共查询到20条相似文献,搜索用时 15 毫秒
1.
M. N. Shapturenko L. A. Tarutina L. A. Mishin A. V. Kilchevsky L. V. Khotyleva 《Russian Journal of Genetics》2014,50(2):123-130
The identification of perspective parental lines for the creation of high-yield hybrids is the most labor-consuming stage of selection, because it needs extensive trials of combining ability. Based on evaluation of the genetic divergence of the parental lines, the prediction accuracy of F1 hybrids performance was investigated. The value of the divergence was calculated using biometric and molecular methods, such as inter simple sequence repeats (ISSR) and random amplified polymorphic DNA (RAPD). Based on estimates of divergence, 10 lines were chosen for cyclic cross (scheme I) and testcross (scheme II). In most crosses, the F1 hybrids were significantly superior to the parents in the main economically valuable traits. The level of heterosis was higher among hybrids of scheme I. Analysis of the relationship between parental divergence and F1 performance showed that the hybrid productivity of scheme I was predetermined by ISSR divergence in 86%, and productivity was caused by RAPD divergence in 69%, whereas the F1 yield of scheme II was not related to the value of genetic distances. Since the values of DNA divergence were closely associated both with midparent level and F1 performance, we assumed that part of the polymorphic DNA fragments of the parental lines of scheme I is related to heterotic loci (HTL), which may be considered potential key markers for the heterotic selection of the sweet pepper. 相似文献
2.
Zha Renming Ling Yinghua Yang Zhenglin Zhao Fangming Zhong Bingqiang Xie Rong Sang Xianchun He Guanghua 《Molecular breeding : new strategies in plant improvement》2008,22(3):467-476
One hundred and fifty-one rice hybrids produced in two sets of half-dialell crosses and their parents (13 cytoplasmic male
sterile lines and 19 restorers) were used to predict the F1 performances of seven yield traits through the parental genetic distances (GD) based on SSR markers. The positive loci (PL)
and effect-increasing loci (IL), which were screened from SSR polymorphic loci by the F1 traits of 32 parents, together with total loci (TL), were utilized to estimate parental GD and the models were found to predict
the traits of hybrids derived from different parents, fixed parents, and different environments, respectively. The results
were as follows: (1) 550 polymorphic loci were detected from 174 SSR markers: a dendrogram based on these loci could separate
all the sterile and restorer lines used in the present study, which indicated that parental genetic diversity of F1 was large; (2) the correlations between F1 traits and parental GDs based on IL ranged from 0.61 to 0.87 with a mean of 0.76, and they were higher than those on TL or
on PL; (3) predictions based on IL for F1 traits (except grain weight per plant) derived from different environments were ideal, but worse for F1 traits derived from different parents; and (4) IL was more effective than TL and PL in predicting traits of F1 with fixed parents, and predictions for fixed restorer combinations were more effective than those for fixed sterile line
combinations. These results should facilitate molecular prediction for hybrid yield and other traits by means of both elite
sterile and restorer lines. 相似文献
3.
Performance prediction of F1 hybrids between recombinant inbred lines derived from two elite maize inbred lines 总被引:1,自引:0,他引:1
Tingting Guo Huihui Li Jianbing Yan Jihua Tang Jiansheng Li Zhiwu Zhang Luyan Zhang Jiankang Wang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(1):189-201
Selection of recombinant inbred lines (RILs) from elite hybrids is a key method in maize breeding especially in developing countries. The RILs are normally derived by repeated self-pollination and selection. In this study, we first investigated the accuracy of different models in predicting the performance of F1 hybrids between RILs derived from two elite maize inbred lines Zong3 and 87-1, and then compared these models through simulation using a wider range of genetic models. Results indicated that appropriate prediction models depended on genetic architecture, e.g., combined model using breeding value and genome-wide prediction (BV+GWP) has the highest prediction accuracy for high V D/V A ratio (>0.5) traits. Theoretical studies demonstrated that different components of genetic variance were captured by different prediction models, which in turn explained the accuracy of these models in predicting the F1 hybrid performance. Based on genome-wide prediction model (GWP), 114 untested F1 hybrids possibly having higher grain yield than the original F1 hybrid Yuyu22 (the single cross between Zong3 and 87-1) have been identified and recommended for further field test. 相似文献
4.
The effect of population structure on the relationship between heterosis and heterozygosity at marker loci 总被引:5,自引:0,他引:5
A. Charcosset L. Essioux 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(2-3):336-343
The relationship between heterozygosity at neutral marker loci and heterosis of F1 hybrids is investigated using a theoretical model. Results emphasize that linkage disequilibrium between the markers and the loci implicated in heterosis [quantitative trait loci (QTLs) that exhibit dominance effects] is a necessary condition to finding a correlation (
mh
) between heterozygosity at marker loci and the heterosis. The effect of population structure, in which the parental inbred lines of the hybrids belong to different heterotic groups, is considered.
mh
is investigated for: (1) hybrids between lines that belong to the same heterotic group (within-group hybrids); (2) hybrids between lines that belong to different groups (between-group hybrids); and (3) all hybrids, both within and between-groups. Within a group, significant values of (
mh
) may arise because of linkage disequilibrium generated by drift. At the between-group level, no correlation is expected since link-age disequilibrium should differ randomly from one group to the other, which is consistent with recent experimental results. Possible ways to achieve prediction of the heterosis in this situation are discussed. When all hybrids are considered simultaneously, divergence of allelic frequencies among groups for the markers and the QTLs produces a correlation between heterosis and heterozygosity at marker loci. This correlation increases with the number of markers that are considered. 相似文献
5.
Ricardo J. Pereira Felipe S. Barreto Ronald S. Burton 《Evolution; international journal of organic evolution》2014,68(1):204-215
Early generations of hybrids can express both genetic incompatibilities and phenotypic novelty. Insights into whether these conflicting interactions between intrinsic and extrinsic selection persist after a few generations of recombination require experimental studies. To address this question, we use interpopulation crosses and recombinant inbred lines (RILs) of the copepod Tigriopus californicus, and focus on two traits that are relevant for the diversification of this species: survivorship during development and tolerance to thermal stress. Experimental crosses between two population pairs show that most RILs between two heat‐tolerant populations show enhanced tolerance to temperatures that are lethal to the respective parentals, whereas RILs between a heat‐tolerant and a heat‐sensitive population are intermediate. Although interpopulation crosses are affected by intrinsic selection at early generational hybrids, most of the sampled F9 RILs have recovered fitness to the level of their parentals. Together, these results suggest that a few generations of recombination allows for an independent segregation of the genes underlying thermal tolerance and cytonuclear incompatibilities, permitting certain recombinant lineages to survive in niches previously unused by parental taxa (i.e., warmer thermal environments) without incurring intrinsic selection. 相似文献
6.
A genetic linkage map of tef [Eragrostis tef (Zucc.) Trotter] based on amplified fragment length polymorphism 总被引:2,自引:0,他引:2
G. Bai H. Tefera M. Ayele H. T. Nguyen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(3-4):599-604
A genetic linkage map of tef was constructed with amplified fragment length polymorphism (AFLP) markers using F5 recombinant inbred lines (RILs) derived by single seed descent from the intraspecific cross of ’Kaye Murri’×’Fesho’. A total
of 192 EcoRI/MseI primer combinations were screened for parental polymorphism. Around three polymorphic fragments per primer combination were
detected, indicating a low polymorphism level in tef. Fifty primer combinations were selected to assay the mapping population,
and 226 loci segregated among 85 F5 RILs. Most AFLP loci behaved as dominant markers (presence or absence of a band), but about 15% of the loci were codominant.
Significant deviations from the expected Mendelian segregation ratio were observed for 26 loci. The genetic linkage map comprised
211 markers assembled into 25 linkage groups and covered 2,149 cM of genome. AFLP is an efficient marker system for mapping
plant species with low polymorphism such as tef. This is the first genetic linkage map constructed for tef. It will facilitate
the mapping of genes controlling agronomically important traits and cultivar improvement in tef.
Received: 27 April 1998 / Accepted: 4 January 1999 相似文献
7.
QTL mapping for fiber quality traits across multiple generations and environments in upland cotton 总被引:12,自引:0,他引:12
Fu-Ding Sun Jian-Hong Zhang Shu-Fang Wang Wan-Kui Gong Yu-Zhen Shi Ai-Ying Liu Jun-Wen Li Ju-Wu Gong Hai-Hong Shang You-Lu Yuan 《Molecular breeding : new strategies in plant improvement》2012,30(1):569-582
Identification of quantitative trait loci (QTL) for fiber quality traits that are stable across multiple generations and environments could facilitate marker-assisted selection for improving cotton strains. In the present study, F2, F2:3, and recombinant inbred lines (RILs, F 6:8 ) populations derived from an upland cotton (Gossypium hirsutum L.) cross between strain 0-153, which has excellent fiber quality, and strain sGK9708, a commercial transgenic cultivar, were constructed for QTL tagging of fiber quality. We used 5,742 simple sequence repeat primer pairs to screen for polymorphisms between the two parent strains. Linkage maps of F2 and RILs were constructed, containing 155 and 190 loci and with a total map distance of 959.4 centimorgans (cM) and 700.9?cM, respectively. We screened fiber quality QTL across multiple generations and environments through composite interval mapping of fiber quality data. Specifically, we studied F2 and F2:3 family lines from Anyang (Henan Province) in 2003 and 2004 and RILs in Anyang in 2007 and Anyang, Quzhou (Hebei Province), and Linqing (Shandong Province) in 2008. We identified 50 QTL for fiber quality: 10 for fiber strength, 10 for fiber length, 10 for micronaire, eight for fiber uniformity, and 12 for fiber elongation. Nine of these fiber quality QTL were identified in F2, F2:3 and RILs simultaneously. Two QTL for fiber strength on chromosomes C7 and C25 were detected in all three generations and all four environments and explained 16.67?C27.86% and 9.43?C21.36% of the phenotypic variation, respectively. These stable QTL for fiber quality traits could be used for marker assisted selection. 相似文献
8.
Y. Naciri A. Gallais 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(6):693-697
Two-factor mating designs at consecutive Sn and S(n+1) levels (S0 and S1 S1 and S2, or F2 and F3) allow estimation of all components of the variation among homozygous lines and F1 hybrids that can be derived from a given population. They also allow for the prediction of the mean of these lines and single-cross hybrids. Some tests for the presence of epistasis are possible at the levels of means and of variances. Such mating designs can be very useful for predicting the value of the best possible lines or the best possible F1 hybrids when it is difficult to produce, at an experimental level for exploratory purposes, either lines or hybrids. 相似文献
9.
Analysis of transcriptional and epigenetic changes in hybrid vigor of allopolyploid Brassica napus uncovers key roles for small RNAs 下载免费PDF全文
Yifei Shen Shuo Sun Shuijin Hua Enhui Shen Chu‐Yu Ye Daguang Cai Michael P. Timko Qian‐Hao Zhu Longjiang Fan 《The Plant journal : for cell and molecular biology》2017,91(5):874-893
10.
Genetic mapping in maize with hybrid progeny across testers and generations: plant height and flowering 总被引:9,自引:0,他引:9
D. F. Austin M. Lee L. R. Veldboom 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(1):163-176
DNA markers were used to identify quantitative trait loci (QTLs) for plant height, ear height, and three flowering traits
in hybrid progeny of two generations (F2:3, F6:8) of lines from a Mo17×H99 maize population. For both generations, testcross (TC) progeny were developed by crossing the lines
to three inbred testers (B91, A632, B73). The hybrid progeny from the two generations were evaluated at the same locations
but in different years as per an early generation testing program. QTLs were identified within each TC population and for
mean testcross (MTC) performance. Overall, more QTLs were detected in the F6:8 than the F2:3 generation. Totalled over all five traits, 41 (B91) to 69% (B73) of the QTLs for tester effects and 67% of the QTLs for MTC
detected in the F2:3 generation were verified in the F6:8 generation. Although differences in relative rank of the QTL effects across generations were observed, especially for the
flowering traits, parental contributions were nearly always consistent. Several (8–11) QTLs were identified with effects for
all three tester populations and for all traits except the anthesis-silk interval, which had only two such regions. Over all
five traits, previous evaluations in this population identified 26 QTLs with consistent effects for two (F2:3, F6:8) inbred-progeny evaluations, and 20 (77%) were also associated with MTC in at least one of the generations evaluated herein.
In all instances of common inbred and TC QTLs, parental contributions were the same.
Received: 26 November 1999 / Accepted: 18 April 2000 相似文献
11.
P. Ajmone Marsan C. Gorni A. Chittò R. Redaelli R. van Vijk P. Stam M. Motto 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(2-3):230-243
We exploited the AFLP®1(AFLP® is a registered trademark of Keygene, N.V.) technique to map and characterise quantitative trait loci (QTLs) for grain yield and two grain-related traits of a maize segregating population. Two maize elite inbred lines were crossed to produce 229 F2 individuals which were genotyped with 66 RFLP and 246 AFLP marker loci. By selfing the F2 plants 229 F3 lines were produced and subsequently crossed to two inbred testers (T1 and T2). Each series of testcrosses was evaluated in field trials for grain yield, dry matter concentration, and test weight. The efficiency of generating AFLP markers was substantially higher relative to RFLP markers in the same population, and the speed at which they were generated showed a great potential for application in marker-assisted selection. AFLP markers covered linkage group regions left uncovered by RFLPs; in particular at telomeric regions, previously almost devoided of markers. This increase of genome coverage afforded by the inclusion of the AFLPs revealed new QTL locations for all the traits investigated and allowed us to map telomeric QTLs with higher precision. The present study has also provided an opportunity to compare simple (SIM) and composite interval mapping (CIM) for QTL analysis. Our results indicated that the method of CIM employed in this study has greater power in the detection of QTLs, and provided more precise and accurate estimates of QTL positions and effects than SIM. For all traits and both testers we detected a total of 36 QTLs, of which only two were in common between testers. This suggested that the choice of a tester for identifying QTL alleles for use in improving an inbred is critical and that the expression of QTL alleles identified may be tester-specific. 相似文献
12.
We examined six allozyme markers and shell morphology to study gene flow between the naturally sympatric freshwater snail species Viviparus ater and V. contectus in Lake Garda, Italy, using offspring from experimental crosses and snails collected from natural populations. Hybrid offspring obtained from experimental crosses and hybrids collected from natural populations were heterozygous at four or five out of five diagnostic loci. Shell morphology was a poor predictor of the hybrid status of individual snails. Backcrossed offspring from experimentally bred hybrids and either of the parental species morphologically resembled the parental species. There was no evidence of segregation distortion at the six loci. Linkage analysis revealed one pair of linked loci (GPI and PNP). These cross experiments indicated a Mendelian type hybrid system in which gene introgression may occur. F1 hybrids were found at four out of six sampling sites of Lake Garda, Italy. Local frequencies of F1 hybrids ranged from 0% to 1.6% (estimated average = 0.74%) of the total population including both species. Alleles typical of V. ater were found at low frequencies in V. contectus at all six sampling sites. Alleles typical of V. contectus were found at low frequencies in V. ater at three out of six sampling sites. This is consistent with the hypothesis of introgression in both directions. 相似文献
13.
To what extent is adaptive evolution over short timescales repeatable? To address this question, we studied the performance of crosses between replicate Drosophila melanogaster lines previously subject to selection for improved learning response in the context of oviposition substrate choice. Of the 10 pairwise F1 crosses among the five selection lines, four performed in the original learning assay similarly to the parental lines, whereas the remaining six showed learning scores significantly below the average of the parental lines. In particular, four F1 crosses (three involving the same line) showed no detectable learning, on a par with unselected control lines. This indicates that the response to selection in some lines involved allelic substitutions at different loci. Additional assays of crosses between two selection lines indicated that the loss of performance in hybrids generalized to another type of learning assay, and held for both short‐ and long‐term memory. Joint analysis of first‐ and second‐generation crosses between these two lines supported the hypothesis that the response to selection in these different lines was based on the spread of recessive alleles at different loci. These results show that the evolutionary trajectories of populations of the same origin subject to uniform selection may sometimes diverge over very short evolutionary timescales. 相似文献
14.
S. CARRÉ J. N. TASEI J. Le GUEN J. MESQUIDA G. MORIN 《The Annals of applied biology》1993,122(3):555-568
A simplified and non-destructive method using starch gel electrophoresis has been developed on seeds to identify inbred lines of Vicia faba and assess outcrossing rates and gene dispersal in pollination experiments. Six enzyme systems (Alcohol dehydrogenase, Aspartate aminotransferase, Glucose-6-phosphate isomerase, Isocitrate dehydrogenase, Phosphogluconate dehydrogenase and Shikimate dehydrogenase) were analysed from parental lines, crosses performed between lines bearing dissimilar isozyme patterns in pollination cages with Bombus and F2 progenies obtained from manual selfing of F1 hybrids. The allozymes at each of the seven studied loci segregated in the expected Mendelian fashion and behaved in a co-dominant manner except for the Adh-2 locus where the only variant was a null allele. No evidence of genetic linkage was observed between at least 13 of the 15 pairs of the studied loci. Percentage of cross fertilisation by Bombus between seven pairs of inbred lines ranged between 1.7% and 28.3%. Pollen transfer between a donor line and a recipient line by two species of Bombus did not lead to differences in outcrossing rates (both about 8%). The new PGD marker with two loci at three alleles each is particularly discriminating and valuable in pollination studies and breeding of V. faba. 相似文献
15.
Nannan Liu Yuanhao Du Marilyn L Warburton Yingjie Xiao Jianbing Yan 《Molecular biology and evolution》2021,38(4):1262
Plant phenotypic plasticity describes altered phenotypic performance of an individual when grown in different environments. Exploring genetic architecture underlying plant plasticity variation may help mitigate the detrimental effects of a rapidly changing climate on agriculture, but little research has been done in this area to date. In the present study, we established a population of 976 maize F1 hybrids by crossing 488 diverse inbred lines with two elite testers. Genome-wide association study identified hundreds of quantitative trait loci associated with phenotypic plasticity variation across diverse F1 hybrids, the majority of which contributed very little variance, in accordance with the polygenic nature of these traits. We identified several quantitative trait locus regions that may have been selected during the tropical-temperate adaptation process. We also observed heterosis in terms of phenotypic plasticity, in addition to the traditional genetic value differences measured between hybrid and inbred lines, and the pattern of which was affected by genetic background. Our results demonstrate a landscape of phenotypic plasticity in maize, which will aid in the understanding of its genetic architecture, its contribution to adaptation and heterosis, and how it may be exploited for future maize breeding in a rapidly changing environment. 相似文献
16.
C. P. Werner A. P. Setter B. M. Smith J. Kubba M. J. Kearsey 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,77(4):527-534
Summary Performance of a random array of recombinant inbred lines derived by single seed descent from five different source populations of Brussels sprouts (Brassica oleracea var. gemmifera) is presented. A total of 2,356 lines were tested in trials during 1985 and 1986. Three of the source populations were derived from double crosses between F1 hybrids. These hybrids show a considerable heterotic advantage over their inbred parents for the most important agronomic traits. The recombinant inbred lines performed, on average, less well than the parental inbred material, indicating that additive x additive genie interactions may make a significant contribution to the performance of current inbred material. Nevertheless, the very large variation among the recombinant inbred lines permitted many lines to be identified which outperformed the best parental inbred for all traits. Two lines outperformed the reference F1 hybrid, Gower, for an index that included marketable yield and quality. Consideration was also given to the dangers of misinterpreting phenotypically based proportions. Accordingly, response equations were used to ascertain the real genetic progress that was made. Advance seemed small when compared with the large heterotic effect, which is consistent with the segregation of a large number of loci. The distribution of the recombinant inbred lines was compared to predictions made from early generation trials. There was broad agreement but significant discrepancies existed which, it is suggested, may arise from the effects of genotype-environment interactions. 相似文献
17.
Singh SP Sundaram RM Biradar SK Ahmed MI Viraktamath BC Siddiq EA 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2006,113(3):509-517
Although pronounced heterosis in inter-subspecific hybrids was known in rice for a long time, its utilization for hybrid rice breeding has been limited due to their hybrid sterility (HS). For the last two decades, however, a few inter-subspecific hybrids have been developed by incorporating wide-compatibility genes (WCG) that resolve HS, into parental lines of these inter-subspecific hybrids. For effective use of WCG, it is necessary to find convenient markers linked to WCG of practical importance. In this paper, initially a set of simple sequence repeat (SSR) markers in the vicinity of known WCG loci identified based on comparative linkage maps have been surveyed in a population derived from the three-way cross- IR36/Dular//Akihikari, where a known donor of WCG Dular was crossed to a representative indica and japonica cultivar. Of the five parental polymorphic markers, RM253 and RM276 were found to be closely linked to the WCG locus S5 at a distance of 3.0 and 2.8 cM, respectively. Later, loci for HS were examined in three F2 populations derived from inter-subspecific crosses, with same set of SSR markers. The locus S8 was confirmed to have major influence on HS in the F2 population derived from CHMRF-1/Taichung65 since two SSR markers in its vicinity, RM412 and RM141, co-segregated with HS at a map distance of 7.6 and 4.8 cM, respectively. In the F2 population derived from the cross BPT5204/Taipei309, three SSR markers in the vicinity of S5, RM50, RM276 and RM136 co-segregated with HS at a map distance of 4.2, 3.2 and 7.8 cM, respectively. In the third F2 population derived from Swarna/Taipei309, the SSR markers in the vicinity of S5, RM225, RM253, RM50, RM276 and RM136 were identified to co-segregate with HS at a map distance of 3.2, 2.6, 3.4, 2.6 and 6.6 cM, respectively. These results indicated a clear picture of WCG in Dular as well as the predominant role of HS alleles at S5 locus. The identified SSR markers are expected to be used for incorporation of WCG into parental lines in hybrid rice breeding to solve HS in inter-subspecific hybrids.S.P. Singh , R.M. Sundaram contributed equally 相似文献
18.
SABINA L. MAHUAD GUILLERMO R. PRATTA GUSTAVO R. RODRIGUEZ ROXANA ZORZOLI LILIANA A. PICARDI 《Journal of genetics》2013,92(2):195-203
Five recombinant inbred lines obtained from the F2 generation of an interspecific cross between cultivar, Caimanta (Cai, Solanum lycopersicum) and wild accession, LA722 (P, S. pimpinellifolium) were crossed to obtain the second cycle hybrids (SCH). Eleven fruit quality traits were assessed in evaluating phenotypic variability among genotypes P, Cai, F1 (Cai × P), five RILs, and 10 SCH. One of the five recombinant inbred lines and three SCH had higher values than P, as the best genotype for shelf life. Sequence-related amplified polymorphism was used as the molecular method for detecting polymorphism among these 18 genotypes. The percentage of polymorphism in RILs and SCH was 61% and 66% respectively. Moreover, some bands detected in P were present in SCH. Several multivariate analyses were performed to find agreement between the phenotypic variability observed for fruit quality traits and the polymorphism obtained from sequence-related amplified polymorphism markers. A general Procrustes analysis estimated that there was a consensus proportion of 75% between phenotypic and molecular data. There was considerable preservation of some bands from the wild genotype, which could increase the variability in fruit quality traits in populations where the genetic diversity is limited. 相似文献
19.
Ronald S. Burton 《Evolution; international journal of organic evolution》1987,41(3):504-513
Geographically separated populations of the intertidal copepod Tigriopus californicus are sharply differentiated at several enzyme-encoding gene loci. Two studies were performed to investigate the extent to which the gene pools of local populations are organized into harmoniously interacting (or “coadapted”) gene complexes. In the first, the effects of interpopulation hybridization on development time were assessed. Results showed that while F1 hybrids did not differ from parental lines, mean F2 developmental times were as much as 50% longer. The second study used two unlinked enzyme polymorphisms as genetic markers to determine the genotypic specificity of F2 hybrid breakdown. For two sets of parental populations, the relative viabilities of the different two-locus genotypes were determined from segregation ratios among the F2 progeny. Sharp deviations from Mendelian ratios were observed; in the extreme, a block of genes marked by the MeF allozyme from the LJ (La Jolla) population was found to be nearly lethal when homozygous in the F2 of LJ × AB (Los Angeles) crosses. This same block of genes had a tenfold higher viability in crosses between LJ and SC (Santa Cruz). In the AB × LJ crosses, the two marker loci had independent (multiplicative) effects on viability. In the SC × LJ crosses, deviations from the multiplicative model were observed; the data indicate that parental homozygous genotypes have higher viability than predicted by independence, while nonparental homozygotes have lower than predicted viability. These results suggest that substantial integration of the genome has occurred within natural T. californicus populations. 相似文献
20.
Sarah J. Lehnert Oliver P. Love Trevor E. Pitcher Dennis M. Higgs Daniel D. Heath 《Genetica》2014,142(4):281-293
Outbreeding, mating between genetically divergent individuals, may result in negative fitness consequences for offspring via outbreeding depression. Outbreeding effects are of notable concern in salmonid research as outbreeding can have major implications for salmon aquaculture and conservation management. We therefore quantified outbreeding effects in two generations (F1 hybrids and F2 backcrossed hybrids) of Chinook salmon (Oncorhynchus tshawytscha) derived from captively-reared purebred lines that had been selectively bred for differential performance based on disease resistance and growth rate. Parental lines were crossed in 2009 to create purebred and reciprocal hybrid crosses (n = 53 families), and in 2010 parental and hybrid crosses were crossed to create purebred and backcrossed hybrid crosses (n = 66 families). Although we found significant genetic divergence between the parental lines (FST = 0.130), reciprocal F1 hybrids showed no evidence of outbreeding depression (hybrid breakdown) or favorable heterosis for weight, length, condition or survival. The F2 backcrossed hybrids showed no outbreeding depression for a suite of fitness related traits measured from egg to sexually mature adult life stages. Our study contributes to the current knowledge of outbreeding effects in salmonids and supports the need for more research to better comprehend the mechanisms driving outbreeding depression. 相似文献