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Spinach (Spinacia oleracea L.) is an economically important crop that is cultivated and consumed worldwide. Spinach is interfertile with the wild species S. tetrandra Steven ex M. Bieb. and S. turkestanica Iljin that therefore are presumed to include the most likely crop ancestor. Here we studied variation in 60 Single Nucleotide Polymorphisms (SNP) previously identified in S. oleracea to address the issue of crop ancestry and domestication region. For this purpose we investigated 95 accessions, including 54 spinach landraces from a wide geographic area in Europe and Asia and 16 S. tetrandra and 25 S. turkestanica populations of which the majority had only recently become available. Compared to S. tetrandra substantially higher levels of amplification success and higher levels of variation were detected for S. turkestanica, indicating that S. oleracea is genetically closer to S. turkestanica than to S. tetrandra. Our phylogenetic and population structure analysis supported the conclusion that S. turkestanica is the most likely ancestor of cultivated spinach. In addition, these analyses revealed a group of S. oleracea landraces from Eastern and Southern Asia with a strong genetic resemblance to S. turkestanica. This group includes landraces from Afghanistan and Pakistan, which are part of the native distribution range of S. turkestanica. The domestication of spinach may therefore have occurred more eastwards than generally assumed. Furthermore, our study provides support for the hypothesis that after domestication, spinach was introduced into China via Nepal. Additional collecting of spinach landraces is recommended in order to allow the more precise reconstruction of the crop migration routes. [ABSTRACT FROM AUTHOR]

Spinach (Spinacia oleracea L.) is a highly nutritious leafy vegetable and an economically important food crop. The wild species S. turkestanica Iljin and S. tetrandra Steven ex M. Bieb. are inter-fertile with cultivated spinach and constitute important sources of novel characters to improve spinach varieties, such as for their resistance to pests and diseases. Despite their relevance in plant breeding, S. turkestanica and S. tetrandra are poorly represented in genetic resources collections. Among the reasons for these collection gaps are the difficulties in propagating these species ex situ. Here we report on the results of collecting expeditions for S. turkestanica in Central Asia and for S. tetrandra in the Trans-Caucasus, which were organized by the Dutch gene bank in collaboration with several breeding companies. Furthermore, we also present efficient protocols for the ex situ regeneration of these species. These protocols were used to successfully regenerate 66 S. turkestanica and 36 S. tetrandra samples from the collecting expeditions. These new accessions fill up important collection gaps in ex situ conserved genetic resources of spinach and can be used for exploitation in crop improvement. [ABSTRACT FROM AUTHOR]

This paper addresses the genetic resources, domestication and breeding history of spinach as a comprehensive review of these crop aspects is currently unavailable. It is shown that the availability of genetic resources of wild relatives belonging to the primary gene pool is currently very limited, which hampers breeding and research activities. Therefore, new collecting expeditions are clearly warranted. The domestication of spinach is discussed on the basis of its presumed migration routes and the traits that were probably involved in the domestication syndrome. Spinach is thought to have domesticated in former Persia. Migration then occurred eastwards to China and westwards to Europe, but additional genetic data are needed to reveal the most likely migration routes. Morphological changes in pistillate flowers and loss of dormancy are identified as the main traits involved in the domestication syndrome of spinach. To a large extent we could re-construct the relationships between spinach cultivars that were developed until the 1950s, but this appeared difficult for the more recent cultivars due to intellectual property protection by breeding companies. Resistance against downy mildew has been the main breeding target in spinach. The introgression of NBS-LRR resistance genes from wild relatives is the major strategy to develop downy mildew resistant cultivars. However, the use of loss-of-function alleles of susceptibility genes may provide a more durable strategy to develop resistant cultivars. So far, abiotic resistance and quality traits have received minor attention in spinach research and breeding. This is expected to change considering the potential effects of climate change on these traits. [ABSTRACT FROM AUTHOR]

In recent years, an increasing number of papers has been published on the genetic diversity trends in crop cultivars released in the last century using a variety of molecular techniques. No clear general trends in diversity have emerged from these studies. Meta analytical techniques, using a study weight adapted for use with diversity indices, were applied to analyze these studies. In the meta analysis, 44 published papers were used, addressing diversity trends in released crop varieties in the twentieth century for eight different field crops, wheat being the most represented. The meta analysis demonstrated that overall in the long run no substantial reduction in the regional diversity of crop varieties released by plant breeders has taken place. A significant reduction of 6% in diversity in the 1960s as compared with the diversity in the 1950s was observed. Indications are that after the 1960s and 1970s breeders have been able to again increase the diversity in released varieties. Thus, a gradual narrowing of the genetic base of the varieties released by breeders could not be observed. Separate analyses for wheat and the group of other field crops and separate analyses on the basis of regions all showed similar trends in diversity. [ABSTRACT FROM AUTHOR]

Germplasm conserved as seeds in genebanks requires regular regeneration. In this process, selection and genetic drift may cause loss of genetic diversity from accessions. In the case of selfing crops, separation of distinct lines into different accessions may be an efficient strategy to avoid these negative effects. In order to evaluate the applicability of this method for collection management, knowledge about the level of intra-accession genetic diversity is required. By means of AFLP analysis intra-accession variation was investigated in two cultivars, two landraces and two wild populations of ex situ conserved barley germplasm. In the total sample of 216 individuals analysed (36 per accession), 22 genotypes were observed based on 104 polymorphic loci. The number of genotypes detected ranged from 1 to 3 per accession, except for a Nepalese landrace that revealed 12 genotypes. An UPGMA cluster analysis grouped the genotypes unambiguously into the accession they belonged to and genotypes within accessions were generally found to be closely related. In order to determine the repeatability of the results obtained, 11 individuals belonging to 4 genotypes from the Nepalese landrace were scored for a second set of AFLP markers. Matrices of genetic distances calculated for the two AFLP datasets were found to be highly correlated ( r = 0.9346, P < 0.001). Separation of genotypes into different accessions was considered a relevant option only for the Nepalese landrace. Analysis of molecular variance indicated that this accession could be well divided into 8 distinct lines. Further implications of the results for genebank practices are discussed. [ABSTRACT FROM AUTHOR]

Two approaches to optimise AFLP fingerprinting forthe rapid detection of genetic polymorphisms, i.e.reduced primer selectivity and bulked DNA analysiswere examined. The efficiency of reduced primerselectivity to increase the detection frequency ofgenetic polymorphisms and to obtain more informativefingerprinting profiles was tested in six differentcrops. The number of selective nucleotides was reducedto six in onion, to five in barley, potato, lettuceand cabbage, and to four in flax. This allowed therapid identification of several primer pairs that wereable to discriminate between closely relatedgermplasm. Reproducibility tests on replicate DNAsamples indicated no major negative effects on thereliability of the fingerprinting profiles due to theuse of less selective primers, although for onionpurified DNA was needed to avoid irreproducibleresults. In barley, flax and onion, a less thanfourfold increase in the number of fragments wasobserved when primer pairs were reduced by oneselective nucleotide. This result was attributed todifferent tolerance levels for amplificationmismatches between primer pairs of differentselectivity.The efficiency of bulked DNA analysis to detectgenetic polymorphisms was investigated in differentmixtures of two barley DNA samples. AFLP's of varyingintensity could still be recovered when the two DNA'swere mixed in a 1:1 ratio. However, the frequency ofrecovered bands quickly dropped when in the mixturesthe presence of the DNA carrying the fragments wasdecreased below 50%.The usefulness of the two approaches is discussed inrelation to various aspects of genetic resourcesmanagement. [ABSTRACT FROM AUTHOR]

Presents research which described polygynous oystercatcher trios and the reproductive consequences of such polygyny. Mating systems in waders; Varying behaviors in breeding units; Study of Haematopus ostralegus, which is usually monogamous; Classical form of polygyny and a variant.

Introduction: Lettuce (Lactuca sativa L.) is generally not specifically acknowledged for its taste and nutritional value, while its cultivation suffers from limited resistance against several pests and diseases. Such key traits are known to be largely dependent on the ability of varieties to produce specific phytochemicals.Objectives: We aimed to identify promising genetic resources for the improvement of phytochemical composition of lettuce varieties.Methods: Phytochemical variation was investigated using 150 Lactuca genebank accessions, comprising a core set of the lettuce gene pool, and resulting data were related to available phenotypic information.Results: A hierarchical cluster analysis of the variation in relative abundance of 2026 phytochemicals, revealed by untargeted metabolic profiling, strongly resembled the known lettuce gene pool structure, indicating that the observed variation was to a large extent genetically determined. Many phytochemicals appeared species-specific, of which several are generally related to traits that are associated with plant health or nutritional value. For a large number of phytochemicals the relative abundance was either positively or negatively correlated with available phenotypic data on resistances against pests and diseases, indicating their potential role in plant resistance. Particularly the more primitive lettuces and the closely related wild relatives showed high levels of (poly)phenols and vitamin C, thus representing potential genetic resources for improving nutritional traits in modern crop types.Conclusion: Our large-scale analysis of phytochemical variation is unprecedented in lettuce and demonstrated the ample availability of suitable genetic resources for the development of improved lettuce varieties with higher nutritional quality and more sustainable production. [ABSTRACT FROM AUTHOR]