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1.
The objectives of this study were to quantify the components of genetic variance and the genetic effects, and to examine the
genetic relationship of inbred lines extracted from various shrunken2 (sh2) breeding populations. Ten diverse inbred lines developed from sh2 genetic background, were crossed in half diallel. Parents and their F1 hybrids were evaluated at three environments. The
parents were genotyped using 20 polymorphic simple sequence repeats (SSR). Agronomic and quality traits were analysed by a
mixed linear model according to additive-dominance genetic model. Genetic effects were estimated using an adjusted unbiased
prediction method. Additive variance was more important than dominance variance in the expression of traits related to ear
aspects (husk ratio and percentage of ear filled) and eating quality (flavour and total soluble solids). For agronomic traits,
however, dominance variance was more important than additive variance. The additive genetic correlation between flavour and
tenderness was strong (r = 0.84, P < 0.01). Flavour, tenderness and kernel colour additive genetic effects were not correlated with yield related traits. Genetic
distance (GD), estimated from SSR profiles on the basis of Jaccard’s similarity coefficient varied from 0.10 to 0.77 with
an average of 0.56. Cluster analysis classified parents according to their pedigree relationships. In most studied traits,
F1 performance was not associated with GD. 相似文献
2.
Expression of additive and dominance effects during development of forest trees species is poorly documented. A set of 10
subpopulations, generated from factorial mating amongst subsets of 88 females and 107 males representing 684 families and
37,206 individual trees, was used to estimate variance components between 4 and 65 months in a Eucalyptus urophylla * grandis breeding population. The variance components were significantly different from zero for female, male and female-by-male interaction
effects for height and circumference. The results, from the set of experiments, stressed the huge dispersion of variance component
estimates among subpopulations. The trends were modelled using linear and nonlinear models. The trends in additive, dominance
and environmental variances with age showed three phases corresponding to the stage of competition during stand development.
No significant trend was observed for the coefficients of variation of these three effects. The dominance to additive variance
ratio did not show specific age-related trends and was close to 1.2 during the growth period. The additive, dominance and
environmental correlations between height and circumference were higher than 0.8 after 24 months. A similar age-related trend
was observed for the additive and dominance effects. These results emphasise the significant role of dominance in the genetic
control of growth traits. They differ from the majority of studies of pines, where additive variance is preponderant, but
are similar to those of other eucalyptus studies. In the context of Congolese breeding strategy, this can be explained by
the phenotypic selection of parents constituting the breeding population and/or the expression of overdominance in eucalyptus
hybrid populations planted in marginal zones. 相似文献
3.
M. N. Barakat 《Euphytica》1996,87(2):119-125
Summary Estimates of gene actions were obtained for five in vitro traits of immature wheat (Triticum aestivum L.) embryo cultures from a cross of two wheat cultivars and the resulting reciprocal, F1, F2 and backcross populations. The contribution of additive gene effects to in vitro traits was not as important as the dominance gene effects. Epistatic gene effects were relatively more important than either additive or dominance gene effects. Of the individual types of digenic epistatic effects, the dominance x dominance estimates were relatively larger in magnitude for all in vitro culture traits measured. The maternal effect played a minor role in the inheritance of the in vitro studied traits since the difference among the reciprocal values was not significant. It is shown from the generation mean method that epistasis played a major role in the inheritance of most of the traits under study. The negative values of additive and dominance genetic variance were estimates of zero. Heritability estimates, in broad sense, were relatively high for the in vitro studied traits. In some cases, heritability estimates in broad and narrow senses are almost equal since the estimation of dominance genetic variance led to negative values. According to the results of the gene effects, dominance and epistasis were important for the shoot formation trait. Selection would be effective among the isolated genotypes on individual basis. 相似文献
4.
Germplasm for genetic improvement of lint yield in Upland cotton: genetic analysis of lint yield with yield components 总被引：1，自引：0，他引：1
Determination of genetic effects for lint yield and yield components in cotton (Gossypium hirsutum L.) germplasm is critical for its utilization in breeding programs. This study was designed to apply the conditional approach and an additive and dominant model to analyze genetic effects for lint yield and yield components. Forty-eight F2 populations derived from crosses between four existent Upland cotton cultivars as female parents and 12 germplasm lines as male parents were evaluated at two locations in 2008 and 2009. Conditional and unconditional variance components were estimated by the mixed linear model based conditional approach. Lint yield and yield components were mainly controlled by genotypic effects, i.e., additive variance and dominance variance (≥66 % of total phenotypic variation). Lint percentage and lint index had the highest proportions of additive variance component to the total phenotypic variances. SP156 and SP205 had positive additive effects for lint yield and yield components, and were also parents of the most hybrids with positive predicted dominant effects. Therefore, these two lines are good combiners for development of both pure lines and hybrids. Positive additive contribution effects to lint yield from lint percentage, boll number, boll weight, and seed index were detected in different parents. Adding seed index to boll number and lint percentage increased additive contribution effects to lint yield from these two components relative to the contribution effects from either boll number or lint percentage alone. Results in this study suggest that boll number, lint percentage, and seed index should be balanced in pure line development. 相似文献
5.
Summary Triple test cross-analysis was used to detect epistasis in chickpea. None of the characters investigated exhibited epistasis. In the absence of epistasis, additive and dominance effects were estimated. The results indicated the importance of additive genetic variance for seed yield, biological yield, number of primary branches, number of secondary branches, 100-seed weight, days to flower, and number of seeds per pod; dominance genetic variance for days to mature; and both additive and dominance genetic variances for plant height. Selection methods, such as pedigree and bulk, are suggested for the improvement of most characters.Joint contribution from ICARDA, P.O. Box 5466, Aleppo, Syria and ICRISAT (International Crops Research Institute for the Semi-Arid Tropics), Patancheru P.O. 502 324, A.P., India. 相似文献
6.
Summary Three lentil (Lens culinaris
Medic) crosses (cross 1 = Chilean × PI 297784; cross 2 = Tekoa × PI 212611; cross 3 = Precoz × PI 212611) were advanced in a hierarchal design from the F2 generation to the F5 generation and tested in replicated field experiments. The purpose was to estimate the genotypic variances and covariances for several characters and to partition these into components due to additive, dominance, and additive × additive variances.Additive genetic variance was the major component of variance in cross 2 for all characters, except plant height and seed weight. Unexpectedly, estimates of dominance variance appeared to be high in crosses 1 and 3. Estimates of the additive × additive component seemed very small in all three populations. The dominance variance component estimates were consistently high for plant height in the three crosses and for seed weight in crosses 2 and 3. Where parental means were close, additive variance estimates were often low and in many cases negative. The unexpected high ratio of dominance variance to additive variance indicated that dominance variance was important in the crosses we studied.Cooperative investigations of Agricultural Research Service, US Department of Agriculture and the College of Agriculture, Washington State University, Pullman, Washington 99164, Work sponsored by Fellowship from Univ. of Jordan, Amman, Jordan. Scientific paper no. 5825.Formerly: Department of Agronomy and Soils, Washington State University, Pullman, WA., USA. Presently: Department of Plant Production and Plant Protection, University of Jordan, Amman, Jordan.Statistical Services, Washington State University, Pullman, WA 99164, USA.US Department of Agriculture, Agricultural Research Service, Washington State University, Pullman WA 99164, USA. 相似文献
7.
M. R. Simón 《Euphytica》1994,76(3):235-238
Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5
th
leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC1 and BC2).Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5
th
leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity. 相似文献
8.
Summary Heritabilities and responses to selection for cut flower yield were estimated for a population of gerbera. Broad-sense heritabilities averaged 42 percent, but may be as high as 66 percent. Narrow sense heritabilities averaged 68 percent when based on half-sib families, and averaged 60 percent when based on parent-offspring regression. These results suggest that most genetic variance for flower yield is additive.However, estimates of realized heritability averaged only 16 percent and inbreeding depression was estimated to be at least 38 percent, suggesting a major role for non-additive genetic variance. Nonetheless, selection for cut flower yield is expected to be successful. 相似文献
9.
Gene effects of resistance to two isolates of Phytophthora
nicotianae in two crosses of pepper were investigated using separate generation means analysis. Additive-dominance models were inadequate
in all cases. Digenic parameter models were adequate in three cases and the probability of goodness of fit of models was negatively
correlated with the aggressiveness of the pathogen. None of these models explained variation among generation means in the
combined cross Beldi × CM334 with P.
nicotianae isolate Pn2. Additive × additive, dominance × dominance and dominance × additive effects were significant in most cases. Additive and
dominance effects (of negative sign) contribute more to resistance than to susceptibility. Additive variance was greater than
environmental and dominance variance and ranged from 0.038 to 0.224. Narrow-sense heritabilities were dependent upon the cross
and inoculate and ranged from 86 to 92%. The results of this study indicate that selection with more aggressive isolates of
the pathogen will be useful for enhancing resistance in pepper. 相似文献
10.
Summary Crosses were made between the highly susceptible Little Club and the partially resistant cultivars Westphal 12A, Akabozu and BH 1146 to obtain F1, F2 and backcross generations. Latency period (LP) was determined in plants inoculated at the young flag leaf stage with a monospore culture of race Flamingo of wheat leaf rust. Broad sense heritability of LP in the F2 averaged 0.8. The genes showed partial to almost complete recessive inheritance. Scaling tests indicated that additive gene action was the most important factor in the inheritance of partial resistance. The tests showed that there were no indications for additive x additive, additive x dominance or dominance x dominance interactions. The number of effective factors was estimated as one or two for Akabozu, three or more for Westphal 12A, and two or three for BH 1146. BH 1146 also possessed a (semi-)dominant gene for a lower infection type which was temperature sensitive in its expression. The genes of the various parents had unequal effect on LP. 相似文献
11.
The inheritance of resistance to head blight caused by Fusarium culmorum in winter wheat 总被引：8，自引：0，他引：8
C.H.A. Snijders 《Euphytica》1990,50(1):11-18
Summary Crosses were made among ten winter wheat genotypes representing different levels of resistance to Fusarium head blight to obtain F1 and F2 generations. Parents, F1 and F2 were inoculated with one strain of Fusarium culmorum. Data on incidence of head blight 21 days after first inoculation were analyzed. Broad-sense heritabilities averaged 0.39 and ranged from 0.05 to 0.89 in the individual F2 families. The joint-scaling test indicated that the inheritance of Fusarium head blight resistance was adequately described by the additive-dominance model, with additive gene action being the most important factor of resistance. With respect to the non-additive effects, dominance of resistance predominated over recessiveness. The number of segregating genes governing resistance in the studied populations was estimated to vary between one and six. It was demonstrated that resistance genes differed between parents and affected resistance differently. 相似文献
12.
Thirty bi-parental progenies were generated using 45 genotypes from the University of California (UC) strawberry breeding
population as parents. Both parent genotypes and their offspring were classified for photoperiod insensitivity, or day-neutrality,
for flowering using a late-season flowering score and the number of inflorescences per plant recorded during late summer.
Complex Segregation Analysis of these traits indicated that their distributions were best explained by a genetic model that
postulates a single major locus with partial dominance for day-neutrality in combination with a background of polygenic and
environmental variation. The frequency of the allele conferring day-neutrality was estimated as p = 0.59–0.62 in this experimental population. Genotypic values for the inferred major locus were estimated as a = 1.12 and d = −0.81 for the flowering score, and a = 4.93 and d = 2.41 for inflorescence number. Further resolution of inheritance patterns were obtained by comparing the phenotypic variance
for each trait with estimates obtained by insertion of these genotypic class values and allele frequencies into standard quantitative
genetic models, and by the comparing variance components estimated using a mixed model analysis with and without inferred
genotypic classes as a fixed effect. These comparisons suggest that the major gene determines 80.5% and 73.9% of the additive
genetic variance for flowering score and inflorescence number respectively. One complicating feature of the results obtained
here is that a non-Mendelian model of segregation fit statistically better than a fixed Mendelian model. The genetic parameters
estimated using this non-Mendelian model were essentially identical to those obtained with fixed segregation; hybrid and octoploid
ancestry, selection affecting flowering response, and limited number of generations in the analysis are discussed as possible
explanations of this result. 相似文献
13.
Inheritance of resistance to yellowberry in durum wheat 总被引：1，自引：1，他引：0
Resistance to grain yellowberry in durum wheat (Triticum durum Desf.) was investigated using generation mean analysis in four resistant or intermediate-resistant X susceptible crosses.
Significant differences in resistance were observed between generations in all crosses. Generation mean analysis indicated
a complex gene action controlling this trait, with additive, dominance and epistatic effects. Additive (d) components were
positive in all crosses, suggesting that additive effects contributed more to resistance than to susceptibility. In contrast
dominance (h) effects were negative in majority of crosses. The minimum number of genes controlling resistance was estimated
at 1.41. Mid-parent heterosis ranged from 28.5 to 52.1 indicating dominance of resistance. Broad-sense heritability estimates
ranged from 0.52 to 0.88, while narrow-sense heritability estimates ranged from 0 to 0.79. Estimates of genetic gain for resistance
ranged from low to high. Estimates of broad and narrow sense heritabilities indicated that genetic effects were larger than
environmental effects. Additive effects represented the largest components of genetic effects. 相似文献
14.
Pham X. Tung 《Euphytica》1992,61(1):73-80
Summary Genetic variance components and heritability were estimated for resistance to bacterial wilt in a population of tetraploid potato with resistance derived from several specific sources. Both additive and non-additive variance components were significant. Their relative magnitudes indicated the importance of non-additive gene action in the genetic control of the resistance. Narrow-sense heritability was relatively low for both disease index and % survival indicating that progress in population development would be slow. Broad-sense heritability was, however, relatively high which promises success of clonal selection in developing clonal resistant cultivars. 相似文献
15.
Inheritance of yield and yield contributing characters were investigated using generation mean analysis, utilising the means
of six basic populations viz., P1, P2, F1, F2, BC1P1 and BC1P2 in four crosses of Vigna sesquipedalis. The analysis reiterated that the importance of dominance (h) gene effects for pod yield/plant and pods/plant as compared
to additive (d) gene effects. However, significant and positive additive effects were noticed for pod yield/plant, pods/plant,
pod weight and seed weight in different crosses. The three types of gene interactions (additive, dominance and epistasis)
were significantly involved for pods/plant in cross KU 7 ×KU 8. Among the digenic epistatic interactions, both additive ×additive
(i) and dominance × dominance (l) contributed more for pod yield/plant and pods/plant, however, it varied among the crosses.
Populations having earliness can be developed as indicated by reducing dominance effects. Pedigree selection and heterosis
breeding is suggested to exploit the fixable and non fixable components of variation respectively in Vigna sesquipedalis.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
陆地棉产量性状的遗传分析 总被引：22，自引：0，他引：22
采用加性-显性与环境互作的遗传模型,分析陆地棉8个杂交亲本和F128个组合的7个产量性状的两年试验资料,估算各项遗传方并非分量和F1、F2的杂种优势.结果表明,产量性状受加性效应和显性效应共同控制,加性×环境各产量性状均极显著,铃重、衣分、籽指还受显性×环境的极显著影响,7项产量性状的广义和狭义遗传率均达到极显著水准. 相似文献
17.
Knowledge of genetic relationships between within‐boll yield components and fibre quality is essential for simultaneous improvement of lint yield and fibre quality in upland cotton (Gossypium hirsutum L.). Nine parents and their F1 progeny with reciprocals from a 3 × 6 factorial mating design were grown in 2008 and 2009. Seven within‐boll yield components and two boll morphological traits and the three fibre quality parameters were analysed based on a conditional additive/dominance (AD) genetic model. Results showed that boll length contributed to the largest proportion of phenotypic, additive and dominance variances for UHM length; seed index contributed to the largest proportion of phenotypic and additive variances for fibre strength; boll width made the largest contribution to phenotypic and additive variances and the second largest contribution to dominance‐by‐environment interaction variance for micronaire, indicating that they played an important role than the other traits for fibre length, strength and fineness/maturity, respectively. It is worthy of note that those correlations between boll shape and fibre quality apply only to the nine parents and the resultant hybrids in this study and do not imply a cause and effect relationship. 相似文献
18.
Summary Breeding to improve stem strength is a major objective of researchers of sunflower (Helianthus annuus L.). This study was undertaken to investigate genetic factors controlling reduced plant height and increased stem diameter in three sources of sunflower, DDR, Donsky, and Donskoi 47, crossed with a conventional height line, HA 89. As these two characters may lead to improved standability, knowledge of their inheritance will assist researchers in utilizing proper breeding methods. Estimates of additive, dominance, and epistatic genetic effects controlling reduced height indicated that the additive component was most important in two of the three crosses with the additive and epistatic component nearly equal in the third cross. Breeding efforts to reduce height of sunflower hybrids utilizing these lines in crosses could be effective due to the magnitude of additive effects. The dominance component of genetic effects controlling stem diameter was the most important for two crosses, with both dominance and additive components important for the third cross. Epistasis was present, but minor, for controlling stem diameter. The high relative importance of the dominance component indicates that testcross evaluation of lines in early generations could identify lines for producing increased stem diameter in hybrids. Even though the three sources of sunflower with reduced height were different in morphologic and agronomic characteristics, they had similar genetic control of plant height and stem diameter. Each could be utilized in a breeding program to develop lines with reduced height and larger stem diameter. 相似文献
19.
Heritabilities for each of three different height and width ratios describing fruit shape were estimated from measurements
on a population of seedlings comprising 17 families of European and Asian pear parentage in the Hort Research pear cultivar
breeding programme. In families with European cultivars as parents, the pyriform curvature in the upper, or stem end, half
of the fruit was also quantified and heritabilities estimated. Heritabilities were computed using parent-offspring regression
and from consideration of the variance components. Heritabilities estimated from parent-offspring regression were generally
high and higher than those estimated from variance component analysis, although within the limits of error. Heritability estimates
for the height: maximum width ratio were > 0.5 by both methods of estimation indicating that fairly rapid genetic gain could
be expected.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
A series of half-diallel crosses involving early, medium and late maturity desi and kabuli type chickpea (Cicer arietinum L.) genotypes with stable resistance to Helicoverpa pod borer, along with the parents, were evaluated at two locations in India to understand the inheritance of pod borer resistance
and grain yield. Inheritance of resistance to pod borer and grain yield was different in desi and kabuli types. In desi type chickpea, the additive component of genetic variance was important in early maturity and dominance component was predominant
in medium maturity group, while in the late maturity group, additive as well as dominance components were equally important
in the inheritance of pod borer resistance. Both dominant and recessive genes conferring pod borer resistance seemed equally
frequent in the desi type parental lines of medium maturity group. However, dominant genes were in overall excess in the parents of early and
late maturity groups. In the kabuli medium maturity group, parents appeared to be genetically similar, possibly due to dispersion of genes conferring pod borer
resistance and susceptibility, while their F1s were significantly different for pod borer damage. The association of genes conferring pod borer resistance and susceptibility
in the parents could be attributed to the similarity of parents as well as their F1s for pod borer damage in kabuli early and late maturity groups. Grain yield was predominantly under the control of dominant gene action irrespective of the
maturity groups in desi chickpea. In all the maturity groups, dominant and recessive genes were in equal frequency among the desi parental lines. Dominant genes, which tend to increase or decrease grain yield are more or less present in equal frequency
in parents of the early maturity group, while in medium and late maturity groups, they were comparatively in unequal frequency
in desi type. Unlike in desi chickpea, differential patterns of genetic components were observed in kabuli chickpea. While the dominant genetic component was important in early and late maturity group, additive gene action was involved
in the inheritance of grain yield in medium duration group in kabuli chickpea. The dominant and recessive genes controlling grain yield are asymmetrically distributed in early and medium maturity
groups in kabuli chickpea. The implications of the inheritance pattern of pod borer resistance and grain yield are discussed in the context
of strategies to enhance pod borer resistance and grain yield in desi and kabuli chickpea cultivars. 相似文献