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1.
Bradshaw JE Dale MF Mackay GR 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,107(1):36-42
A potato breeding strategy is presented which avoids the common but ineffective practice of intense early-generation visual selection between seedlings in a glasshouse and spaced plants at a seed site. Once pair crosses have been made, progeny tests are used to discard whole progenies before starting conventional within-progeny selection at the unreplicated small-plot stage. Clones are also visually selected from the best progenies for use as parents in the next cycle of crosses whilst they are multiplied to provide enough tubers for assessment of their yield and quality. Mid-parent values, as well as progeny tests, are then used to select between the resultant crosses. Material from other breeding programmes can be included in the parental assessments and used in the next cycle of crosses if superior. Finally, in seeking new cultivars, the number of clones on which to practise selection is increased by sowing more true seed of the best progenies, but without selection until the small-plot stage. Traits considered are resistance to late blight [ Phytophthora infestans (Mont.) de Bary] and to the white potato cyst nematode [ Globodera pallida (Stone)], fry colour and tuber yield and appearance, as visually assessed by breeders. The theoretical superiority of the strategy for seeking new cultivars lies in being able to practise between-cross selection for a number of economically important traits within 1 or 2 years of making crosses, something that is not possible on individuals as seedlings in the glasshouse or spaced plants at the seed site. This also means that full-sib family selection can be operated on a 3-year cycle, an improvement on current practice of clonal selection on what is often at least a nine-year cycle. New cultivars can be sought with more confidence from the best progenies in each cycle, and modern methods of rapid multiplication used to reduce the number of clonal generations required to find the best clones. 相似文献
2.
Wu XL Jannink JL 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,108(7):1434-1442
In a population intended for breeding and selection, questions of interest relative to a specific segregating QTL are the variance it generates in the population, and the number and effects of its alleles. One approach to address these questions is to extract several inbreds from the population and use them to generate multiple mapping families. Given random sampling of parents, sampling strategy may be an important factor determining the power of the analysis and its accuracy in estimating QTL variance and allelic number. We describe appropriate multiple-family QTL mapping methodology and apply it to simulated data sets to determine optimal sampling strategies in terms of family number versus family size. Genomes were simulated with seven chromosomes, on which 107 markers and six QTL were distributed. The total heritability was 0.60. Two to ten alleles were segregating at each QTL. Sampling strategies ranged from sampling two inbreds and generating a single family of 600 progeny to sampling 40 inbreds and generating 40 families of 15 progeny each. Strategies involving only one to five families were subject to variation due to the sampling of inbred parents. For QTL where more than two alleles were segregating, these strategies did not sample QTL alleles representative of the original population. Conversely, strategies involving 30 or more parents were subject to variation due to sampling of QTL genotypes within the small families obtained. Given these constraints, greatest QTL detection power was obtained for strategies involving five to ten mapping families. The most accurate estimation of the variance generated by the QTL, however, was obtained with strategies involving 20 or more families. Finally, strategies with an intermediate number of families best estimated the number of QTL alleles. We conclude that no overall optimal sampling strategy exists but that the strategy adopted must depend on the objective.Communicated by P. Langridge 相似文献
3.
Jiankang Wang Scott C. Chapman David G. Bonnett Greg J. Rebetzke 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(1):65-74
Plant breeders simultaneously select for qualitative traits controlled by one or a small number of major genes, as well as
for polygenic traits controlled by multiple genes that may be detected as quantitative trait loci (QTL). In this study, we
applied computer simulation to investigate simultaneous selection for alleles at both major and minor gene (as QTL) loci in
breeding populations of two wheat parental lines, HM14BS and Sunstate. Loci targeted for selection included six major genes
affecting plant height, disease resistance, and grain quality, plus 6 known and 11 “unidentified” QTL affecting coleoptile
length (CL). Parental line HM14BS contributed the target alleles at two of the major gene loci, while parental line Sunstate
contributed target alleles at four loci. The parents have similar plant height, but HM14BS has a longer coleoptile, a desirable
attribute for deep sowing in rainfed environments. Including the wild-type allele at the major reduced-height locus Rht-D1, HM14BS was assumed to have 13 QTL for increased CL, and Sunstate four; these assumptions being derived from mapping studies
and empirical data from an actual HM14BS/Sunstate population. Simulation indicated that compared to backcross populations,
a single biparental F1 cross produced the highest frequency of target genotypes (six desired alleles at major genes plus desired QTL alleles for
long CL). From 1,000 simulation runs, an average of 2.4 individuals with the target genotype were present in unselected F1-derived doubled haploid (DH) or recombinant inbred line (RIL) populations of size 200. A selection scheme for the six major
genes increased the number of target individuals to 19.1, and additional marker-assisted selection (MAS) for CL increased
the number to 23.0. Phenotypic selection (PS) of CL outperformed MAS in this study due to the high heritability of CL, incompletely
linked markers for known QTL, and the existence of unidentified QTL. However, a selection scheme combining MAS and PS was
equally as efficient as PS and would result in net savings in production and time to delivery of long coleoptile wheats containing
the six favorable alleles. 相似文献
4.
Positive assortative mating with family size as a function of predicted parental breeding values
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While other investigations have described benefits of positive assortative mating (PAM) for forest tree breeding, the allocation of resources among mates in these studies was either equal or varied, using schemes corresponding only to parental rank (i.e., more resources invested in higher-ranking parents). In this simulation study, family sizes were proportional to predicted midparent BLUP values. The distribution of midparent BLUP values was standardized by a constant, which was varied to study the range of distributions of family size. Redistributing progenies from lower- to higher-ranking families to a point where an equal number of progenies were still selected out of each family to the next generation caused minimal change in group coancestry and inbreeding in the breeding population (BP), while the additive genetic response and variance in the BP were both greatly enhanced. This generated additional genetic gains for forest plantations by selecting more superior genotypes from the BP (compared to PAM with equal family sizes) for production of improved regeneration materials. These conclusions were verified for a range of heritability under a polygenic model and under a mixed-inheritance model with a QTL contributing to the trait variation. 相似文献
5.
Felicity Claire Atkin Mark J. Dieters Joanne K. Stringer 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(3):555-565
Sugarcane breeders in Australia combine data across four selection programs to obtain estimates of breeding value for parents.
When these data are combined with full pedigree information back to founding parents, computing limitations mean it is not
possible to obtain information on all parents. Family data from one sugarcane selection program were analysed using two different
genetic models to investigate how different depths of pedigree and amount of data affect the reliability of estimating breeding
value of sugarcane parents. These were the parental and animal models. Additive variance components and breeding values estimated
from different amounts of information were compared for both models. The accuracy of estimating additive variance components
and breeding values improved as more pedigree information and historical data were included in analyses. However, adding years
of data had a much larger effect on the estimation of variance components of the population, and breeding values of the parents.
To accurately estimate breeding values of all sugarcane parents, a minimum of three generations of pedigree and 5 years of
historical data were required, while more information (four generations of pedigree and 7 years of historical data) was required
when identifying top parents to be selected for future cross pollination. 相似文献
6.
Rodomiro Ortiz Stanley J. Peloquin Rosanna Freyre Masaru Iwanaga 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,82(5):602-608
Summary The objective of this research was to compare the efficiency of the 4x×2x breeding scheme with the traditional 4x×4x method with respect to potato improvement. The basis for such a comparison was the parental value of four 2x and four 4x male parents from the International Potato Center (CIP) as measured by multitrait selection and progeny testing. The 2x parents produced 2n pollen by parallel spindles at anaphase II, which is genetically equivalent to a first division restitution (FDR) mechanism. Both 2x and 4x parents were crossed with four common 4x female parents. Thus, 32 families were evaluated over 2 years at four Peruvian locations. A selection index which considered tuber yield, tuber number, average tuber weight and specific gravity was used for multitrait selection. Three FDR 2x parents had better selection index scores than the 4x parents over the four locations. Estimates of broad-sense heritability for total yield using different number of replications and locations were calculated by using the variance components. The 4x × 2x breeding scheme was found to be better than the traditional 4x × 4x method since fewer replications and locations are required to evaluate tuber yield in 4x × 2x progenies than in 4x × 4x progenies. The FDR 2x parents were also better material than the 4x parents for testing combining ability for tuber yield of the 4x progenitors. This could be the result of the mode of FDR 2n pollen formation. The pollen of FDR 2x parents is more heterozygous, but more homogenous than n pollen from 4x parents.Paper from the Laboratory of Genetics. Research supported by the College of Agricultural and Life Sciences; International Potato Center; USDA-CRGO-88-37234 3619, and Frito-Lay, Inc., USA 相似文献
7.
Selective recovery of founder genetic diversity in aquacultural broodstocks and captive, endangered fish populations 总被引:2,自引:0,他引:2
Hatchery broodstocks used for genetic conservation or aquaculture may represent their ancestral gene pools rather poorly. This is especially likely when the fish that found a broodstock are close relatives of each other. We re-analysed microsatellite data from a breeding experiment on red sea bream to demonstrate how lost genetic variation might be recovered when gene frequencies have been distorted by consanguineous founders in a hatchery. A minimal-kinship criterion based on a relatedness estimator was used to select subsets of breeders which represented the maximum number of founder lineages (i.e., carried the fewest identical copies of ancestral genes). UPGMA clustering of Nei's genetic distances grouped these selected subsets with the parental gene pool, rather than with the entire, highly drifted offspring generation. The selected subsets also captured much of the expected heterozygosity and allelic diversity of the parental gene pool. Independent pedigree data on the same fish showed that the selected subsets had more contributing parents and more founder equivalents than random subsets of the same size. The estimated mean coancestry was lower in the selected subsets, meaning that inbreeding in subsequent generations would be lower if they were used as breeders. The procedure appears suitable for reducing the genetic distortion due to consanguineous and over-represented founders of a hatchery gene pool. 相似文献
8.
North American study on essential derivation in maize: inbreds developed without and with selection from F2 populations 总被引:2,自引:0,他引:2
R. Bernardo A. L. Kahler 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(6-7):986-992
An essentially derived variety largely retains the characteristics of a parental or ancestral variety. A consensus has not
been reached regarding the threshold for declaring essential derivation in maize (Zea mays L.), partly because benchmark data are lacking. Our objective in this study, commissioned by the American Seed Trade Association,
was to determine the range of parental contribution among maize inbreds developed without and with selection. Seed companies
in North America contributed existing proprietary data on the molecular marker similarity of 100 or more families, developed
without selection from F2 populations, with each of their parents. The companies also sent us seed samples of elite inbreds, developed with selection
from F2 populations, for analysis using 60 RFLP marker loci and 20 SSR marker loci. Among the families developed without selection,
the average parental contribution was close to the expected value of 0.50 for F2 populations. Specific families received up to 79% of their alleles from one parent. Although selection tended to increase
the frequency of such transgressive segregants, it did not necessarily increase the maximum parental contribution in an F2 population. Parental contributions were consistent between the elite inbreds and their early-generation families. We conclude
that inbreds with 70% to nearly 80% of their genome derived from one parent can be obtained from an F2 population. Further empirical data would be valuable particularly for backcross populations, which were not available in
this study.
Received: 21 June 2000 / Accepted: 28 July 2000 相似文献
9.
SSR heterogenic patterns of parents for marking and predicting heterosis in rice breeding 总被引:9,自引:0,他引:9
The most important concerns of hybrid rice breeders are selection of donors to improve parental lines and prediction of hybrid performance. In this study, SSR molecular marker technology and a half-diallel method were used to address these related hybrid production issues. The results show that genetic diversity among the parental lines is certainly related to heterosis. The heterozygosity of each parental pair is significantly associated with the general combining ability, not with the specific combining ability. However, neither genetic diversity nor heterozygosity is a good indicator for predicting heterosis. From these results, it is suggested that donors for improving parents of hybrids be selected from the improved inbred lines by conventional breeding programs. In this investigation, we also discovered that four favorable alleles and six favorable heterogenic patterns on the parental lines significantly contribute to the heterosis of their hybrids in grain yield, whereas six unfavorable alleles and six unfavorable heterogenic patterns significantly reduce heterosis. These noticeable findings could be, in practice, useful for hybrid rice breeding programs with SSR marker-assisted selection. It is suggested that the optimal combinations with the superior grain yield could be bred out by assembling those favorable alleles into their parental lines and by removing the unfavorable alleles from the parental lines. This study also indicates that there is still a great heterosis potential to be exploited in indica/indica hybrids by the same strategy. In indica/japonica hybrid breeding programs, it may also be important to remove unfavorable alleles rather than broaden genetic diversity or heterozygosity of the parents. 相似文献
10.
N. R. Wray J. A. Woolliams R. Thompson 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,87(7):878-892
For populations undergoing mass selection, previous studies have shown that the rate of inbreeding is directly related to the mean and variance of long-term contributions from ancestors to descendants, and thus prediction of the rate of inbreeding can be achieved via the prediction of long-term contributions. In this paper, it is shown that the same relationship between the rate of inbreeding and long-term contributions is found when selection is based on an index of individual and sib records (index selection) and where sib records may be influenced by a common environment. In these situations, rates of inbreeding may be considerably higher than under mass selection. An expression for the rate of inbreeding is derived for populations undergoing index selection based on variances of (one-generation) family size and incorporating the concept of long-term selective advantage. When the mating structure is hierarchical, and when half-sib records are included in the index, the correlation between parental breeding values and the index values of their offspring is higher for male parents than female parents. This introduces an important asymmetry between the contributions of male and female ancestors to the evolution of inbreeding which is not present when selection is based on individual and/or full-sib records alone. The prediction equation for index selection accounts for this asymmetry. The prediction is compared to rates of inbreeding calculated from simulation. The prediction is good when family size is small relative to the number selected. The reasons for overprediction in other situations are discussed. 相似文献
11.
Guillaume Gayet Matthieu Guillemain Maurice Benmergui François Mesleard Thierry Boulinier Jean‐Philippe Bienvenu Hervé Fritz Joël Broyer 《Oikos》2011,120(6):801-812
Foragers in patchy environments do not only select sites for single patch characteristics, but also have to consider the local environment of such patches. We studied habitat selection by mute swans Cygnus olor in a wide and heterogeneous fishpond region (the Dombes, eastern France). In this study, we considered fishpond isolation, resource quality within fishponds and breeding status of mute swans during both summer and winter. Mute swans did not select aquatic habitat randomly within the landscape. During summer, the population spread preferentially on medium to large fishponds, in subregions with numerous or closely related waterbodies, without generating a clumped distribution of birds. In addition to a positive effect of local fishpond number (2 km radius), breeding birds also responded positively to fishpond size. Non‐breeders selected fishponds mainly according to their size. Intraspecific territoriality did not appear to limit the presence of non‐breeders (i.e. moulting flocks), since both breeders and non‐breeders could coexist on the larger fishponds. During winter, mute swans used medium to large reflooded fishponds after summer drainage. The surrounding aquatic environment of fishponds played a minor role in determining flocking, compared to actual patch quality. Flocking occurred on large fishponds that had reflooded after having dried the summer before, whatever the agricultural cultivation practiced in the summer following drainage. The results suggest that geographical aspects should be taken into account when considering the potential impact of this expanding species within such ecosystems, and also in more general management policies dealing with aquatic habitats for waterbird populations. 相似文献
12.
Domestication and breeding share a common feature of population bottlenecks followed by significant genetic gain. To date, no crop models for investigating the evolution of genetic variance, selection response, and population diversity following bottlenecks have been developed. We developed a model artificial selection system in the laboratory using rapid-cycling Brassica rapa. Responses to 10 cycles of recurrent selection for cotyledon size were compared across a broad population founded with 200 individuals, three bottleneck populations initiated with two individuals each, and unselected controls. Additive genetic variance and heritability were significantly larger in the bottleneck populations prior to selection and this corresponded to a heightened response of bottleneck populations during the first three cycles. However, the overall response was ultimately greater and more sustained in the broad population. AFLP marker analyses revealed the pattern and extent of population subdivision were unaffected by a bottleneck even though the diversity retained in a selection population was significantly limited. Rapid gain in genetically more uniform bottlenecked populations, particularly in the short term, may offer an explanation for why domesticators and breeders have realized significant selection progress over relatively short time periods. 相似文献
13.
Dr. R. J. Parker L. D. McGilliard J. L. Gill 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1969,39(8):365-370
Summary Effects of truncation selection of a primary trait upon genetic correlation with a secondary trait were examined over 30 generations in genetic populations simulated by computer. Populations were 24 males and 24 females mated randomly with replacement; number of offspring was determined by intensity of selection. Each trait was controlled by 48 loci segregating independently, effects were equal at every locus, and gene frequency was arbitrarily set at 0.5 at each locus in the initial generation. All combinations of three genetic correlations, three intensities of selection, and three environmental variances were simulated. Gene action was additive. Genetic correlation was set by number of loci which affected both traits and was measured each generation as the product-moment correlation of genotypic values and estimated by two methods of combining phenotypic covariances between parent and offspring.Genetic correlations in each offspring generation remained consistently near initial correlations for all environmental variances when fraction of offspring saved as parents was as large as one-half. When the fraction of offspring saved was as small as one-fifth, genetic correlations decreased but most rapidly with heritability high and after the 15th generation of selection. Truncation selection caused genetic correlation to decrease in those offspring selected to become parents of the next generation. Amount of reduction depended on heritability of the selected trait rather than on degree of truncation selection. Estimates of genetic correlation from phenotypic covariances between parent and offspring fluctuated markedly from real correlations in the small populations simulated.Michigan Agricultural Experiment Station Journal Article 4836. Part of North Central Regional Project NC-2. 相似文献
14.
Heckenberger M Bohn M Frisch M Maurer HP Melchinger AE 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(3):598-608
Genetic similarities (GS) based on molecular markers have been proposed as a tool for identification of essentially derived varieties (EDVs). Nevertheless, scientifically reliable criteria for discrimination of EDVs and independently derived varieties with GS estimates are scanty, and implementation into practical breeding has not yet taken place. Our objectives were to (1) assess the influence of chromosome number and length, marker density, and distribution, as well as the degree of polymorphism between the parental inbreds on the distribution of GS between parental inbreds and their progenies [GS(P1,O)] derived from F2 and different backcross populations and (2) evaluate these factors with regard to the power for distinguishing F2- versus BC1- and BC1- versus BC2-derived lines with molecular markers. We developed an approach based on statistical test theory for the identification of EDVs with molecular markers. Standard deviations and overlaps of distributions of GS(P1,O) of F2-, BC1-, and BC2-derived lines were smaller with (1) increasing chromosome number and length, (2) increasing marker density, and (3) uniformly instead of randomly distributed markers, approaching a lower boundary determined by the genetic parameters. The degree of polymorphism between the parental inbreds influenced the power only if the remaining number of polymorphic markers was low. Furthermore, suggestions are made for (1) determining the number of markers required to ascertain a given power and (2) EDV identification procedures. 相似文献
15.
The number of inbreeding generations required to produce homozygotes may be reduced if the more homozygous individuals in each breeding generation are selected phenotypically in the segregating progenies for further inbreeding. To demonstrate this, inbred lines and their F1, S1, and S2 progenies were studied for number of days from planting to anthesis, plant height and total leaf number. The data indicated that a high degree of control of rate of inbreeding may be obtained by proper use of heterotic characteristics in selection. The technique is a simple one: the selection of those individuals in a segregating array that most closely approach the characteristics of the ultimate homozygotes obtainable from the population. If these traits are undefined, then simple negative selection for heterotic attributes should suffice. In an S1 progeny of maize, an individual with the same number of leaves and (1) as short as and (2) as slow to flower as the parental inbreds will be likely to be more homozygous than its taller and earlier flowering sibs of like leaf number. Since the inbreeder’s aim is not homozygosis per se but the development of agronomically useful homozygotes, the population dealt with should be sufficiently large to permit intense selection for outstanding individuals among the more homozygous members of each generation of selection. 相似文献
16.
云南红花种质资源主要农艺性状的遗传多样性分析 总被引:7,自引:0,他引:7
为加强红花种质资源的研究利用,对筛选出的66份云南红花优异种质资源16个形态性状进行聚类分析与主成分分析。结果表明:云南红花种质资源具有丰富的遗传多样性,多样性指数最高的是果球着粒数,其次是株高、最末分枝高度和千粒重;性状变异系数最大的是分枝总数,其次分别是单株有效果球数和第一分枝高度,最小的为顶果球直径;基于各种质间形态性状的遗传差异,把66份红花种质聚类并划分为6大类群。第Ⅰ类群可作为有增产潜力的亲本材料,第Ⅲ类群可作为高产量目标选育的亲本,第Ⅳ类群可作为大粒型选育亲本,第Ⅴ类群可作为高含油量选育目标亲本,第Ⅵ类群既是大粒型又是高含油量双重选育目标亲本。11个数量性状的主成分分析结果表明,前4个主成分累计贡献率达82.59%,第一主成分反映植株高度,第二主成分反映产量构成因子,第三、第四主成分分别反映千粒重和果球着粒数。研究结果表明云南红花地方种质资源的变异较大,遗传较丰富。 相似文献
17.
Hung HY Browne C Guill K Coles N Eller M Garcia A Lepak N Melia-Hancock S Oropeza-Rosas M Salvo S Upadyayula N Buckler ES Flint-Garcia S McMullen MD Rocheford TR Holland JB 《Heredity》2012,108(5):490-499
Appropriate selection of parents for the development of mapping populations is pivotal to maximizing the power of quantitative trait loci detection. Trait genotypic variation within a family is indicative of the family's informativeness for genetic studies. Accurate prediction of the most useful parental combinations within a species would help guide quantitative genetics studies. We tested the reliability of genotypic and phenotypic distance estimators between pairs of maize inbred lines to predict genotypic variation for quantitative traits within families derived from biparental crosses. We developed 25 families composed of ~200 random recombinant inbred lines each from crosses between a common reference parent inbred, B73, and 25 diverse maize inbreds. Parents and families were evaluated for 19 quantitative traits across up to 11 environments. Genetic distances (GDs) among parents were estimated with 44 simple sequence repeat and 2303 single-nucleotide polymorphism markers. GDs among parents had no predictive value for progeny variation, which is most likely due to the choice of neutral markers. In contrast, we observed for about half of the traits measured a positive correlation between phenotypic parental distances and within-family genetic variance estimates. Consequently, the choice of promising segregating populations can be based on selecting phenotypically diverse parents. These results are congruent with models of genetic architecture that posit numerous genes affecting quantitative traits, each segregating for allelic series, with dispersal of allelic effects across diverse genetic material. This architecture, common to many quantitative traits in maize, limits the predictive value of parental genotypic or phenotypic values on progeny variance. 相似文献
18.
Ksenija Taški-Ajduković Nevena Nagl Dragan Milić Slobodan Katić Miroslav Zorić 《Central European Journal of Biology》2014,9(8):768-776
The aim of investigation was to evaluate genetic variation and relationship among alfalfa populations and their offspring, with minimal cost, by using DNA marker analysis. RAPD analysis was performed on bulked DNA samples of five alfalfa parental populations and their progenies: 20 F1 populations from reciprocal diallel crosses and five S1 populations from self-pollination. Twenty primers generated 217 bands, ranging in size from 300 to 6000 bp, with the average number of bands per primer of 10.85 and polymorphism information content of 0.246. Percentage of polymorphic loci, effective number of alleles, expected heterozygosity and Shannon’s information index were used to estimate genetic variation. Higher diversity was observed in F1 progeny populations, while genetic variation in parental populations and S1 progenies remained similar. The genetic relatedness of alfalfa populations was analysed by UPGMA and Bayesian model-based clustering approach. In both types of analysis selfpollinated progenies were grouped. Furthermore, the hybrid offspring where Zuzana, and RSI 20 were maternal parents were placed in separate groups. The results indicate that use of RAPD markers on bulked DNA samples can be fast and cost-effective way for differentiation of alfalfa parental populations and their offspring, as well as for evaluation of their genetic relationships. 相似文献
19.
运用随机扩增多态性DNA(RandomamplifiedpolymorphicDNA,RAPD)技术对源于两个香菇(Lentinulaedodes)双核菌株的孢子单核体、原生质体单核体及其杂交后代进行了基因组DNA多态性分析。用9个随机引物共扩增出116条DNA片段,其中82.5%具有多态性。综合分析9个随机引物的扩增谱带,可将所有供试亲本单核体清楚地分开,且早核体聚类分析的结果与其来源及遗传背景相吻合。此外,用两个双核亲本菌株的各4个不同交配型的孢子单核体两两支配所得的所有杂交组合,也均可与双核亲本菌株明确地区分开来。因此,在杂交育种中,RAPD分析可为亲本的选配及杂种的鉴定提供可靠依据。 相似文献
20.
Tobias A. Schrag Jens Möhring Hans Peter Maurer Baldev S. Dhillon Albrecht E. Melchinger Hans-Peter Piepho Anker P. Sørensen Matthias Frisch 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,118(4):741-751
In hybrid breeding, the prediction of hybrid performance (HP) is extremely important as it is difficult to evaluate inbred
lines in numerous cross combinations. Recent developments such as doubled haploid production and molecular marker technologies
have enhanced the prospects of marker-based HP prediction to accelerate the breeding process. Our objectives were to (1) predict
HP using a combined analysis of hybrids and parental lines from a breeding program, (2) evaluate the use of molecular markers
in addition to phenotypic and pedigree data, (3) evaluate the combination of line per se data with marker-based estimates,
(4) study the effect of the number of tested parents, and (5) assess the advantage of haplotype blocks. An unbalanced dataset
of 400 hybrids from 9 factorial crosses tested in different experiments and data of 79 inbred parents were subjected to combined
analyses with a mixed linear model. Marker data of the inbreds were obtained with 20 AFLP primer–enzyme combinations. Cross-validation
was used to assess the performance prediction of hybrids of which no or only one parental line was testcross evaluated. For
HP prediction, the highest proportion of explained variance (R
2), 46% for grain yield (GY) and 70% for grain dry matter content (GDMC), was obtained from line per se best linear unbiased
prediction (BLUP) estimates plus marker effects associated with mid-parent heterosis (TEAM-LM). Our study demonstrated that
HP was efficiently predicted using molecular markers even for GY when testcross data of both parents are not available. This
can help in improving greatly the efficiency of commercial hybrid breeding programs. 相似文献