1,721,234 research outputs found
Asymmetric Gene flow and differential geographical structure of molecular diversity in wild and domesticated common bean (Phaseolus vulgaris L.) from Mesoamerica
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Varietal differences in sodium uptake in barley cultivars exposed to soil salinity or salr spray
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Tolleranza a stress salini in germoplasma sardo di orzo (Hordeum vulgareL.)
Full text linkSardinia is one of the Italian regions were the salty soil is most frequently found. Soil borne salinity often occurs together
with air bome salinity due to the effects of the salty wind. In Sinis, a peninsula located in Centrai Western Sardinia, both types of
salinity stress are present. In this area barley is widely cultivated and many farmers generally prefer to grow local populations
which are well adapted to local environmental conditions. The aim of the research was to characterize the responses to both types
of salinity stress (via root and via leaf) of two genotypes («Sinis 0/27» and «Sinis 0/28») extracted from a local Sinis population of
six-row barley, and compare them with two varieties, «California Mariout 67» and «Sunbar 400», well known to be salt tolerant
to soil borne salinity. The results showed that in barley differences in the effects of salt absorbed via the rootvsfoliar uptake exist,
togheter with genetic diversity for air borne salinity tolerance which is usually found only in coastal and cliff species. In particular
the Sinis genotypes appeared to be tolerant to salty spray due to their specific adaptation. According to these results, the use of
adapted germplasm seems to be worthwhile in breeding programs which are aimed at the synthesis of varieties suitable for areas
were salinity stresses frequently occur.La Sardegna è una fra le regioni italiane in cui la presenza di terreni salsi è più frequente. A questa forma di stress salino si
accompagna spesso l'azione dei venti che trasportano acqua marina in sospensione inducendo uno stress salino per via
fogliare. Nel Sinis, una penisola della Sardegna centro-occidentale, entrambe le forme di stress salino sono presenti. Qui l'orzo
(Hordeum vulgareL.) è molto coltivato e generalmente sono utilizzate delle popolazioni locali adattate alle condizioni
pedoclimatiche della zona. Scopo del presente lavoro è lo studio della risposta a entrambe le forme di stress salino, per via
radicale e per via fogliare, in due genotipi («Sinis 0/27» e «Sinis 0/28») estratti da una popolazione di orzo polistico collezionata
nella penisola del Sinis a confronto con due varietà note per la loro tolleranza alla salinità del terreno, «California Mariout 67»
e «Sunbar 400». I risultati ottenuti indicano la possibilità, per quanto riguarda l'orzo, di distinguere fra una tolleranza allo
stress salino dovuto all'assunzione di sale per via radicale e una tolleranza allo stress salino causato dall'assorbimento di sale
per via fogliare che fino a oggi è stata riscontrata solamente in specie di non elevato interesse agronomico che tendono
a colonizzare gli ambienti costieri. I due genotipi del Sinis valutati, in particolare «Sinis 0/27», sono risultati dotati di una
buona capacità di tollerare lo stress salino applicato per via fogliare grazie al loro specifico adattamento. Ciò indica
l'importanza dell'utilizzazione di germoplasma adattato nel miglioramento genetico per ambienti caratterizzati dalla presenza
di stress salini
Possible 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
Genetic structure of the Anthyllis vulneraria L. s.l. species complex in Estonia based on AFLPs
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Going 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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