could be easily differentiated. Different lines collected from the same locality were found to exhibit particularly high levels of relatedness. Contrary to expectations, improved varieties were found to contain more diversity and to be more different from each other than were the Chinese landraces studied, suggesting recent introduction of non‐Chinese germplasm into these improved materials.

A System for Genetic Change in Apomictic Eastern Gamagrass

The ability of a species to undergo genetic change is a necessary component of its adaptive evolution, which can lead to the widening or narrowing of its genetic base. In diplosporous apomictic species, change through sexual or meiotic means is limited or omitted entirely. The objective of this study was to investigate the reproductive attributes of tetraploid apomictic eastern gamagrass, Tripsacum dactyloides var. dactyloides (L.) L. One‐hundred progeny generated from an apomictic tetraploid eastern gamagrass accession were evaluated at a phenotypic, cytogenetic, and molecular level by means of random amplified polymorphic DNA (RAPD) procedures to detect their genetic relatedness to the maternal parent and to each other. Differences in phenotype and RAPD‐PCR (polymerase chain reaction) banding profiles, followed by chromosome counts, revealed the generation of new tetraploid variants. The identification of genetic variation in tetraploid progeny would presumably indicate the production of hybrid individuals generated from the fertilization of a reduced egg cell by a sperm nuclei. However, this study indicates the complete omission of hybrid individuals generated from expected normal sexual behaviors and suggests the observed variation is generated by an incomplete or dysfunctional sexual process. The incidence of this behavior was 4%. The detection and generation of genetically variable but cytologically stable tetraploids, from an apomictic eastern gamagrass, suggests the presence of an additional mechanism whereby this species routinely may undergo genetic change without the introduction of new germplasm.

Processing Foreign Turfgrass Germplasm through Federal Quarantine

Foreign germplasm will continue to be an important component of turfgrass breeding programs. Hundreds of alien pathogens overseas are not found in the USA, and some are responsible for major economically devastating losses. Vegetative propagules, but not imported seeds of turfgrass genera, are quarantined on arrival in the USA. They are closely observed for insects and diseases, and are tested for some 50 viruses reported worldwide to infect grasses. Two virus‐indexing tests are conducted in duplicate under quarantine control 6 to 12 mo apart. They are (i) mechanical transmission of viruses in extracted sap to eight genera of monocots (herbaceous test) such as wheat (Triticum aestivum L.) and corn (Zea mays L.), each of which is sensitive to one or more viruses, and (ii) sap examination under the electron microscope (EM) for the presence of virus particles. More than 95% of the accessions are released from quarantine after completion of 12 to 18 mo of virus testing. Status of quarantined germplasm is maintained in the Germplasm Resources Information Network (GRIN), which any U.S. scientist can access via computer. Processing turfgrass germplasm through quarantine will continue to be an important component of the Federal program of safeguarding exotic germplasm introduction and eventual introgression.

Pedigree analysis of the origin of manganese tolerance in Canadian spring wheat (Triticum aestivum L.) cultivars

Breeding wheat (Triticum aestivum L.) for tolerance to manganese (Mn) might be in some cases more feasible and economical than use of soil amendments. As part of research on the heritability of Mn tolerance, a study on the level of Mn tolerance in Canadian wheat cultivars and its probable origin was accomplished by analysis of cultivar pedigrees and drawing phylogenetic maps to discern filial relationships. Cultivar tolerance to Mn was determined by relative root weight (RRW) in solution culture in the presence of 500 μM Mn. A total of 91 cultivars were screened, 76 of which were Canadian. These data, together with data from another 28 cultivars reported in the literature, were used to draw two pedigree maps, a map for Canadian cultivars only, and a map for the Mn-tolerant Canadian cultivars Norquay and Laura. Results indicated a range of tolerance to Mn among Canadian cultivars. Manganese tolerance, found in either Canadian or foreign germplasm, and of either recent or older selection or origin, seems to have originated from land races from Rio Grande do Sul, the southernmost state of Brazil. Tolerance may have been introduced into Canadian germplasm directly by the use of Brazilian cultivars as parents, or indirectly by the introduction of Mexican germplasm with Brazilian parentages. This information will help the plant breeder to develop plant breeding systems, and may also help in the study of the mechanisms for Mn tolerance in wheat.

COWPEA VIRUSES, INDIGENOUS AND EXOTIC, AND UNIQUE MECHANISMS BY WHICH THEY ARE DISSEMINATED AND INADVERTENTLY INTRODUCED

Vectors with specific vector-virus relationships (e.g., aphid, beetle, thrip, nematode) commonly cause short-range dissemination of cowpea viruses. However, viruses that are seed-borne in cowpea can be disseminated around the world in a single year through seed shipments. Likewise, increased world emphasis on germplasm collection and exchange, for development of improved crop cultivars, increases the risk of disseminating seed-borne viruses in germplasm. Seed-borne cowpea viruses that are not reported in the U.S.A., but are apt to occur in Vigna unguiculata from world centers of cowpea origin include COWPEA APHID-BORNE MOSAIC, COWPEA MILD MOTTLE, COWPEA MOSAIC, and COWPEA MOTTLE VIRUSES. All of these viruses were detected by ELISA serology in V. unguiculata seedlots processed as potential germplasm introductions, in collaboration with the government of Denmark. Germplasm-borne viruses, once introduced into breeding programs, may be seed-transmitted directly into breeding progenies, along with genes derived from the germplasm source. Such viruses also may be spread by insect vectors to other breeding lines, and could cause disease outbreaks to nearby commercial cowpea crops.