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1.
Summary The frequency and magnitude of heterosis were examined in relation to genetic divergence among parents in two diallel cross experiments in groundnut. The parents were grouped into clusters based on their diver-gence. The range, mean and standard deviation of the intra-and inter-cluster divergence were used to define four divergence classes. The frequency of heterotic crosses and the magnitude of heterosis for yield and its components were found to be higher in crosses between the parents in intermediate divergence classes than extreme ones. The results agreed well with the overall status of the specific combining ability of these crosses. 相似文献
2.
Heathcliffe Riday E. Charles Brummer T. Austin Campbell Diane Luth Patricia M. Cazcarro 《Euphytica》2003,131(1):37-45
Biomass yield heterosis has been shown to exist between Medicago sativasubsp. sativa and Medica gosativa subsp. falcata. The objective of this study was to gain a better understanding of what morphological and genetic factors were most highly
correlated with total biomass yield heterosis. We calculated genetic distances among nine sativa and five falcate genotypes
based on amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) DNA markers. Genetic distance did
not correlate with specific combining ability (SCA) or mid-parent heterosis. In contrast, a morphological distance matrix
based on seventeen agronomic and forage quality traits was significantly correlated with heterosis; the agronomic traits of
maturity, midseason regrowth, and autumn regrowth showed strong association with heterosis. Heterosis was also correlated
with subspecies. We suggest that in many cases progeny heterosis can be accounted for by the interaction of genes controlling
morphologically divergent traits between the parents. In other cases, progeny heterosis could also be due to divergence between
the parents at particular genetic loci that do not control field-level phenotypic differences. Genetic distanceper se between parental genotypes, based on neutral molecular markers, however, does not reflect the potential of individual genotypes
to produce heterosis in their progeny.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
3.
M. Maris 《Euphytica》1989,41(1-2):163-182
Summary The main aim of the experiment was to study the behaviour of seven long-day adapted clones of Solanum tuberosum ssp. andigena (A) and three varieties of S. tuberosum ssp. tuberosum (T) in an incomplete diallel cross. The four groups of crosses, TxT, TxA, AxT and AxA, held 2, 12, 20 and 21 populations, respectively. Eleven of the intersubspecific crosses were exact reciprocals. Thirty random clones per population were grown as second clonal generation in an incomplete block design with four replications in plots of two plants per clone in 1980, the parents included in many plots. Data were recorded on ten characters.The results showed that group TxA gave the highest tuber yield and AxT the second highest. The F-values indicated highly significant genotypic effects for all characters in all populations. The mean genotypic coefficients of variation (GCV), were the highest for group AxA for all characters. The ANOVA, based on population means showed significant mean squares for general combining abilities (GCA) and for differences of reciprocalls for all characters; the specific combining ability (SCA) mean squares were significant only for date of emergence, plant height and haulm type. Almost all GCA effects of the parents were significant positive or negative. Several populations showed also significant SCA effects. The correlations between the GCA effects and the parental values were of about the same magnitude as the heritabilities; those between the population means and the midparental values were slightly lower.Compared to the midparental values, most populations showed significant positive heterosis for date of emergence, haulm type, number of tubers and under water weight; all populations had significant negative heterosis for mean tuber weight and nearly all for plant height and general impression. All populations from groups TxT and AxA had significant negative heterosis for tuber yield and so had 13 out of the 20 populations from group AxT, while seven of the 12 from group TxA showed significant positive and four significant negative heterosis. The average heterosis for tuber yield of group TxT was –11%, of TxA 3.4%, of AxT–9% and of AxA–18%. The highest mean tuber yields were obtained from crosses with a very high yielding A-parent as female, while the heterosis was negative. Though significant differences between the 11 reciprocals occurred for all characters, consistent differences occurred only for tuber yield. Averaged over the 11 crosses the TxA populations outyielded their exact reciprocals by 10.7%. For the highest tuber yields in A-T crosses, therefore, the tuberosum cytoplasm seems to be preferable. By contrast for a high male fertility the andigena cytoplasm is preferable. 相似文献
4.
Ângela de Fátima Barbosa Abreu Magno Antonio Patto Ramalho Daniel Furtado Ferreira 《Euphytica》1999,108(2):121-127
Common bean populations from crosses between lines of different races are thought to be more promising for selection of high
yield potential than those from intra-racial crosses. Three distinct diallel crosses were made to test this hypothesis and
to determine the possibility of substituting diallel crosses for multivariate techniques that estimate genetic divergence.
The crosses were between races Mesoamerica × Mesoamerica, Mesoamerica × Durango and Jalisco, and Mesoamerica × Nueva Granada.
The parents and the resulting F4 populations were evaluated at Lavras-MG, Lambari-MG and Patos de Minas-MG, Brazil. The diallel analysis of seed yield was
done and the genetic divergence estimated by Mahalanobis distance. Estimates of general and specific combining ability indicated
that some inter-racial populations were more promising for selection to increase seed yield than intra-racial populations.
However, due to their undesirable seed color and size, and growth habit, especially in a short term breeding program, the
chances of obtaining high yielding lines with an acceptable bean is reduced. Genetic divergence was not a good measure to
choose the parents because usually, the most divergent groups included were not adapted lines.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
A partial diallel set of crosses was made between 14 potato cultivars chosen for their fertility, from those included in a potato breeding programme at the NEIKER – Basque Institute for Agricultural Research. The progeny were grown in completely randomized trials from 1997 to 1999. Performance for yield, tuber number and average tuber weight was analysed in seedling and two clonal generations. Variance estimates due to both general combining ability (GCA) and specific combining ability (SCA) were significant in all generations for all traits under study. However, SCA was more important than GCA in almost all cases. Correlation coefficients among characters, generations, GCA and SCA effects were examined. For tuber yield no relation was obtained between generations; however, average tuber weight and yield were positively associated in all generations. The results indicate that appropriate selection criteria depend strongly on the particular cross. The implication for a breeding strategy are discussed. 相似文献
6.
Summary Seven Solanum tuberosum ssp. tuberosum and three Solanum tuberosum ssp. andigena accessions were crossed to produce 12 Tuberosum × Tuberosum (T × T) and 9 Tuberosum × Andigena (T × A) progenies. These families were evaluated for five important traits for two successive clonal generations under short day sub-tropical plains. The differences in yield, average tuber weight and tuber number between {T × T }and T × A families in an early (75 days) crop were not significant. Compared to conventional intra-Tuberosum families, T × A families had significantly higher % tuber dry matter and specific gravity. In contrast to intra-Tuberosum crosses, T × A crosses exhibited a positive heterosis for tuber yield. Compared to T × T families, T × A families showed significantly higher heterosis for yield and tuber number. Comparison of T × T and T × A families and parents using canonical analysis led to the identification of superior hybrid families and superior parents. Some T × A progenies were close to breeding goal and thus can be used for selecting high-yielding cultivars. This revealed the usefulness of Andigena genotypes as parents in developing early bulking potato cultivars with broad genetic base for short day sub-tropical plains. 相似文献
7.
黄淮地区大豆重要亲本间产量的杂种优势、配合力及其遗传基础 总被引：8，自引：2，他引：6
2003-2005年以选自黄淮地区及美国的8个大豆重要亲本品种(系)及其组配的28个双列杂交组合为材料, 分析大豆亲本间的产量杂种优势及其配合力, 探讨高优势组合的遗传基础, 包括杂种优势与亲本系数、SSR标记遗传距离的相关。结果表明: (1)黄淮地区大豆亲本间存在产量超亲优势, 平均20.39%, 组合间差异甚大, 变幅–5.34%~76.88%, 优选出豫豆22×晋豆27、淮豆4号×晋豆27、诱变30×蒙90-24, 超亲优势分别为76.88%、29.90%和34.42%, 超标率均在25.00%以上, 晋豆27和诱变30为优秀亲本材料。单株荚数及单株粒数的优势和产量优势相对一致;(2) 大豆亲本间产量杂种优势既与双亲一般配合力之和及特殊配合力有关, 又不完全相关。高优势高产组合的亲本产量配合力特点为亲本之一具有较高的一般配合力, 或双亲具有较高的一般配合力之和, 兼有较高的特殊配合力。单株荚数和单株粒数的情况和产量一致;(3) 按亲本系数聚类和按SSR标记遗传相似系数聚类揭示的8个亲本间的遗传关系相对一致, 均分为两组, 一组包含6个黄淮中、南部品种(系), 另一组包含1个山西和1个美国品种。要获得高优势高产组合, 亲本间必须具有一定的遗传距离, 但遗传距离大并不一定都高产高优势, 还有其他因素决定杂种优势。 相似文献
8.
A. M. M. Barbosa I. O. Geraldi L. L. Benchimol A. A. F. Garcia C. L. Souza Jr. A. P. Souza 《Euphytica》2003,130(1):87-99
Two sets of tropical maize inbred lines, one derived from the BR-105 population and another derived from the BR-106 population,
were assayed for Amplified Fragment Length Polymorphism's (AFLP) and for Simple Sequence Repeat (SSR), in order to investigate
genetic distances among lines and their relationship to heterotic group assignment and single cross yield performance. Genetic
distances were on average greater for interpopulation than intrapopulation crosses for both AFLP and SSR. Cluster analysis
was in agreement with the original assignment for heterotic groups. Inbred line 16, derived from BR-106, was assigned to the
BR-105 set, in agreement with single cross yield performance from intra- and interpopulation crosses. However, the same pattern
was not observed for SSR where another two lines from BR-106 were also assigned to the BR-105 set. Correlation coefficients
of genetic distances (GD) with F1 grain yield and heterosis were high for BR-106 ×BR-106 crosses
(0.91** and 0.82** for AFLP and SSR, respectively), moderate for BR-105 × BR-105 crosses (0.52* for AFLP and SSR) and low for BR-105 × BR-106 crosses (0.29 and 0.16 for AFLP and SSR, respectively). The lower correlation
at interpopulation level was due to the smaller range of GD caused probably by a previous selection for combining ability.
General results showed that the AFLP molecular marker is efficient in assigning maize lines to heterotic groups and that AFLP-based
GD is suitable for predicting the maize single cross performance for intrapopulation crosses of broad-based populations. The
efficiency of SSR in assigning lines to heterotic groups and for predicting single cross performance was smaller than AFLP.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Diallel crosses have been widely used for analysis of general combining ability (GCA), specific combining ability (SCA) and heterosis. In the present research, 12 lines were selected from 60 inbred rice bred by International Rice Research Institute with extremely-high or -low yielding records according to the previous three consecutive seasons of yield trial experiments, to construct a half diallel cross. The genetic distances (GDs) revealed by molecular markers for the 12 lines ranged from 0.2288 to 0.7169, averaging at 0.5882; clustering analysis showed the 12 lines were divided into four groups maintaining the original cluster structure of the 60 lines. The positive loci (PLs) including effective-increasing loci (ILs) and effective-decreasing loci (DLs) were screened. The results showed that hybrids derived from those parents with higher GCA effects had better performance for traits of yield and yield components. The SCA effects were strongly correlated to F1 performance as well as heterosis; the GDs based on ILs were significantly positive correlated to SCA effects and heterosis for yield and yield components while the GDs based on DLs showed the significant negative correlations. Based on this research, a new conception, i.e. general sum of combining ability (GSCA) was conceived, which is defined as the sum of GCAs for two parents of a hybrid. The GSCA and SCA showed similar correlations with traits of yield and yield components. The results illustrated that ILs could be used for further study on prediction of heterosis for traits of yield and yield components; and GSCA may be another considerable parameter combined with ILs for breeders in selecting elite hybrid. 相似文献
10.
The aim of this study was to determine the direction and magnitude of change in morphological and agronomical characters of spring barley ( Hordeum vulgare L.) in Germany over a period of 80 years and to assess the value of various strategies for further crop improvement. Old and new two-rowed cultivars, eight in each case, were tested together with their F2 intra-group diallel crosses in a field trial at Braunschweig-Völkenrode in 1994. New parents and their crosses showed a higher dry matter grain and total biomass yield, a lower plant height, and a higher harvest index as compared to the respective old germplasm. The annual genetic gain in grain yield was estimated at 0.15%. The superior grain yield of the new germplasm was attributable to the higher number of ears per plant and the larger kernel weight. The F2 mid-parent heterosis in grain yield was 7.6 and 7.2 % for the old and new crosses, respectively. The differences between the two types of crosses were nonsignificant except for the higher heterosis for plant height in the new crosses. General combining ability effects were significant for all characters in both types of crosses, whereas specific combining ability effects were significant in a few cases only. In the new crosses, a significant positive correlation was found between grain yield and straw yield (r = 0.52), whereas no such association was observed between grain yield and harvest index. For further gain in grain yield, improvement of the straw yield is more promising than increasing harvest index. 相似文献
11.
爆裂玉米距离分析与杂种优势 总被引：19，自引：0，他引：19
根据80个爆裂玉米自交系数量性状的表现估算了它们之间的遗传距离，又估算了由其中49个自交系间随机组配的67个杂交组合F1代小区产量、爆粒率和膨胀倍数的杂种优势。相关和回归分析表明，F1代产量的对照优势与其双亲间的遗传距离呈显著的二次曲线关系，而F1代品质特性爆粒率和膨胀倍数的对照优势与其双亲之间的遗传距离无确定 相似文献
12.
Test‐crosses for estimating combining ability in potato although useful are difficult to make being labour intensive and time consuming, and due to the problem of sterility. The objective of the present study was to test methods for estimating general combining ability (GCA) of parents based on fewer matings. The GCA of 12 females estimated based on matings with specific single testers (top‐cross) and three types of bulk pollen (poly‐cross) were compared with those estimated by 72 (12 × 6) test‐crosses, using common testers in three types of matings. The study was conducted for 2 years at each of the two locations representing short‐days subtropical conditions in plains and long‐days temperate conditions in hills of India. Analysis of variance of test‐crosses showed that both general and specific combining ability effects were important for tuber yield, late blight resistance as well as general impression, the characters studied. Correlation coefficients among three types of matings showed that bulk pollen matings had poor effectiveness in predicting the GCA of the females, whereas matings with selected individual testers resulted in GCA estimates similar to those based on six testers. Thus use of top‐cross involving selected tester could substantially reduce the number of matings required for estimating the GCA. Among the six testers used, the tester CFK69.1 could estimate the GCA of the females with reasonably high accuracy both for tuber yield and general impression, and ‘Tobique’ for reaction to late blight. 相似文献
13.
S.-J. Kwon W.-G. Ha H.-G. Hwang S.-J. Yang H.-C. Choi H.-P. Moon S.-N. Ahn 《Plant Breeding》2002,121(6):487-492
Improving grain yield and quality of ‘Tongil’‐type rice (indica/japonica) continues to be a major breeding objective in Korea. In this study, genetic divergence among 13‘Tongil’‐type rice cultivars was evaluated and the relationship between genetic distance and hybrid performance in all possible nonreciprocal crosses between them assessed. The 78 F1 hybrids together with the 13 parents were evaluated for eight traits of agronomic importance, including yield, in a replicated field trial. The 13 parents were examined for DNA polymorphism using 71 micro‐satellite or simple sequence repeats and 46 random decamer oligonucleotide primers. A total of 319 polymorphic variants were generated and, based on the polymorphism data, genetic distances (GDs) ranged from 0.021 to 0.437. Cluster analysis based on GDs revealed associations among cultivars which was in agreement with the pedigree data. Heterosis was observed in hybrids for most of the traits, and yield exhibited the highest heterosis among the eight traits examined. The correlation values of GDs with F1 performance were mostly nonsignificant, except for yield, culm length and spikelets per panicle. The correlations of GDs with midparent and better‐parent heterosis were not significant enough to be of predictive value. These results indicate that GDs based on the microsatellite and random amplified polymorphic DNA (RAPD) markers may not be useful for predicting heterotic combinations in ‘Tongil’‐type rice and support the idea that the level of correlation between hybrid performance and genetic divergence is dependent on the germplasm used. 相似文献
14.
Relationship between heterosis and genetic distance based on morphological traits and AFLP markers in pepper 总被引：2，自引：0，他引：2
Genetic diversity is considered as one of the criteria for the selection of parents for hybrid breeding. The present study was undertaken to evaluate genetic divergence among seven pepper cultivars and to assess the relationship between heterosis and parental genetic distance. Twenty‐one F1 hybrids and seven parents were evaluated for 15 morphological characters in a greenhouse and in the field. The parents were examined for DNA polymorphisms using six amplified fragment length polymorphism (AFLP) primer combinations. Cluster analysis using two genetic distance measures grouped the seven parents differently. Mid‐parent and high‐parent heterosis was observed for most characters. Most hybrids outperformed the parental lines for fruit yield, earliness and plant height. Morphological and AFLP‐based distance measurements were efficient enough to allocate pepper genotypes into heterotic groups. The correlations of morphological distances with mid‐parent heterosis were significant for days to flowering and maturity, suggesting earliness can be predicted from morphological distances of parental lines. However, the correlations of AFLP‐measured genetic distances with mid‐ and high‐parent heterosis were non‐significant for all characters, except for fruit diameter, and proved to be of no predictive value. 相似文献
15.
杂交水稻产量及农艺性状杂种优势分析 总被引：1，自引：1，他引：1
为探讨杂种优势与双亲值、双亲一般配合力（GCA）、组合特殊配合力（SCA）、双亲遗传距离的关系,利用10个不育系和10个恢复系,按不完全双列杂交配制100个组合,对杂交水稻产量及农艺性状的杂种优势进行了分析,探索杂种优势的预测方法。结果表明：杂种一代的超亲优势和对照优势主要体现在穗长、每穗总粒数、每穗实粒数几个性状上,其具有正向超亲优势组合的比例分别达到61.0%、66.0%和53.0%,具有正向对照优势的比例分别为62.0%、78.0%和79.0%,结实率性状具有正向对照优势的比例也达到58.0%。杂种优势与父母本值、父母本平均值、高亲值、低亲值及父母本差值都有较为密切的关系,超亲优势与高亲值在8个性状上都极显著相关;对照优势与母本值、父母本平均值、高亲值都呈显著或极显著正相关。杂种优势与SCA和亲本的GCA效应值密切相关,特别是对照优势与SCA和双亲的GCA都呈显著或极显著正相关,同时与父母本的GCA之差和之和都有较大的关系。杂种优势与遗传距离的关系比较复杂,当遗传距离在5~5.5范围内,双亲的距离越远,杂种优势越强。 相似文献
16.
Eight-parental diallel cross and SSR molecular markers were used to determine the combining ability of common wheat lines grown under well-watered (WW) and water-stress (WS) conditions. Analysis of variance of yield indicated highly significant differences among the progenies. General combining ability (GCA) determined most of the differences among the crosses. Specific combing ability (SCA) was also significant but less important. The estimates of GCA effects indicated that one line was the best general combiner for grain yield under drought. Neis genetic distance, measured using SSR markers, differed from 0.20 to 0.48 among the eight genotypes. The correlation of Neis genetic distance with SCA for grain yield and heterosis ranged from 0.4 to 0.5. These results indicate that the level of SCA and heterosis depends on the level of genetic diversity between the wheat genotypes examined. Microsatellite markers were effective in predicting the mean and the variance of SCA in various cultivars combinations. However, selection of crosses solely on microsatellite data would miss superior combinations. 相似文献
17.
Summary The objectives of this research were to evaluate the response to day length and the yield stability of environments of 4x families from 4x×2x crosses in potato. Twenty families from crosses between 4x female parents with different genetic backgrounds and 2x parents, which formed 2n pollen by first division restitution and were selected under short days, were evaluated in four locations in Peru (short days) and during two years at Rhinelander, USA (long days). Results from the USA indicate that the 4x progeny from 4x×2x crosses were very late maturing and poor yielding.Further, vine maturity, tuber size and tuber number are highly correlated with the percentage of Tuberosum germplasm in the parentage. Results from Peru indicate that most 4x×2x families had high tuber yield, stability for yield and high dry matter content. The lack of correlation between rank order of the parental value, based on progeny testing, of the male and female parents among short day locations and between short and long day environments indicates that selection of parents must be done in each location in which the final product, either a family or a clone, will be used.International Potato Center (CIP) 相似文献
18.
The present study aimed to assess the effect of contrasting levels of molecular and phenotypic diversity among polycross parents of orchardgrass on the performance of synthetic progeny with respect to physiological responses and drought tolerance. Four polycross groups each composed of six parental plants were evaluated under normal irrigation and drought stress conditions. A number of 923 inter simple sequence repeats and sequence related amplified polymorphism markers and several phenotypic traits were used to select contrasting levels of diversity (high and low) in parental genotypes. Highly significant correlation was observed between molecular distance and progeny performances at both normal irrigation and drought stress conditions. High molecular diversity among polycross parents led to a significant yield advantage of first generation progeny with averages of 34.40% for normal irrigation and 48.10% for drought stress conditions. Also crosses between genetically distant parents produced progeny with considerable drought tolerance and yield stability. Positive associations between phenotypic distance of parents and progeny performance were found for most physiological traits at both moisture regimes but phenotypic distances had weak association with forage yield, stress tolerance index and yield stability of progeny. Significant associations between drought tolerance index and some physiological traits confirmed the importance of these traits in conferring drought tolerance of orchardgrass. Our results underscore the effectiveness of marker‐assisted polycross breeding to improve drought tolerance and yield stability through physiological traits in orchardgrass. 相似文献
19.
Summary The relationship between the genetic distance of parents and both the heterosis of F1 hybrids and the variance of F5 lines was investigated in 72 crosses of pea (Pisum sativum L.). The genetic distance between each pair of parents was estimated, using isozyme (GDi), morphological (GDm) or quantitative (GDq) markers and finally a combination of isozyme and morphological markers (GDi+m). GDm was poorly correlated with the other measures of genetic distance, which in turn were strongly correlated with each other. Genetic distance was moderately correlated with the level of heterosis for yield over midparent in the F1 generation, with the highest correlation obtained from GDi+m. GD was not significantly correlated with heterosis for yield over the better or best parent but it was significantly correlated with all three measures of heterosis for pods per plant and hundred seed weight. There was no correlation between genetic distance and the level of heterosis for yield and total dry matter in the F2 generation, but GDi, GDi+m and GDq were predictive for the level of inbreeding depression in grain yield and total dry matter. When parents were high in genetic distance, crosses produced highly transgressive segregants for basal branches per plant, hundred seed weight, harvest index and onset of flowering. Genetic distance between parents was thus a useful measure for predicting a portion of hybrid performance and also of the variance of derived inbred lines. It was concluded that when choosing parents for a cross, consideration should be given to their genetic distance as well as their overall adaptation and their yield. There is considerable potential for optimising choice of parental combinations in the development of improved pea cultivars. 相似文献
20.
Toby A. Joyce Michael T. Abberton T.P.T. Michaelson-Yeates John W. Forster 《Euphytica》1999,107(3):159-165
The RAPD-PCR technique has been used to generate DNA amplification profiles from a set of advanced generation inbred lines
of white clover ( Trifolium repens L.). The genetic distances between lines have been estimated and have been compared with
the extent of positive heterosis for dry matter yield in hybrid crosses. The analysis clearly separated the four major groups
(H, J, R and S), with little within group variation. Heterosis, previously shown to be positively correlated with the extent
of phenotypic variation between parental lines, was greatest between lines from groups showing the least genetic distance.
The lack of correlation between heterosis and genetic divergence is discussed in the context of results from other systems.
Additionally, the data allow a comparison of the extent of phenotypic variation for a trait under selective pressure with
the degree of variation at the DNA level detected with the RAPD technique.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献