Genetic structure of Lima bean (<Emphasis Type="Italic">Phaseolus lunatus</Emphasis> L.) landraces grown in the Mayan area

Lima bean (Phaseolus lunatus L.) is an important crop in the Mayan culture. The Mayan area, considered as a main center of Mesoamerican diversity, has been divided into two subareas: the Mayan lowlands and the Mayan highlands. The Yucatan Peninsula is part of the Mayan lowlands and holds the highest number of Lima bean landraces of Mexico, but Lima beans are in high risk of genetic erosion due to intensification of the traditional Mayan agriculture. However, information on genetic diversity of Lima beans of the Mayan highlands is lacking. By using 46 landraces collected in the Mayan area (23 from each subarea) and 73 ISSR loci (inter-simple sequence repeats), we analyzed the structure, diversity and genetic relationships of Lima beans of this part of Mesoamerica. High levels of diversity (H _BAY = 0.45) and genetic structure (F _ST = 0.66) were found for the whole Mayan area. Genetic diversity in the Mayan lowlands was apparently higher than the Mayan highlands (H _BAY = 0.44 and 0.36, respectively); but differences were not statistically significant. Genetic structure between the subareas was high (AMOVA = 30% of total variation), most landraces grouping according to their geographic origin. This study shows the importance of the Mayan culture in the diversification and conservation of Lima beans. The results provide important information that should be considered when implementing strategies to collect Lima bean landraces and planning in situ and ex situ programs to conserve these landraces in the Mayan region.     

Morphological Variation of Fruit in Mexican Populations of <Emphasis>Cocos nucifera</Emphasis> L. (Arecaceae) under <Emphasis Type="Italic">in situ</Emphasis> and <Emphasis Type="Italic">ex situ</Emphasis> Conditions

Morphological variation of the coconut fruit measured in situ has been used to estimate genetic diversity, and generate hypotheses about the evolutionary and geographical diffusion of coconut. Some authors have questioned the validity of this methodology due to the possibly high effect of the environment on the morphological characteristics of the fruit. The general aim of this study is to validate this methodology through: (1) characterizing the pattern of morphological variation of the fruit under homogeneous growing conditions ex situ; (2) comparing this pattern with those already reported in situ; (3) estimating the heritability values for the components of fruit in coconut. Results are also discussed in comparison with ex situ leaf variation and biochemical and molecular variation patterns previously studied. Principal components and discriminant analyses indicated that the characters that best differentiate groups are basically the same in situ and ex situ. Grouping patterns obtained with principal components and cluster analysis were similar for both growing conditions. They were also similar to the grouping pattern obtained with ex situ leaf characters. No significant differences were found in the variation coefficients of fruit characters between the same populations in situ and ex situ. Consistency was found between patterns of morphological variation of fruit ex situ and in situ, and those obtained using iso-enzymatic and molecular characteristics. The results are also consistent with hypotheses on the origin and diffusion of the germplasm introduced to Mexico. High values of heritability were found in nine characters. Weight and water percentage showed the highest values (0.88 and 0.883), with a strong correlation to the mass and the roundness of fruit and seed, suggesting that human selection of these characteristics led to the differentiation of domesticated populations. We conclude that morphological characterization of the coconut fruit in situ is useful to estimate its genetic variability because of its simplicity, speed and ease of application in the field and in remote areas.     

Morphological characterization of snake melon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">flexuosus</Emphasis>) populations from Palestine

Genetic diversity in 50 snake melon accessions collected from Palestine (West Bank) was assessed by examining variation in 17 phenotypic characters. These accessions belonged to four important landraces of Cucumis melo var. flexuosus: Green “Baladi” (GB), white Baladi (WB), green Sahouri (GS), and white Sahouri (WS). Principal component analysis (PCA) and a dendrogram were performed to determine relationships among populations and to obtain information on the usefulness of those characters for the definition of cultivars. PCA revealed that secondary fruit skin color, flesh color, primary fruit skin color, and secondary skin color pattern were the principal characters to discriminate melon accessions examined in the present study. According to the scatter diagram and dendrogram, landraces of C. melo var. flexuosus: GB, WB, GS, and WS formed different clusters. However, based on Euclidean genetic coefficient distances, GB and WB had the least degree of relatedness with GS and WS, indicating distantly related landraces (Baladi and Sahouri). On the other hand, the highest degree of relatedness was detected between WS on one hand, and both GS and WB on the other indicating closely related cultivars. Fruit traits variability among the different snake melon landraces was evaluated and discussed in this study. This evaluation of fruit trait variability can assist geneticists and breeders to identify populations with desirable characteristics for inclusion in cultivars breeding programs.     

Morphological patterns in a world collection of <Emphasis Type="Italic">Cleome gynandra</Emphasis>

Cleome gynandra L. is a leafy vegetable native to sub-Saharan Africa and Asia and cultivated on dry areas. The plant plays an important role in the food and nutrition security of local communities. The objective of this study was to illustrate variation and diversity in the Cleome collection held at the World Vegetable Center. In total, 242 accessions were cultivated and morphologically characterized and analyzed. The gynophore and filament, both important organs of the flower, played a key role in taxonomical identification. High morphological variation was detected in traits including plant height, pod length, leaf size, flower color, and earliness. Distinct morphological differentiation was detected between Asian and African accessions. On average, the African accessions were larger, less uniform and later in flowering and seed maturation than the Asian accessions. The results were used to establish a core collection of 49 Cleome accessions. Gaps in the current collection were detected. High within-accessions diversity challenges the existing ex situ conservation system; to maintain diversity, seed should be collected from a large number of plants, both during the collection mission and in ex situ regeneration. The results are relevant for germplasm collection strategies and regeneration protocols for good genebank practices.     

Population clonal diversity and fine-scale genetic structure in <Emphasis Type="Italic">Oryza officinalis</Emphasis> (Poaceae) from China,implications for <Emphasis Type="Italic">in situ</Emphasis> conservation

Population clonal diversity and fine-scale genetic structure of Oryza officinalis Wall. ex Watt, an endangered species in China recently experiencing habitat degradation, was estimated using inter simple sequence repeat markers. We analyzed the genetic variations of 440 samples exhaustively collected from nine O. officinalis populations. Relatively rich clonal diversity and poor genetic variation were found in the extant populations. We found that the number of genets, the percentage of polymorphic loci, and gene diversity decreased with population decline, suggesting that habitat degradation will lead to further genetic depletion of O. officinalis populations. A pronounced spatial genetic structure occurs at both the ramet and genet levels in several larger populations, which is the result of clonal growth and concomitant inbreeding. The in situ conserved population PS holds much more genotypes than other populations with the similar population size, which might have more seedling recruitments from the soil seed bank due to habitat disturbance, suggesting a moderate disturbance combined with habitat degradation-avoiding measures are effective for in situ conservation of this species.     

Morphological diversity of panicle traits in Kam fragrant glutinous rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>)

Panicle traits are the most intuitive and representative features of rice germplasm resources that have been utilized in the determination of its identity, genetic diversity, yield, and quality. Based on the approaches of ethnobotany, cultural anthropology and plant morphology, we analyzed the panicle traits of 95 traditional Kam fragrant glutinous rice landraces according to folk classification in Qiandongnan Prefecture of Guizhou Province in the past 10 years. A total of 95 Kam fragrant glutinous rice landraces were tested, of which 91% consisted of those with awns, and landraces with awn lengths of 2–6 cm comprised 62%. The coefficient of variation (CV) of awn color, husk color and Grain color was more than 50%, thereby indicating extensive morphological variations among the traditional Kam fragrant glutinous rice landraces. The average Shannon–Wiener value (diversity index, H′) for panicle qualitative traits was 0.50, which was significantly higher than that of quantitative traits (0.22), thereby indicating a relatively higher degree of genetic diversity among qualitative traits. Cluster analysis of panicle morphological traits showed that 95 Kam fragrant glutinous rice landraces could be divided into five categories, using the Euclidean distance of 0.68 as threshold. Each cultivar manifested unique panicle traits. The present study on the morphological diversity of Kam fragrant glutinous rice landraces provided basic information that may be utilized for the conservation and sustainable use of Kam fragrant glutinous rice landraces.     

Assessment of genetic variation in common bean (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.) from Nebrodi mountains (Sicily,Italy)

This study was carried out to estimate the level of diversity existing within some common bean landraces still cultivated in Nebrodi mountains, North-western area of Sicily. The multidisciplinary approach adopted to reach this goal involved the characterisation of collected material through morphological, biochemical and molecular marker analyses. The nutritional quality of seeds was also investigated in view of the proposition of the best landraces as niche products. Results showed that those bean landraces retain a considerable level of heterogeneity. The use of both biochemical and molecular markers showed that all landraces clustered into two main groups, corresponding to the Andean and Mesoamerican gene pools. Our results suggest that the best strategy for preserving the diversity of common bean from a restricted area such as Nebrodi mountains, necessitates of a deep knowledge of germplasm to avoid the loss of precious genetic resources or, on the contrary, the safeguard of populations genetically redundant.     

Nutritional composition and cooking characteristics of tepary bean (<Emphasis Type="Italic">Phaseolus acutifolius</Emphasis> Gray) in comparison with common bean (<Emphasis Type="Italic">Phaseolus vulgaris</Emphasis> L.)

Tepary bean is a highly abiotic stress tolerant orphan crop for which there has been limited research on its nutritional value and cooking characteristics. These are key aspects when considering the potential for broader adoption of tepary bean. Therefore, the goal of this study was to evaluate a large set of seed composition and cooking traits related to human nutrition using both landraces and breeding lines of domesticated tepary bean from replicated field trials and to compare the traits in tepary with those in common bean. Tepary bean showed reduced fat and ash concentration and higher sucrose concentration as compared to common bean. Of the twelve amino acids evaluated, only proline in one of the two trials was statistically different between the two species. There were statistically significant differences between tepary and common bean for the concentration of some elements in this study; however, the elemental concentrations fell within the range of those found for common bean in previous studies. The majority of tepary bean lines showed consistently short cooking times and a high percentage of seeds showed measurable water uptake, while some showed a hardshell trait (low water uptake) and longer cooking times. Principal component analysis on a subset of traits showed a distinct group of common beans and two tepary bean groups that were divided on the basis of several agronomic, cooking, and elemental composition traits. Tepary bean, as with other pulses, is a highly nutritious crop with the range of composition and cooking characteristics similar to those of common bean. The variability for seed composition and cooking traits found within tepary bean can be exploited for its improvement.     

AFLP analysis of genetic diversity in leafy kale (<Emphasis Type="Italic">Brassica oleracea</Emphasis> L. convar. <Emphasis Type="Italic">acephala</Emphasis> (DC.) Alef.) landraces,cultivars and wild populations in Europe

AFLP markers were used to characterize diversity and asses the genetic structure among 17 accessions of kale landraces, cultivars and wild populations from Europe. The range of average gene diversity in accessions was 0.11–0.27. Several landraces showed higher levels of diversity than the wild populations and one cultivar had the lowest diversity measures. The landraces that were most genetically diverse were from areas where kales are known to be extensively grown, suggesting in situ conservation in these areas as a supplement to storage of seeds in gene banks. An analysis of molecular variance (AMOVA) showed that 62% of the total variation was found within accessions. For most accessions, genetic distance was not related to geographic distance. Similarities among accessions were probably not caused by recent gene flow since they were widely separated geographically; more likely the relationship among them is due to seed dispersal through human interactions. Our results indicate that a kale population found in a natural habitat in Denmark was probably not truly wild but most likely an escape from a cultivated Danish kale that had subsequently become naturalized.     

Genetic diversity of barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) landraces from the central highlands of Ethiopia: comparison between the <Emphasis Type="Italic">Belg</Emphasis> and <Emphasis Type="Italic">Meher</Emphasis> growing seasons using morphological traits

In Ethiopia, barley is generally grown in two different planting seasons per year: during the long rainy season (Meher) and the short rainy season (Belg). The aim of the present study was to assess for the first time the role of this ‘two-season system’ on the structure of the genetic diversity of the Ethiopian barley landraces. We characterised 3,170 individual genotypes from 106 landrace populations using eight morphological spike traits. The diversity within population was higher in the season where barley is more important (Belg), and in general, where its cultivation is in larger plots because of weaker ‘competition’ with others crops. This indicates that barley diversity has a complex relationship with variations in the surrounding agro-ecosystem. Overall, the divergence between the two seasons was quite small (3.4%), suggesting that seed flow does not occur independently across the years within the two seasons. This would affect the amount of mutations and historic recombination that have accumulated within these populations.     

Agronomic and genetic characterization of wild emmer wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> subsp<Emphasis Type="Italic">. dicoccoides</Emphasis>) introgression lines in a bread wheat genetic background

During a long evolutionary history across a range of environmental conditions in the Near East Fertile Crescent, wild emmer wheat (Triticum turgidum subsp. dicoccoides) has accumulated a wealth of genetic diversity and adaptations to multiple biotic and abiotic stress conditions. The joint effects of the domestication and subsequent selection in man-made agro-ecosystems have considerably reduced the genetic variation in cultivated crop species as compared to their wild progenitors. The wild emmer gene pool harbors a rich allelic repertoire for improving numerous agronomically important traits. A set of advanced wild emmer wheat introgression lines (ILs) was previously established on a bread wheat genetic background. It combines genetic diversity from the wild progenitor as well as the genetic background of the cultigen. Based on field evaluations, the set of ILs (divided hierarchically into different families based on the genetic background) has exhibited high phenotypic variance in agronomically important traits. Analyses of variance ?(ANOVA) have shown that the effect of the hierarchical genetic factors was significant in the vast majority of the traits. Similarly, characterizations by molecular markers of known traits have shown that the genetic profile differs between ILs from different genetic backgrounds. Multivariate principal component analysis has revealed interesting associations between vegetative and reproductive traits and illustrated the impact of some of these traits on ILs distribution in the PC1 and PC2. The exploitation of the wild emmer wheat ILs as a tool for reintroduction of alleles that were lost during domestication and possible implications for wheat breeding are discussed.     

Diversity in cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.) local populations from Greece

Cowpea cultivation in many countries around the Mediterranean Basin depends on a number of locally adapted populations conserved on-farm at a small scale, rather than on the use of modern varieties. Documentation, characterization and exploitation of traditional local populations could contribute to their conservation and utilization as sources of desirable characteristics. Therefore, a study was conducted to (a) characterize, (b) assess diversity and (c) classify 23 on-farm conserved local cowpea populations based on 32 agro-morphological traits. Investigations on diversity of characteristics related to seed yield, mineral and seed crude protein content as well as on correlations among them were carried out. A relatively high phenotypic diversity was observed. In particular, a high level of within population diversity was found (\( \bar{H}s \) = 0.34) exceeding that among populations’ diversity (Gst = 0.27). Principal component analysis classified the majority of local populations into two groups (mainly according to populations’ seed coat color and eye color), further divided into six subgroups regardless of the populations’ geographical origin. Significant differences were also observed among the populations studied for potassium and calcium, as well as for their seed crude protein content which ranged from 22.14 to 28.37 %. The results show appreciable levels of intra- and inter-phenotypic diversity in on-farm conserved cowpea populations, which indicates the existence of a valuable gene pool for future exploitation in breeding programs.     

Genetic structure and history of Swiss maize (<Emphasis Type="Italic">Zea mays</Emphasis> L. ssp. <Emphasis Type="Italic">mays</Emphasis>) landraces

Between 1930 and 2003 with emphasis on the 1940s maize landraces (Zea mays L. ssp. mays) from all over Switzerland were collected for maintenance and further use in a new Swiss breeding program. The genetic relationship and diversity among these accessions stored in the Swiss gene bank is largely unknown. Our hypothesis was that due to the unique geographic, climatic, and cultural diversity in Switzerland a diverse population of maize landraces had developed over the past three centuries. The aims were to characterize the genetic diversity of the Swiss landraces and their genetic relationship with accessions from neighbouring regions as well as reviewing their history, collection, and maintenance. The characterization and grouping was based on analyses with ten microsatellite markers. Geographic, cultural, and climatic conditions explained a division in two distinct groups of accessions. One group consisted of landraces collected in the southern parts of Switzerland. This group was related to the Italian Orange Flints. The other group contained accessions from northern Switzerland which were related to Northern European Flints in particular German Flints. Historic evidence was found for a frequent exchange of landraces within the country resulting in a lack of region-specific or landrace-specific genetic groups. The relatively large separation between the accessions, indicated by high F _ST (0.42), might be explained partly by a bottleneck during the collection and maintenance phase as well as by geographical and cultural separation of north and south of the country. Due to the high genetic diversity, the accessions here are a potential resource for broadening the European flint pool.     

AFLP analysis of genetic diversity in five accessions of Polish runner bean (<Emphasis Type="Italic">Phaseolus coccineus</Emphasis> L.)

Runner bean (Phaseolus coccineus L.) is traditionally cultivated in Poland for dry seeds. The national collection of runner bean maintained in the National Center for Plant Genetic Resources gathers 152 accessions, which are mainly landraces originated in Poland (68%), Ukraine (17%) and Slovakia (10%). The collection contains valuable genetic resources for bean breeders and research. The aim of this study was to describe the level and structure of genetic diversity of three landraces and two commercial cultivars of runner bean from the national collection in order to assess their genetic potential for breeding. Amplified Fragment Length Polymorphism analysis included five combinations of selective primers. Analysis of seven genetic diversity parameters reveled fair amount of genetic variation both in landraces and cultivars. High genetic diversity of commercial cultivars relative those of landraces suggests that the breeding process leading to their release was rather moderate and most likely included domestic gene pool of runner bean. Low gene diversity and low Nei’s genetic distance values as well as intergradations among accessions in the PCoA may indicate reduced variability P. coccineus grown in Poland as a result of its migration pathways.     

Collecting maize (<Emphasis Type="Italic">Zea mays</Emphasis> L. convar. <Emphasis Type="Italic">mays</Emphasis>) with potential technological ability for bread making in Portugal

The Portuguese maize bread (“broa”) manufactured from traditional maize landraces still plays an important economic and social role on Central and Northern rural communities of the country. However the traditional maize landraces agricultural systems are changing. Local maize landraces are in risk of disappearing because of the progressive adoption of hybrid varieties not suitable for bread production. These changes are contributing to a major loss of genetic diversity. An expedition took place in the Central region of Portugal (Beira Interior and Beira Litoral) with the purpose of collecting enduring maize landraces with technological ability for bread production and to access the possibility of establishing a participatory plant breeding and conservation program. A total of 51 different maize landraces and 175 other varieties of associated crops were collected. Maize landraces showed to maintain high diversity and potential for improvement. The production relayed on small farms with polycrop, quality oriented, sustainable systems. A participatory plant breeding and conservation program would be possible on this region with the proviso that local authorities would be involved. This program would allow a higher valuation of these maize populations, contributing to halt the current loss of these unique Portuguese maize landraces.