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1.
P. Nilsson Sven‐Åke Johansson Arnulf Merker 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):159-164
The seed oil composition and content in a number of accessions from species of the genera Barbarea and Lepidium were analysed. The oil from most accessions of B. verna contained more than 50% erucic acid, while the oil from B. vulgaris contained ～ 30% erucic acid, and 22% each of oleic and linoleic acid. The oil from B. intermedia resembled that of B. verna. The oil content was ～ 30% in all three species. The oil composition of L. campestre and L. heterophyllum is ～ 35% linolenic acid and 23% erucic acid. Other Lepidium species had up to 47% linolenic acid in the oil. The oil content of L. campestre and L. heterophylhim was just below 20%, but other species had more than 30% oil in their seeds. The variation in oil composition found within and between species is considered sufficient for the breeding of valuable oil qualities in both genera. 相似文献
2.
Arnulf Soleng Antonio B.S. Polo Tor A. Bakke 《Aquaculture (Amsterdam, Netherlands)》2005,250(3-4):616-620
Both laboratory and field experiments have demonstrated that aqueous aluminium can act as a paraciticide to the monogenean Gyrodactylus salaris Malmberg, 1957 infecting freshwater salmonids. However, the reproductive conditions of gyrodactylids surviving to cessation of an aluminium exposure is unknown. Therefore, Atlantic salmon (Salmo salar L.) parr infected with G. salaris was experimentally exposed to elevated concentrations of aqueous aluminium for more than 1 month. During this period, the infection increased the first week before it peaked and started to steadily decline approaching elimination. When almost all parasite specimens were eliminated, the water quality was adjusted to normal aluminium-poor freshwater. During the next 3 weeks, the surviving G. salaris were shown to clearly resume their reproduction. The experiment demonstrates the potential of the gyrodactylids to reproduce after cessation of an aluminium exposure. Thus, the as-yet unknown mechanism behind the toxic effects of aluminium on G. salaris survival and reproduction might to some extent be reversible. The present study gives further support for this metal as a parasiticide to G. salaris but demonstrates at the same time that in order to eliminate the parasites totally, the aluminium treatment must eradicate all G. salaris from the skin of the infected hosts. Furthermore, the potential development of resistance to aluminium should also be studied. 相似文献
3.
Carlos Henry Loáisiga Agnese Kolodinska Brantestam Oscar Diaz Björn Salomon Arnulf Merker 《Genetic Resources and Crop Evolution》2011,58(7):1021-1028
Teosintes are the closest relatives to modern maize, Zea mays L. ssp. mays. They are wild grasses with a native distribution area from Mexico to Nicaragua and represent an important genetic resource.
However, the genetic diversity of Nicaraguan teosinte (Zea nicaraguensis Iltis et Benz) has not yet been determined. This teosinte species has decreased in the last 25 years and now must be regarded
as an endangered species. An analysis of the genetic diversity of Zea nicaraguensis was carried out in a total of 240 individuals from seven populations. Eleven Simple Sequences Repeat (SSR) primer pairs were
used. A total of 42 alleles were found, the range of alleles per locus was 2–5 (mean 3.8) and the numbers of genotypes varied
between primers. The primer Bnlg 1538 showed the highest value, with 45 genotypes through all populations. The genetic diversity observed (Ho) between all
populations varied from 0.51 to 0.63, with an average of 0.563. One of the populations had as many as 40 alleles. Analysis
of molecular variance (AMOVA) revealed that most of the variation was within population, at a significantly high level (P < 0.001). Rare alleles were detected in all populations, but unique alleles were only found in four populations. These results
are highly relevant when developing conservation strategies and show that preserving populations in their natural habits is
highly important. 相似文献
4.
5.
A total of 4,840 entries of tetraploid wheat germplasm collections representing 121 accessions from Ethiopia were evaluated
for phenologic and qualitative trait diversity. The objectives were to assess the diversity patterns of the germplasm with
respect to regions, species and altitudinal class. High values of Shannon–Weaver Diversity Index (H′) were recorded for most
traits in each region, altitudinal classes, and species. Monomorphism was also high at accession levels. Both H′ and Nei’s
gene diversity value for the entire data set (total gene diversity H
T = 0.572; the within accessions gene diversity H
S = 0.112; and gene diversity among accessions D
ST = 0.460) showed the variation for the trait is mainly among accessions/populations rather than within accessions/population.
The least mean H′ value over all the traits used for the study was obtained from released varieties (among the origin groups)
and Triticum
dicoccon (among species). Triticum
durum exhibit the highest H′ for a number of traits. Accessions collected from altitudinal class III (2401–2800 m a.s.l.) and class
II (2001–2400 m a.s.l.) showed the highest H′ values for a valuable number of traits. Thus classifications using various phenology
and qualitative traits enable to identify adaptation of a genotype and would improve the evaluation of genotype for potential
adaptation. 相似文献
6.
Carlos Henry Loáisiga Oscar Rocha Agnese Kolodinska Brantestam Björn Salomon Arnulf Merker 《Genetic Resources and Crop Evolution》2012,59(1):95-111
The genus Zea (teosinte) has a native distribution from Mexico to Nicaragua (Meso-America region) and studies on teosinte species may help
improve our understanding of maize genetics, population genetics, genome evolution and crop evolution. Moreover, since F1
hybrids between teosinte and maize are fertile, all teosinte species can potentially contribute to maize breeding in the form
of traits such as resistance or tolerance to heavy metals in the soil and other adverse environmental conditions. Gene flow
between maize and teosinte occurs in Mexico and Central America. This study analysed the genetic diversity of teosintes by
using the microsatellite technique on a total of 120 individuals from six different species and 21 Simple Sequence Repeats
(SSR). A total of 109 alleles were found and the number of alleles per locus ranged from 2 to 7. The genetic diversity varied
between all species from 0.514 to 0.572, with a mean value of 0.548 (Nei index). Rare and unique alleles were detected in
all species, with the highest frequencies found in Zea diploperennis Iltis, Doebley et Guzman, Zea perennis (Hitchc.) Reeves et Mangelsdorf and Zea nicaraguensis Iltis et Benz, which had more than seven rare alleles each. Analysis of molecular variance revealed that 19.87% of the variation between
species was statistically significant (P < 0.001). When the different species were compared with the Wright (Fst) value, genetic
variation between species was confirmed. The data also revealed a moderate rate gene flow between the species. Genetic diversity
was found to be somewhat higher in Central America than in Mexico. 相似文献
7.
Toan Duc Pham Tri Minh Bui Gun Werlemark Tuyen Cach Bui Arnulf Merker Anders S. Carlsson 《Genetic Resources and Crop Evolution》2009,56(5):679-690
Sesame (Sesamum indicum L.) is a traditional oil crop cultivated throughout South East Asia. To estimate the genetic diversity of this crop in parts
at the region, 22 sesame accessions collected in Vietnam and Cambodia were analyzed using 10 RAPD markers. The 10 primers
generated 107 amplification products of which 88 were polymorphic fragments (83%). Genetic diversity of all populations was
Ht = 0.34 when estimated by Nei’s genetic diversity and species diversity was H′sp = 0.513 when estimated by Shannon diversity index. Genetic distance ranged from 0.03 to 0.43, with a mean genetic distance
of 0.23. The unweighted pair group method with arithmetic averages (UPGMA) cluster analysis for the 22 accessions divided
the material in four groups. The dendrogram revealed a clear division among the sesame accessions based on their geographical
region. Interestingly, some geographically distant accessions clustered in the same group, which might indicate the human
factor involved in the spreading of sesame varieties. The high level of polymorphism shown suggests that RAPD techniques can
also be useful for the selection of parents in sesame (Sesamum indicum L.) breeding program and for cultivar differentiation. 相似文献
8.
Arnulf Merker Kalman Lantai 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):48-51
Hexaploid and tetraploid wheats were pollinated by the wild perennial wheat relatives Leymus arenarius, L. mollis, L. racemosus and Thinopyrum junceiforme. Hybrids were obtained from all attempted cross combinations, two of which are reported here for the first time. They are tall and perennial and have the expected chromosome numbers. Strategies for the future use of these hybrids in wheat improvement are discussed and outlined. 相似文献
9.
Numerous microorganisms oxidize sulfur for energy conservation and contribute to the global biogeochemical sulfur cycle. We have determined the 1.7 angstrom-resolution structure of the sulfur oxygenase reductase from the thermoacidophilic archaeon Acidianus ambivalens, which catalyzes an oxygen-dependent disproportionation of elemental sulfur. Twenty-four monomers form a large hollow sphere enclosing a positively charged nanocompartment. Apolar channels provide access for linear sulfur species. A cysteine persulfide and a low-potential mononuclear non-heme iron site ligated by a 2-His-1-carboxylate facial triad in a pocket of each subunit constitute the active sites, accessible from the inside of the sphere. The iron is likely the site of both sulfur oxidation and sulfur reduction. 相似文献
10.
Three thousand tef [Eragrostis tef (Zucc.) Trotter] single panicle derived lines representing 60 populations from western and southern parts of Ethiopia were
characterized for panicle form, pigmentation of lemma and anther, caryopsis color, number of main shoot culm internodes, and
counts of florets/spikelet at the basal, middle and apical parts of the panicle at Debre Zeit Agricultural Research Center
during the 1999 main season. The objectives were to assess the diversity patterns of the germplasm with respect to regions
and altitude zones. Among the eight characters, high Shannon-Weaver diversity indices (H’) were noted for anther color (0.71)
and number of apical spikelet florets (0.68), and the lowest occurred for panicle form (0.40). Monomorphism (H’ = 0.00) was
observed for panicle form, lemma color and number of middle spikelet florets each in three different populations. The overall
diversity index for all populations was 0.53. In the analysis of variance of H’ estimates, substantial (p <0.05) regional differences were obtained for lemma color, number of culm internodes, and counts of middle and basal spikelet
florets. Clinal variation was significant for panicle form, lemma and seed color, and for the overall mean of traits. Over
all traits, mean H’ values declined from 0.60 to 0.46 with an increase in the altitude zone of origin from below 1800 to over
2400 meters above sea level. Overall, the study showed substantial diversity in the test tef germplasm.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献