1,721,099 research outputs found
Asymmetric Gene flow and differential geographical structure of molecular diversity in wild and domesticated common bean (Phaseolus vulgaris L.) from Mesoamerica
No full textPossible effects of (trans)gene flow from crops on the genetic diversity from landraces and wild relatives
No full textGene flow is a potential concern associated with the use of transgenic crops because
it could affect genetic diversity of related landraces and wild relatives. This concern has
taken on added importance with the looming introduction of transgenic crops in centers
of crop domestication (Mexico, China) and those producing pharmaceutical compounds.
For gene flow to take place among cultivars and their wild relatives, several steps
have to be fulfilled, including the presence of cultivars or wild relatives within pollen
or seed dispersal range, the ability to produce viable and fertile hybrids, at least
partial overlap in flowering time, actual gene flow by pollen or seed, and the establishment
of crop genes in the domesticated or wild recipient populations. In contrast with
domestication genes, which often make crops less adapted to natural ecosystems, transgenes
frequently represent gains of function, which might release wild relatives from constraints
that limit their fitness. In most sexually reproducing organisms, the chromosomal region
affected by selection of a single gene amounts to a small percentage of the total
genome size. Because of gene flow, the level of genetic diversity present in the
domesticated gene pool becomes a crucial factor affecting the genetic diversity of the
wild gene pool. For some crops, such as cotton and maize, the introduction of transgenic
technologies has led to a consolidation of the seed industry and a reduction in the
diversity of the elite crop gene pool. Thus, diversity in improved varieties grown by
farmers needs to be monitored. Several areas deserve further study, such as the actual
magnitude of gene flow and its determinants in different agroecosystems, the long-term
effects of gene flow on genetic diversity both across gene pools and within genomes,
the expression of transgenes in new genetic backgrounds, and the effects of socio-economic
factors on genetic diversity
Assessment of Inter Simple Sequence Repeat Markers to Differentiate Sympatric Wild and Domesticated Populations of Common Bean (Phaseolus vulgaris L.)
No full textThe genetic identity of a patented yellow bean
No full textSince a 1980 Supreme Court decision, it is possible in the USA to obtain a utility patent for crop cultivars and other life forms. Furthermore, it is also possible to obtain Plant Variety Protection (PVP) for a cultivar. Among the awards of the United States Patent and Trademark Office and the USDA Plant PVP Office are a utility patent and a PVP certificate, respectively, associated with a yellow-seeded bean (Phaseolus vulgaris L.), specifically the cultivar Enola. These awards have been controversial because of, among several reasons, the perceived lack of novelty of the yellow seed color and the cultivar itself. To check the origin of Enola, we fingerprinted a representative sample of 56 domesticated common bean accessions, including a subsample of 24 cultivars with yellow seeds similar to those of Enola. Fingerprinting was accomplished with amplified fragment length polymorphisms (AFLP). Five EcoRI/MseI and five PstI/MseI primer combinations were used, which revealed 133 fragments. The PstI/MseI primer combinations revealed a 3-fold larger number of polymorphic markers than the EcoRI/MseI primer combinations. Most yellow-seeded beans, including Enola, were included in a tightly knit subgroup of the Andean gene pool. Enola was most closely related to the pre-existing Mexican cultivar Azufrado Peruano 87. A sample of 16 individuals of Enola displayed a single 133 AFLP- fragment fingerprint, which was identical to a fingerprint observed among yellow-seeded beans from Mexico, including Azufrado Peruano 87. Probability calculations of matching the specific Enola finger- print showed that the most likely origin of Enola is by direct selection within pre-existing yellow-bean cultivars from Mexico, most probably ‘Azufrado Peruano 87’
AFLP analysis of the phenetic organization and genetic diversity of Vigna unguiculata L. Walp. reveals extensive gene flow between wild and domesticated types
No full text
Tagging the signatures of domestication in common bean (Phaseolus vulgaris L.) by means of pooled DNA samples
No full textBackground and Aims The main aim of this study was to use an amplified fragment length polymorphism (AFLP)-based, large-scale screening of the whole genome of Phaseolus vulgaris to determine the effects of selection on the structure of the genetic diversity in wild and domesticated populations.
Methods Using pooled DNA samples, seven each of wild and domesticated populations of P. vulgaris were studied using 2506 AFLP markers (on average, one every 250 kb). About 10 % of the markers were also analysed on individual genotypes and were used to infer allelic frequencies empirically from bulk data. In both data sets, tests were made to determine the departure from neutral expectation for each marker using an FST-based method.
Key Results The most important outcome is that a large fraction of the genome of the common bean (16 %; P < 0·01) appears to have been subjected to effects of selection during domestication. Markers obtained in individual genotypes were also mapped and classified according to their proximities to known genes and quantitative trait loci (QTLs) of the domestication syndrome. Most of the markers that were found to be potentially under the effects of selection were located in the proximity of previously mapped genes and QTLs related to the domestication syndrome.
Conclusions Overall, the results indicate that in P. vulgaris a large portion of the genome appears to have been subjected to the effects of selection, probably because of linkage to the loci selected during domestication. As most of the markers that are under the effects of selection are linked to known loci related to the domestication syndrome, it is concluded that population genomics approaches are very efficient in detecting QTLs. A method based on bulk DNA samples is presented that is effective in pre-screening for a large number of markers to determine selection signatures
Identification And Molecular Diversity Of A Genomic Sequence Similar To Shatterproof (Shp1) In Phaseolus vulgaris L.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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