Analysis of Diallel Table for Experiments in Block Designs

In this paper the analysis of genotypes obtained in diallel crossing system, including parents, one set of F₁s and reciprocal F₁'s, is given. This analysis is presented for data obtained from the experiments laid out in block designs. The analysis of variance, estimator of reciprocal effects, estimators of general and specific combining abilities as well as statistics for testing of hypotheses concerning those parameters are given.     

Analysis of Diallel Table for Experiments Carried Out in BIB Designs-Mixed Model

In this paper the analysis of genotypes obtained in a diallel crossing system, including parents, one set of F₁′s and reciprocal F₁′s, is given. This analysis is presented for data obtained from the experiments carried out in a block design in which block effects are random. The analysis of variance, estimators of reciprocal effects, estimators of general and specific combining abilities are considered. Also statistics for testing hypotheses concerning some genetical parameters are given.     

The Analysis of Partial Diallel Crosses

The analysis of offsprings from the partial diallel crosses is presented. In considered type of crossing, p parental forms into H separate groups are devided. Single crosses among parental forms, from separate groups only, are performed. The analysis for experiments laid out in efficiency balanced block designs is given.     

RFLP markers and predicted testcross performance of maize sister inbreds

 Inbreds selfed from the same F₂ or backcross population are referred to as sister inbreds. In some situations, maize (Zea mays L.) sister inbreds may not have testcross data available for best linear unbiased prediction (BLUP) of single-cross performance. This study evaluated the usefulness of BLUP and restriction fragment length polymorphism (RFLP)-based coefficients of coancestry ( f ) in predicting the testcross performance of sister inbreds. Parental contributions (p) were estimated from 70 RFLP loci for 15 inbreds that comprised three sister inbreds selfed from each of five F₂ populations. Estimates of p were subsequently used to calculate RFLP-based f. Grain yield, moisture, and stalk lodging data were obtained for 2265 single crosses tested by Limagrain Genetics in multilocation trials from 1990 to 1995. Performance of the sister inbreds when crossed to several inbred testers was predicted from the performance of the tested single crosses and RFLP-based f. Correlations between predicted and observed performance, obtained with a delete-one cross-validation procedure, were erratic and mostly low for all three traits. Correspondence was poor between ranks for predicted and observed general combining ability of the sister inbreds. The results suggested that the proportion of the genome derived by a sister inbred from a given parental inbred does not solely determine its testcross performance. The failure of BLUP and RFLP-based f to consistently predict testcross performance indicated that actual field testing will continue to be necessary for preliminary evaluation of sister inbreds. Received : 17 March 1997 / Accepted : 18 April 1997     

Selection for increased nodule number in common bean (Phaseolus vulgaris L.)

Common bean (Phaseolus vulgaris L.) plants were grown for 21–28 days in plastic container-modified Leonard jar assemblies and placed in a controlled-environment room. The nodules on each plant were removed, counted; selected plants were repotted, grown and intercrossed to produce progenies for the next cycle of recurrent selection. Among the ten parent lines, Puebla 152 and WBR 22–34 produced the most nodules and Rio Tibagi and Negro Argel the fewest, when averaged over five experiments. An analysis of number of nodules on F₁ plants resulting from crosses made in a partial diallel design among the ten parents revealed highly significants variation for general combining ability (GCA) but not for specific combining ability (SCA). After three cycles of recurrent selection for nodule number per plant, the mean nodule number was 211% of the mean for the 10 parents control. Total nodule weight on selected plants also increased, but individual nodule weight decreased. Nineteen C₁ and 18 C₂ lines resulting from the individual plants selected for greater nodule number, along with the ten parents and two non-nodulating soybean lines included as non-fixing check plants were grown in a single experiment in a low-N field. C₂ lines on average accumulated significantly more N per plant than either the parents or C₁ lines, providing evidence for increased N₂ fixation measured by the N difference method. These data show that more nodules, possibly resulting from greater susceptibility to nodulation, are an important, heritable component of symbiosis and that selection for increased nodule number resulted in lines capable of fixing more atmospheric N₂.     

The effect of population structure on the relationship between heterosis and heterozygosity at marker loci

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.     

Combining ability and parental evaluation in five selected clones of sugarcane (Saccharum sp. hybrids)

Summary Five Hawaiian commercial sugarcane (Saccharum sp. hybrids) clones were crossed in a full diallel. Four morphological characters were studied in the progeny: number of millable stalks per plant, stalk diameter, stalk length, and sucrose content. A fifth character, plant volume, was calculated from stalk number, stalk diameter and stalk length. The five selected parental clones were treated as fixed variables in the analysis. General combining ability (gca) was significant for all five characters; specific combining ability (sca) was significant for stalk diameter, stalk length, and plant volume. The variance for gca was large in all progeny populations. However, the variance for sca was large in the progeny of only some clones and/or for some individual characters. Parents were evaluated on the basis of their general combining ability: clone H49-3533 had high gca for sucrose content, while clone H53-5356 had high gca for plant vigor.Published with the approval of the Director as Journal Series Paper No. 455, Experiment Station, Hawaiian Sugar Planters' Association.     

Combining ability for resistance in peanut (Arachis hypogaea) to Peanut bud necrosis tospovirus (PBNV)

The combining abilities of field resistance to peanut bud necrosis disease (PBND) caused by Peanut bud necrosis tospovirus (PBNV) were examined to understand the type of gene action governing resistance to the disease, and to identify peanut lines suitable for use as parents in a PBND‐resistance breeding programme. The Ft and F2 progenies from a six‐parent diallel cross and their parents were evaluated under field conditions. They were assessed for disease incidence at 30, 40, 50 and 60 days after planting (DAP), and reactions of the lines to the disease could be best differentiated at 50 and 60 DAP. Results indicated highly significant general combining ability (GCA) effects for PBND incidence in F₁ and F₂ generations. Specific combining ability (SCA) and reciprocal effects were also found to be significant, but their relative contributions to variation among crosses were much less than those of GCA effects. These results suggested that the type of gene action governing resistance to PBND was mainly additive, and selection for PBND resistance in these populations should be effective. Strong correlation coefficients between parental means and GCA effects for disease incidence were seen in both Ft and F2 generations, suggesting that per se performance of the parental line could be used as a predictor of the capability of the line to transmit its PBND‐resistant attribute to progenies. The reciprocal effects were in favour of using resistant lines as female parents. The peanut lines ICGV 86388, 1C 10 and 1C 34 were found to be suitable for use in a PBND–resistance breeding programme.     

Genetics of transgressive segregation for yield and yield components in wheat

Three crosses of spring wheat (Triticum aestivum L. em Thell) involving six cultivars (WC29, WH291, SGP 14, RAJ. 1972, WH377 and HD 2329) were selected on the basis of combining ability analysis to study genetics of transgressive segregation for tillers/plant, grains/spike, 1000 grain weight and grain yield/plant using various mating designs. Diallel analysis indicated that both additive and non- additive components were significant for all the characters. On the basis of general combining ability and specific combining ability effects, the parents WH 291 and WH 377 were found to be good general combiners for tillers/ plant, 1000 grain weight and grain yield/plant. For grains/spike SGP 14 was found to be a good general combiner. The cross WH 377 × HD 2329 for tillers/plant, SGP 14 × Raj. 1972 for grains/spike and grain yield/plant and WC 29 × WH 291 for 1000 grain weight were found to be good cross combinations. Generation mean analysis indicated that the additive-dominance model was inadequate for all the characters in all the crosses except for 1000 grain weight in WC29 × WH291. Additive component was more pronounced than non-additive components for all the characters in all the crosses except for tillers/ plant in WH 377 × HD 2329. Predictions for transgressive segregants from F₃ was more accurate than that from generation mean analysis. However, prediction from both the sources were equally efficient if additive-dominance model was adequate. In general, observed frequencies of transgressive segregants were more in F₂ and BIPi than F₄ but the majority of them were discarded on progeny testing. Biparental mating had an impact in increasing the frequencies of transgressive segregants for different characters in all the crosses. The crosses, WH 377 × HD 2329 for grain yield/ plant, SGP 14 × Raj. 1972 for tillers/plant and WC 29 × WH 291 for grains/spike and 1000 grain weight were found to be potential crosses for transgressive segregants. A comparison of combining ability of parents and crosses, and observed and predicted frequencies of transgressive segregants indicated that the potential crosses for transgressive segregants were those that had high sea effects and involved high and low general combiners. The crosses involving low general combiners irrespective of their sea effects showed poor performance with respect to transgressive segregation.     

Evaluation of circulant partial diallel crosses in maize

Summary The present study was conducted in maize (Zea mays L.) on crosses among 20 diverse parents. The materials were evaluated in four different environments for eight characters. Combining ability analysis was carried out following diallel and partial diallel crosses. The number of crosses per parent (s) varied from 3 to 19 and the results were studied to identify the critical value of s that would provide an adequate information with minimum resources. The S₅ partial diallel was as good as the S₁₉ for the detection of differences among general combining ability (GCA) effects. Even the S₃ gave adequate information in the case of characters with high heritability. However, partial diallel analysis was less efficient in detecting the differences due to specific combining ability (SCA) effects. These results varied with environments, and characters with low heritability were more prone to misinterpretation. GCA effects showed fluctuations in partial diallel analysis which were more pronounced in S₅ and S₃, particularly for characters with low heritability. The average standard error of difference between GCA effects increased with a decrease in s, with a steep slope for s < 7. The partial diallel analysis was more efficient for the estimation of the variance component of GCA than for SCA, as the estimate of SCA was biased upwards. Estimates of broad sense heritability obtained from the partial diallels agreed with the full diallel analysis better than the narrow sense estimates. Smaller partial diallels gave erratic estimates of heritability, particularly for the characters with low heritability.     

Statistical Analysis of Factorial Diallel Design over Environments

Starting from the experimental situation that in each of a environments all mp combinations between m maternal and p paternal genotypes are raised in b replications (blocks), a linear model is formulated for a quantitative character. On the basis of this model formulae for the analysis of variance are given. The expectations of mean squares as well as the estimations of effects (general and specific combining ability and their interaction terms with environments) and their variances are given for different combinations of fixed and random factors.     

Combining ability analyses of stability parameters and forage yield in smooth bromegrass

Summary Twenty-one progenies of smooth bromegrass (Bromus inermis Leyss.) from a 7 X 7 half diallel cross, with their parents, were evaluated for three years at four locations in Alberta for the genetic variation of stability in expression of their annual yield. The linear response and deviation from linear response for each genotype were the two stability parameters considered, together with mean performance in the evaluation of each genotype. Four high yielding genotypes, namely 12, 13, 16, and 26, had general adaptability, while genotype 23 was especially suited to a poor environment. Combining ability analysis showed that general combining ability (GCA) and specific combining ability (SCA) were both important in the expression of yield. Inheritance of linear regression was controlled predominantly by GCA whereas both GCA and SCA were equally important in the expression of deviation. The presence of a substantial proportion of variability due to the additive genetic component in the linear response suggests that it should be possible to exploit this fraction of variability in developing high yielding stable cultivars.     

Genetic analysis of plant regeneration in rice (Oryza sativa L.)

Summary A diallel study involving reciprocal crosses of four genotypes (IR8, 36, 54, and 64) was carried out to understand the genetic mechanism of plant regeneration from immature embryo-calli in rice. Regeneration frequency (% of calli that produced plants) varied from a high of 86% for IR54 to a low of 0% for IR36, while regenerated plants per embryo numbered from 0 to 7 when these same IR lines and the F₁ hybrids were compared. Combining ability analysis revealed that both nuclear (with both additive and dominant effects) and cytoplasmic genes are important in controlling regeneration in rice. Parental lines and F1 hybrids with high ability to regenerate were identified.     

Differences in crystal properties and ligand affinities of an antifluorescyl fab (4-4-20) in two solvent systems

An antigen-binding fragment (Fab) from a murine monoclonal antibody (4-4-20) with high affinity for fluorescein was cocrystallized with ligand in polyethylene glycol (PEG) and 2-methl-2,4-pentanediol (MPD) in forms suitable for X-ray analyses. In MPD the affinity of the intact antibody for fluorescein was 300 times lower than the value (3.4 × 10¹⁰ M^?1) obtained in aqueous buffers. This decreased affinity was manifested by the partial release of bound fluorescein when MPD was added to solutions of liganded Feb during crystallization trials, In PEG, the ligand remained firmly bound to the protein. The liganded Feb crystallized in the monoclinic space group P2₁ in PEG, with a = 58.6, b = 97.2, c = 44.5 Å and β = 95.2°. In MPD the space group was triclinic P1, with a = 58.3, b = 43.4, c = 42.3 Å, α = 83.9°, β = 87.6°, and γ = 84.5°. X-ray diffraction data were collected for both forms to 2.5-Å resolution. Surprisingly, the triclinic form of the liganed antifluorescyl Feb had the same space group, closely similar cell dimensions, and practically the same orientation in the unit cell as an unliganded Fab (BV04-01) with activity against single-stranded DNA.     

深海热液生物共附生可培养硫氧化细菌的多样性及硫氧化特性

[背景]深海热液环境中存在大量H2S及含硫化合物,许多微生物与大型生物形成了紧密的共生体系,例如硫氧化细菌,它们利用其独特的代谢体系协助宿主更好地适应极端环境,但目前尚未对热液底栖生物共附生的硫氧化细菌进行培养鉴定和功能分析.[目的]了解深海热液生物共附生硫氧化细菌的种群特征和功能特征,筛选出深海热液生物共附生微生物中...     

Genome‐wide association analyses reveal the genetic basis of combining ability in rice

Combining ability is a measure for selecting elite parents and predicting hybrid performance in plant breeding. However, the genetic basis of combining ability remains unclear and a global view of combining ability from diverse mating designs is lacking. We developed a North Carolina II (NCII) population of 96 Oryza sativa and four male sterile lines to identify parents of greatest value for hybrid rice production. Statistical analyses indicated that general combining ability (GCA) and specific combining ability (SCA) contributed variously to different agronomic traits. In a genome‐wide association study (GWAS) of agronomic traits, GCA and SCA, we identified 34 significant associations (P < 2.39 × 10^?7). The superior alleles of GCA loci (Ghd8, GS3 and qSSR4) accumulated in parental lines with high GCA and explained 30.03% of GCA variance in grain yield, indicating that molecular breeding of high GCA parental lines is feasible. The distinct distributions of these QTLs contributed to the differentiation of parental GCA in subpopulations. GWAS of SCA identified 12 more loci that showed dominance on corresponding agronomic traits. We conclude that the accumulation of superior GCA and SCA alleles is an important contributor to heterosis and QTLs that greatly contributed to combining ability in our study would accelerate the identification of elite inbred lines and breeding of super hybrids.     

Estimation,variance and optimal sampling of gene diversity II. Diploid locus

Nei's analysis of diversity at a diploid locus is extended to a population subdivided into a large number of subpopulations. The diversities and the heterozygotes frequency are defined with respect to the total population and unbiasedly estimated in a two-stage random cluster sampling. The fixation indices F _IS, F _IT andF _ST are derived, then inter- and intra-population variances of the estimated parameters are studied. We show that there is a unique sample size per population which yields the best accuracy in estimatingF _ST and F _IS, respectively, at a given locus. These results are illustrated with an analysis of DNA diversity in a forest tree and compared to those obtained under the Hardy-Weinberg assumption.     

Some Theoretical Aspects of Analysis in Half Diallel

The analysis of F₁ and F₂ half diallel has been discussed as compared to full diallel without reciprocal effects given by MATHER and JINKS (1971). In practice, mostly the half diallel (one-way) crosses are prepared and erroreously analysed using the least square estimates of full diallel without reciprocal effects. The H₁ and H₂, however, appeared to be over estimated when full diallel without reciprocal effects estimates were used in place of those of half diallel. Least square estimates were also obtained assuming heterogeneity of error components between parents and F₁/F₂ families.     

Energetics of Saccharomyces cerevisiae CBS 426: Comparison of anaerobic and aerobic glucose limitation

Saccharomyces cerevisiae CBS 426 was grown aerobically and anaerobically in a glucose-limited chemostat. The flows of biomass, glucose, ethanol, carbon dioxide, oxygen, glycerol, and the elemental composition of the biomass were measured. Models for anaerobic and aerobic growth are constructed. Values for Y_ATP and P/O are obtained from continuous culture data for aerobic growth; this Y_ATP value is compared with that obtained from the anaerobic growth results. The ratio between the heat produced and the oxygen consumed increases if more glucose in fermented to ethanol and carbon dioxide. An equation for ?_H/?_O as a function of the respiratory quotient is given.     

Inheritance of partial resistance to bean rust in the common bean (Phaseolus vulgaris L.)

The inheritance of partial resistance within eight bean cultivars to a single-pustule isolate of bean rust was studied by means of a F₁ diallel test. General combining ability (GCA) and specific combining ability (SCA) were very highly significant over two seasons and in interaction with seasons. The partitioning of the sums of squares indicated the greater importance of GCA in the inheritance of the resistance. Reciprocal effects were not significant. The estimates of narrow-sense heritability in the two seasons were 0.899 ± 0.056 and 0.603 ± 0.065.