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921.
Luciana Rossini Pinto Maria Lucia Carneiro Vieira Cláudio Lopes de Souza Jr Anete Pereira de Souza 《Euphytica》2003,134(3):277-286
BR-105 and BR-106 are important tropical maize populations, which were submitted to a high-intensity reciprocal recurrent
selection, generating the IG-3 and IG-4synthetics. Using 30-microsatellite loci,we measured and compared the genetic diversity
of these populations and their synthetics. The populations did not differ significantly regarding the amount of genetic diversity.
As a consequence of selection, genetic variability losses, in terms of mean number of alleles per locus,proportion of polymorphic
loci, and gene diversity did occur and were greater in the synthetic IG-3 than IG-4. In the synthetics, the number of loci
in adherence to Hardy-Weinberg proportions was superior to that observed in the populations. The Wright's mean fixation index
was higher than the mean value expected for outcrossing species (5%) indicating as light excess of homozygotic individuals
in both populations. The genetic distances confirmed the favourable effects of one cycle of recurrent selection, as the synthetics
became more isolated in comparison to the original populations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
922.
The development of commercial sunflower hybrids based on new CMS sources is of special interest for reducing the potential risk of vulnerability to pathogens and for increasing genetic diversity. From 263 test crosses involving nine new CMS sources, i.e. ANL1, ANL2, MAX1, PEF1, PET2, ANN1, ANN2, ANNS and ANN4, five lines were selected as potential restorers for PEF1, PET2 and ANN4. In test crosses between all nine CMS sources and these five restorer lines evaluated in 2 years, seven fully restored hybrids could be identified. These hybrids, based on ANL1, ANL2, MAX1, PEF1, PET2, and ANN4, showed good agronomic performance for plant height, days to flowering, maturity and oil content. Segregation analyses of the F2 populations indicate that a single dominant restorer gene was sufficient to restore pollen production of hybrids based on ANL2, PEF1 and PET2. For restoration of ANN4, two dominant complementary genes are required. In restoration of fertility in the crosses of ANL1 and MAX1 investigated, two dominant genes are involved each of which on its own allows the production of fertile plants. 相似文献
923.
利用若干单株混合提取DNA方法进行玉米群体SSR的分析 总被引:9,自引:1,他引:9
以金皇后玉米群体90个单株:DNA和6个自交系DNA为供试材料,利用15对SSR引物,比较了同一群体4种DNA样品处理(单株DNA样品、3个单株混合DNA样品、10个单株混合DNA样品、15个单株混合DNA样品)的SSR遗传多态性。结果表明,利用单株DNA样品能获得等位基因数、基因频率、基因型杂合度等较全面的遗传信息,适宜进行单个或少量群体的遗传结构研究,但试验工作量大;利用混合DNA样品所能获得的遗传信息有所减少,比较4种DNA样品处理的检测结果发现,15个单株混合样品的检测结果误差较大,而采用3~10个单株DNA混合的样品基本可以反映出一个群体的等位基因数目和SSR带型的差异,由于试验工作量大大减少,可以应用于较多玉米群体间遗传差异的比较。 相似文献
924.
Summary In this study, the application of molecular markers to optimise genetic diversity in a polycross breeding program of perennial
ryegrass (Lolium perenne L.) was evaluated. The genetic diversity among 98 potential parental plants from three maturity groups (early, intermediate
and late flowering) was investigated using amplified fragment length polymorphism (AFLP) markers. For each maturity group,
two polycrosses of six parental plants with contrasting levels of genetic diversity were composed. Average genetic diversity
among parents selected for narrow polycrosses was 36% lower than among parents selected for wide polycrosses. Diversity within
first generation synthetic progenies (Syn1) was proportional to the diversity within the respective parental polycrosses.
However, differences were less pronounced with Syn1 progenies from narrow polycrosses showing 16% reduced diversity when compared
to Syn1 progenies from wide polycrosses. Multivariate analyses allowed for a clear separation of the six Syn1 progenies based
on AFLP markers and demonstrated their genetic distinctness. Evaluation of dry matter yield, date of ear emergence and stem
length of Syn1 and Syn2 progenies showed progenies from wide polycrosses to be constantly higher yielding when compared to
progenies from narrow polycrosses. On the other hand, there was no significant difference in variability for the two morphological
traits between progenies of narrow- and wide polycrosses. The results presented here provide evidence for an efficient application
of molecular markers to select genetically diverse polycross parents which resulted in an average yield increase of 3.8%. 相似文献
925.
AFLP markers were used to assess the genetic diversity of 77 breeding lines from three of the world's major canola qualityBrassica juncea breeding programs from Canada (Agriculture and Agri-Food Canada and Saskatchewan Wheat Pool) and Australia (Agriculture Victoria).
The objectives of the paper were to assess the genetic diversity within and between these three breeding programs and to assess
genetic diversity of the canola quality germplasm as compared to mustard quality B. juncea. Fifteen lines of mustard quality B. juncea from India, China, Russia and Australia were also included in the investigation. Ten EcoR1/Mse1 based primer pairs generated 751 scorable fragments with an average of 26 polymorphic bands per primer pair (35%). Similarity
coefficients were calculated using the Simple Matching coefficient and adendrogram was developed using the UPGMA procedure,
resulting in germplasm being partitioned into five main groups. Line specific markers were discovered that have potential
in enhancing the efficiency of individual breeding programs using breeding techniques like accelerated backcrossing. Further
understanding the genetic diversity within and between programs has implications for future breeding and collaboration within
and between the three programs.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
926.
The extent of genetic diversity and the genetic relationships among 94 coconut varieties/populations (51 Talls and 43 Dwarfs)
representing the entire geographic range of cultivation/distribution of the coconut was assessed using 12 pairs of coconut
micro satellite primers. A high level of genetic diversity was observed in the collection with the mean gene diversity of
0.647±0.139, with that of the mean gene diversity of Talls 0.703±0.125 and 0.374±0.204 of Dwarfs. A phenetic tree based on
DAD genetic distances clustered all the 94 varieties/populations into two main groups, with one group composed of all the Talls
from southeast Asia, the Pacific, west coast of Panama, and all Dwarfs and the other of all Talls from south Asia, Africa,
and the Indian Ocean coast of Thailand. The allele distribution of Dwarfs highlighted a unique position of Dwarf palms from
the Philippines exhibiting as much variation as that in the Tall group. The grouping of all Dwarfs representing the entire
geographic distribution of the crop with Talls from southeast Asia and the Pacific and the allele distribution between the
Tall and Dwarf suggest that the Dwarfs originated from the Tall forms and that too from the Talls of southeast Asia and the
Pacific. Talls from Pacific Islands recorded the highest level of genetic diversity (0.6±0.26) with the highest number of
alleles (51) among all the regions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
927.
Chloroplast DNA variation in 96 Prunus avium L. cultivars was assessed and compared with the results of a previous study of cpDNA diversity in 23 wild populations of the species. The polymerase chain reaction‐restriction fragment length polymorphism method was used in these studies. Approximately 9% of the chloroplast genome was analyzed, using five universal primer pairs and three restriction enzymes. Ten polymorphic fragments were common to both the wild and sweet cherry; eight polymorphic fragments were found only in the wild cherry. In the cultivars, all mutations were small (5‐30 bp) indels. In the wild populations, a point mutation was also detected in addition to indels. The mutational combinations revealed three haplotypes in the cultivars, which are the main haplotypes in the wild cherry populations. Chloroplast DNA diversity in wild cherry is higher (16 haplotypes) than in sweet cherry cultivars (three haplotypes). The probable wild origin of the sweet cherry cultivars in the maternal line, on the basis of haplotypic similarity, was discussed. 相似文献
928.
929.
Red clover (Trifolium pratense L.) is one of the main forage species of temperate regions. Cultivars of red clover are heterogeneous which makes their genetic
analysis difficult. We applied RAPDs (Random Amplifed Polymorphic DNA) in order to assess the genetic relationship and levels
of genetic variability existing among a group of 16 elite red clover parents organised in four subsets of 4 parents each.
Out of 55 primers 21 provided reproducible results. A total of 135 reliable and polymorphic RAPD bands were detected which
were used to estimate genetic distances among pair-wise combinations of elite parents. Nei and Li's similarity values ranged
from 0.60 to 0.77, with a mean of 0.66, which reflects a rather high genetic variability among the genotypes evaluated. Lower
levels of genetic variability, as detected by polymorphic loci and mean heterogeneity values, were detected in a subset of
parents selected for resistance to the stem nematode. Cluster analyses resolved the different sets of parents in a manner
consistent with what is known from their breeding origins. An Analysis of Molecular Variance detected substantial levels of
variation within subsets of parents. RAPDs represent a valuable source of genetic information for red clover breeding programmes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
930.
Fifteen alfalfa populations consisting of six public cultivars and nine historically recognized sources of alfalfa germplasm in North American cultivars were examined using sequence related amplified polymorphisms (SRAPs). Three bulk DNA samples from each population were evaluated with fourteen different SRAP primer pairs. This resulted in 249 different amplicons, of which over 90% were polymorphic. A dendrogram from the analysis suggests that the public cultivars are quite diverse from all the historical sources of germplasm. The highest mean genetic similarity among the nine original sources of Medicago germplasm was 0.85 between PI 536535 (Peruvian) and 536536 (Indian), while the lowest (0.47) was between PI 560333 (M. falcata) and 536539 (African). The highest mean genetic similarity among the nine original sources of Medicago germplasm and the public alfalfa cultivars was 0.78 between PI 536532 (Ladak) and Vernal, while the lowest (0.59) was between PI 536539 (African) and Oneida. Relationships based on SRAP analysis appear to generally concur with expected relationships based on fall dormancy. This report demonstrates that SRAPs are a promising marker system for detecting polymorphisms in alfalfa. 相似文献