油用向日葵主要农艺性状的遗传效应及相关性研究

根据加性-显性与环境互作的遗传模型,对6个油用向日葵自交系及其配制的9个杂交组合在2个环境下的7个农艺性状表现进行遗传分析,揭示油用向日葵主要农艺性状遗传性质、规律以及主要农艺性状对含油率的贡献率。结果表明:株高、茎粗、盘径、百粒重、籽仁率和单盘粒重等6个遗传性状主要受加性和显性共同控制,结实率的遗传以加性、显性×环境互作效应为主,籽仁率、单盘粒重以加性、显性、显性×环境互作效应为主;性状间的各项遗传相关性多以加性遗传相关为主。百粒重的净效应对籽实含油率的加性遗传方差贡献率最高,结实率的净效应对籽实含油率的显性遗传方差贡献率最高,单盘粒重对籽实含油率的加性×环境互作遗传方差的贡献率最高。     

Cotton chromosome substitution lines crossed with cultivars: genetic model evaluation and seed trait analyses

Seed from upland cotton, Gossypium hirsutum L., provides a desirable and important nutrition profile. In this study, several seed traits (protein content, oil content, seed hull fiber content, seed index, seed volume, embryo percentage) for F₃ hybrids of 13 cotton chromosome substitution lines crossed with five elite cultivars over four environments were evaluated. Oil and protein were expressed both as percentage of total seed weight and as an index which is the grams of product/100 seeds. An additive and dominance (AD) genetic model with cytoplasmic effects was designed, assessed by simulations, and employed to analyze these seed traits. Simulated results showed that this model was sufficient for analyzing the data structure with F₃ and parents in multiple environments without replications. Significant cytoplasmic effects were detected for seed oil content, oil index, seed index, seed volume, and seed embryo percentage. Additive effects were significant for protein content, fiber content, protein index, oil index, fiber index, seed index, seed volume, and embryo percentage. Dominance effects were significant for oil content, oil index, seed index, and seed volume. Cytoplasmic and additive effects for parents and dominance effects in homozygous and heterozygous forms were predicted. Favorable genetic effects were predicted in this study and the results provided evidence that these seed traits can be genetically improved. In addition, chromosome associations with AD effects were detected and discussed in this study.     

Genetic analysis of agronomic characters in chickpea. II. Estimates of genetic variances from line × tester mating designs

Summary Thirty line x tester experiments involving diverse chickpea (Cicer arietinum L.) germplasm were conducted over 8 years and three locations to determine the nature of the genetic variance for grain yield and related characters, and the effects of generation and environment on these genetic parameters. Days-to-flowering, 100-seed mass, and seeds per pod were predominantly under the control of additive genetic variance, while both additive and non-additive genetic components of variance were important for days-to-maturity, plant height, primary and secondary branches, pods per plant, and seed yield. The F₁ and F₂ generations were found equally useful in estimating the genetic variances for different characters because the generation did not significantly interact with genetic parameters in the majority of cases. Sites or seasons, on the other hand, showed significant interaction with genetic components of variances; additive variance showed a larger interaction with environments than non-additive variance. This indicated the importance of more than one site and/ or season for unbiased estimation of the genetic components of variance. The results were compared with previous findings from diallel analyses.ICRISAT Journal Article No. 1200     

Inheritance of seed protein content and other agronomic characters in long bean (Vigna sesquipedalis Fruw.)

Summary Seven varieties of long bean, which included three local and four exotic, were crossed in a complete diallel. This was an attempt to study the inheritance of crude protein content, protein yield, flowering date, pod yield and yield components.Both additive and non-additive gene effects were responsible for the genetic variation in the diallel population. However, dominance variance was more important than additive variance in crude protein content, number of pods per plant and number of seeds per pod. For seed weight and pod length, additive variance was more important.The crude protein content, protein yield and number of pods per plant appeared to be controlled by overdominance effects. Partial dominance seemed to be the case for flowering date, pod length and seed weight; complete to overdominance for pod yield. High protein appeared to be associated with recessive genes whereas there was a general trend of high yielding parents carrying more dominant genes.     

Quantitative genetics of speciation: additive and non-additive genetic differentiation between <Emphasis Type="Italic">Drosophila madeirensis</Emphasis> and <Emphasis Type="Italic">Drosophila subobscura</Emphasis>

The role of dominance and epistasis in population divergence has been an issue of much debate ever since the neoDarwinian synthesis. One of the best ways to dissect the several genetic components affecting the genetic architecture of populations is line cross analysis. Here we present a study comparing generation means of several life history-traits in two closely related Drosophila species: Drosophila subobscura, D. madeirensis as well as their F ₁ and F ₂ hybrids. This study aims to determine the relative contributions of additive and non-additive genetic parameters to the differentiation of life-history traits between these two species. The results indicate that both negative dominance and epistatic effects are very important in the differentiation of most traits. We end with considerations about the relevance of these findings for the understanding of the role of non-additive effects in speciation.     

Inheritance of seed yield and quality traits in peas (Pisum sativum L.)

Summary A half diallel analysis involving nine cultivars showed that additive as well as non-additive gene effects were important for the inheritance of seed yield per plant, 100-seed weights, protein content and potassium per cent. For remaining traits non-additive genetic components were important. Overdominance was observed for all traits except for 100-seed weight, which expressed partial dominance. Parents PMR-T10, EC21857, EC109182, T163 and EC109189 were good general combiners for seed yield, seed weight and quality traits. In general there was a good relationship between per se performance and the gca effects of the parents for all traits. Cross combinations such as LMR8 x EC109182,LMR8 x PMR-T10,LMR8 x EC21857,PMRT10 x EC21857 and P23 x EC21857 were found promising. The seed yield was positively correlated with other quality traits. Protein had a positive correlation with methionine and phosphorus. All the values of correlation co-efficients were non-significant except for yield with potassium, 100-seed weight and protein with methionine, indicating that yield and quality attributes can be improved simultaneously by simple selection procedures.     

Genetic Analysis for F1 Yield Traits with Conditional Approach in Island Cotton (Gossypium barbadense L.)

A genetic model with additive, dominance and genotype × environment interaction effect was employed to analyze the 3-year data of F₁ hybrids from 5 × 4 diallel cross, whose parents were Island cotton and had different fruit branch types. Unconditional and conditional genetic variances were conducted for analyze genetic impacts of yield components on yield. Results of unconditional genetic variances showed that there were no additive variance of total lint yield. But conditional additive effects of total lint yield, when excluding the phenotype of boll weight, boll number at prefrost, boll number at postfrost, and lint yield at prefrost, indicated that improving the additive effects of the total lint yield was still possible. Crossing and selecting component traits with high contributive additive effects could obtain good offsprings. Yield components contributed large dominance effects to the heterosis of lint yield at prefrost and total lint yield in crosses. Yield component traits were controlled with each other. The traits having positive contributive effects could be applied to further improve target traits.     

Genetic analysis of agronomic characters in chickpea

Summary Twenty-eight diallel trials over 8 years and two locations were analysed to estimate genetic variances for agronomic characters of chickpea (Cicer arietinum L.). The data were analysed according to Method 4 and Model I of Griffing (1956). Days to flowering, plant height, and seed size were found to be predominantly under additive inheritance and were highly predictable. Both additive and non-additive genetic components were important for seed yield, number of branches, pods per plant, and seeds per pod. Although both general combining ability (gca) and specific combining ability (sca) varied significantly with generation, components of gca mean squares were invariably much larger than gca x generation interaction components, indicating that either the F₁ or the F₂ generation can be used to estimate the gca components effectively. Combined diallel analysis of F₂s over locations revealed the importance of combining ability x location interactions and emphasized the need for testing over more than one location for the precise estimation of combining ability. The implications of these findings and those reported earlier in the literature on the breeding strategies/methods for the genetic improvement of agronomic characters in chickpea are discussed.ICRISAT journal article no. 1199     

Germination of Talinum triangulare L. Seeds as Affected by Various Chemical and Physical Treatments

Three-month ‘old’ and ‘fresh’ seedsof Talinum triangulare were subjected to various treatmentsto induce early and rapid germination. Scarification and activated carbon were the most effective treatmentsin improving total germination in fresh seeds, while the 3 and5 per cent thiourea treatments were most effective in improvingtotal germination in old seeds. Activated carbon, scarificationand 5 per cent thiourea treatments enhanced early germinationin both old and fresh seeds. Cumulative percentage germinationwas very high in fresh seeds after scarification or after treatmentwith activated carbon and 5 per cent thiourea, and lowest inseeds treated with 3 per cent thiourea and hot water. In oldseeds, highest cumulative percentage germination was obtainedwith 3 and 5 per cent thiourea treatments and scarification.Generally, higher germination was obtained with fresh seedsthan with old seeds. Partial seed-coat removal and treatment with 5 per cent thiouriaresulted in a higher rate of and cumulative percentage germinationcompared with seeds with the coat partially removed but nottreated with thiourea. Constantly high temperature (34 °C) increased both rateand total germination compared with seeds planted at room temperature(20–23 °C). Treatments that did not induce germinationwere 1 per cent thiourea, H₂SO₄, cold water soaking at roomtemperature, 6 per cent hydrogen peroxide and soil planting.These treatments effected less than 3 per cent germination. Talinum triangulare L, seed scarification, activated charcoal, thiourea, germination     

Line x tester analysis for fixed effect model in cotton (Gossypium hirsutum L.)

Summary The data from an experiment in cotton consisting of three testers and 12 lines selected deliberately have been analysed. The investigation showed higher specific combining ability variance for yield of seed cotton and number of bolls, indicating the predominance of non-additive gene action. Of parental lines, H777 was found to possess high g.c.a. effects for seed cotton yield, number of bolls and number of sympodes. Parent H842 contributed only for boll weight, whereas H655 was good general combiner for number of monopodes. There appeared to be better chances for increasing the yield by exploiting hybrid vigour for the number of bolls and boll weight. The presence of marked non-additive gene effects, in addition to additive gene effects, indicated the need for exploiting both the fixable and non-fixable components of genetic variance for increasing productivity in cotton.     

Interspecific chromosomal effects on agronomic traits in Gossypium hirsutum by AD analysis using intermated G. barbadense chromosome substitution lines

The untapped potential of the beneficial alleles from Gossypium barbadense L. has not been well utilized in G. hirsutum L. (often referred to as Upland cotton) breeding programs. This is primarily due to genomic incompatibility and technical challenges associated with conventional methods of interspecific introgression. In this study, we used a hypoaneuploid-based chromosome substitution line as a means for systematically introgressing G. barbadense doubled-haploid line ‘3-79’ germplasm into a common Upland genetic background, inbred ‘Texas marker-1’ (‘TM-1’). We reported on the chromosomal effects, lint percentage, boll weight, seedcotton yield and lint yield in chromosome substitution CS-B (G. barbadense L.) lines. Using an additive-dominance genetic model, we studied the interaction of alleles located on two alien substituted chromosomes versus one alien substituted chromosome using a partial diallel mating design of selected CS-B lines (CS-B05sh, CS-B06, CS-B09, CS-B10, CS-B12, CS-B17 and CS-B18). Among these parents, CS-B09 and CS-B10 were reported for the first time. The donor parent 3-79, had the lowest additive effect for all of the agronomic traits. All of the CS-B lines had significant additive effects with boll weight and lint percentage. CS-B10 had the highest additive effects for lint percentage, and seedcotton and lint yield among all of the lines showing a transgressive genetic mode of inheritance for these traits. CS-B09 had greater additive genetic effects on lint yield, while CS-B06, CS-B10 and CS-B17 had superior additive genetic effects on both lint and seedcotton yield compared to TM-1 parent. The 3-79 line had the highest dominance effects for boll weight (0.513 g) and CS-B10 had the lowest dominance effect for boll weight (?0.702). Some major antagonistic genetic effects for the agronomic traits were present with most of the substituted chromosomes and chromosome arms, a finding suggested their recalcitrance to conventional breeding efforts. The results revealed that the substituted chromosomes and arms of 3-79 carried some cryptic beneficial alleles with potential to improve agronomic traits including yield, whose effects were masked at the whole genome level in 3-79.     

The consequences of including non-additive effects on the genetic evaluation of harvest body weight in Coho salmon (Oncorhynchus kisutch)

Background

In this study, we used different animal models to estimate genetic and environmental variance components on harvest weight in two populations of Oncorhynchus kisutch, forming two classes i.e. odd- and even-year spawners.

Methods

The models used were: additive, with and without inbreeding as a covariable (A + F and A respectively); additive plus common environmental due to full-sib families and inbreeding (A + C + F); additive plus parental dominance and inbreeding (A + D + F); and a full model (A + C + D + F). Genetic parameters and breeding values obtained by different models were compared to evaluate the consequences of including non-additive effects on genetic evaluation.

Results

Including inbreeding as a covariable did not affect the estimation of genetic parameters, but heritability was reduced when dominance or common environmental effects were included. A high heritability for harvest weight was estimated in both populations (even = 0.46 and odd = 0.50) when simple additive models (A + F and A) were used. Heritabilities decreased to 0.21 (even) and 0.37 (odd) when the full model was used (A + C + D + F). In this full model, the magnitude of the dominance variance was 0.19 (even) and 0.06 (odd), while the magnitude of the common environmental effect was lower than 0.01 in both populations. The correlation between breeding values estimated with different models was very high in all cases (i.e. higher than 0.98). However, ranking of the 30 best males and the 100 best females per generation changed when a high dominance variance was estimated, as was the case in one of the two populations (even).

Conclusions

Dominance and common environmental variance may be important components of variance in harvest weight in O. kisutch, thus not including them may produce an overestimation of the predicted response; furthermore, genetic evaluation was seen to be partially affected, since the ranking of selected animals changed with the inclusion of non-additive effects in the animal model.     

Conditional QTL mapping of oil content in rapeseed with respect to protein content and traits related to plant development and grain yield

Oil content in rapeseed (Brassica napus L.) is generally regarded as a character with high heritability that is negatively correlated with protein content and influenced by plant developmental and yield related traits. To evaluate possible genetic interrelationships between these traits and oil content, QTL for oil content were mapped using data on oil content and on oil content conditioned on the putatively interrelated traits. Phenotypic data were evaluated in a segregating doubled haploid population of 282 lines derived from the F₁ of a cross between the old German cultivar Sollux and the Chinese cultivar Gaoyou. The material was tested at four locations, two each in Germany and in China. QTLMapper version 1.0 was used for mapping unconditional and conditional QTL with additive (a) and locus pairs with additive × additive epistatic (aa) effects. Clear evidence was found for a strong genetic relationship between oil and protein content. Six QTL and nine epistatic locus pairs were found, which had pleiotropic effects on both traits. Nevertheless, two QTL were also identified, which control oil content independent from protein content and which could be used in practical breeding programs to increase oil content without affecting seed protein content. In addition, six additional QTL with small effects were only identified in the conditional mapping. Some evidence was apparent for a genetic interrelationship between oil content and the number of seeds per silique but no evidence was found for a genetic relationship between oil content and flowering time, grain filling period or single seed weight. The results indicate that for closely correlated traits conditional QTL mapping can be used to dissect the genetic interrelationship between two traits at the level of individual QTL. Furthermore, conditional QTL mapping can reveal additional QTL with small effects that are undetectable in unconditional mapping.     

Genetic studies of yield contributing traits in Amaranthus

Summary Genetical studies on grain yield and its contributing traits were made in a six parent complete diallel in the F₁ and F₂ generations of one of the most widely grown grain species of grain amaranths (Amaranthus hypochondriacus L.). Graphical analysis indicated that epistasis exists for 1,000-grain weight in the F₁. Grain weight/panicle, yield/plant and harvest index indicated absence of non-allelic gene interaction. The harvest index in the F₁ and F₂ and grain weight/ panicle, 1,000-grain weight, yield/plant in the F₂ appeared to be controlled by overdominance effects. Higher grain yield appeared to be associated with dominant genes. Both additive and non-additive gene effects were responsible for the genetic variation in the diallel population. However, dominance variance was more important than additive variance in grain yield/ plant and harvest index in the F₁ and F₂. For 1,000-grain weight additive genetic variance was more important in the F₁ and non-additive in F₂. There was overdominance of a consistent nature in the two analyses for harvest index in the F₁ and F₂, grain weight/ panicle, 1,000-grain weight and yield/plant in the F₂ and partial dominance for 1,000-grain weight in the F₁.     

Comparative effects of gibberellins and an N-substituted phthalimide on seed germination and extension growth of celery (Apium graveolens L.)

The N-substituted phthalimide AC 94377 (1-(3-chlorophthalimido)-cyclohexanecarboxamide) was equally effective as a mixture of the gibberellins A₄ and A₇ (GA_4/7) in breaking dormancy and stimulating germination of celery seeds when either was used in combination with ethephon or daminozide as a seed soak. Whereas seedlings emerging from GA_4/7-treated seeds became etiolated in comparison with those from untreated seeds, those from AC 94377-treated seeds showed normal development. Preharvest sprays of gibberellic acid (GA₃) increased the height of mature plants in comparison with untreated controls by about 16 per cent whereas AC 94377 was ineffective. The yield from GA₃-treated plots was about 10 per cent greater than that from AC 94377-treated plots.     

PARENTAL EFFECTS ON SEED DEVELOPMENT AND SEED YIELD IN RAPHANUS RAPHANISTRUM: IMPLICATIONS FOR NATURAL AND SEXUAL SELECTION

The possibility that sexual selection operates in angiosperms to effect evolutionary change in polygenic traits affecting male reproductive success requires that there is additive genetic variance for these traits. I applied a half-sib breeding design to individuals of the annual, hermaphroditic angiosperm, wild radish (Raphanus raphanistrum: Brassicaceae), to estimate paternal genetic effects on, or, when possible, the narrow-sense heritability of several quantitative traits influencing male reproductive success. In spite of significant differences among pollen donors with respect to in vitro pollen tube growth rates, I detected no significant additive genetic variance in male performance with respect to the proportion of ovules fertilized, early ovule growth, the number of seeds per fruit, or mean individual seed weight per fruit. In all cases, differences among maternal plants in these traits far exceeded differences among pollen donors. Abortion rates of pollinated flowers and fertilized ovules also differed more among individuals as maternal plants than as pollen donors, suggesting strong maternal control over these processes. Significant maternal phenotypic effects in the absence of paternal genetic or phenotypic effects on reproductive traits may be due to maternal environmental effects, to non-nuclear or non-additive maternal genetic effects, or to additive genetic variance in maternal control over offspring development, independent of offspring genotype. While I could not distinguish among these alternatives, it is clear that, in wild radish, the opportunity for natural or sexual selection to effect change in seed weight or seed number per fruit appears to be greater through differences in female performance than through differences in male performance.     

Genetic basis of variation of yield, and yield components in mungbean (Vigna radiata (L.) Wilczek)

Additive, dominance, and epistasis genetic basis of seed yield per plant, number of pods per plant, number of seeds per pod, and 1000 seed weight in mungbean (Vigna radiata (L.) Wilczek) have been examined, using Triple Test Cross (TTC) analysis. The material for TTC test was evaluated in two seasons i.e., kharif (July-October) and spring/summer (March-June), at the research station of the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan. Epistasis was present significantly for number of pods per plant and number of seeds per pod when grown in the spring/summer season (March to June). Partition of epistasis showed that additive x additive ('i' type) interaction was an important component of number of pods per plant, and number of seeds per pod was found to be of both types 'i' type, and additive x dominance, and dominance x dominance ('j' and 'l' type) interactions. This indicated that epistasis might be a non-trivial factor in the inheritance of pods per plant, and seeds per pod in mungbean. The expression of epistasis was influenced differentially by particular genotypes, indicating that a limited number of genotypes may not be sufficient to detect non-allelic interactions for a trait in mungbean. Additive and dominance genetic components were significant for all four traits in kharif season (July to October) but only for seed yield and 1000 seed weight in spring/summer season. This suggests that the genes controlling seed yield per plant, and 1000 seed weight are equally sensitive to the environment. The predominance additive gene action in those traits is not significantly influenced by epistasis, suggesting that improvement of the traits can be achieved through standard selection procedures.     

Non-additive genetic effects for fertility traits in Canadian Holstein cattle (Open Access publication )

The effects of additive, dominance, additive by dominance, additive by additive and dominance by dominance genetic effects on age at first service, non-return rates and interval from calving to first service were estimated. Practical considerations of computing additive and dominance relationships using the genomic relationship matrix are discussed. The final strategy utilized several groups of 1000 animals (heifers or cows) in which all animals had a non-zero dominance relationship with at least one other animal in the group. Direct inversion of relationship matrices was possible within the 1000 animal subsets. Estimates of variances were obtained using Bayesian methodology via Gibbs sampling. Estimated non-additive genetic variances were generally as large as or larger than the additive genetic variance in most cases, except for non-return rates and interval from calving to first service for cows. Non-additive genetic effects appear to be of sizeable magnitude for fertility traits and should be included in models intended for estimating additive genetic merit. However, computing additive and dominance relationships for all possible pairs of individuals is very time consuming in populations of more than 200 000 animals.     

The Genetic Architecture of Quantitative Traits Cannot Be Inferred from Variance Component Analysis

Classical quantitative genetic analyses estimate additive and non-additive genetic and environmental components of variance from phenotypes of related individuals without knowing the identities of quantitative trait loci (QTLs). Many studies have found a large proportion of quantitative trait variation can be attributed to the additive genetic variance (V_A), providing the basis for claims that non-additive gene actions are unimportant. In this study, we show that arbitrarily defined parameterizations of genetic effects seemingly consistent with non-additive gene actions can also capture the majority of genetic variation. This reveals a logical flaw in using the relative magnitudes of variance components to indicate the relative importance of additive and non-additive gene actions. We discuss the implications and propose that variance component analyses should not be used to infer the genetic architecture of quantitative traits.     

Characterisation of Soybean and Wheat Seeds by Nuclear Magnetic Resonance Spectroscopy

The effects of equilibration under different air relative humidities (RH, 1 – 90 %) and temperatures (35 and 45 °C) on soybean (Glycine max) and wheat (Triticum aestivum) seeds were studied using different techniques. Seed moisture content, electrical conductivity (EC) of seed leachate and per cent seed germination were measured following standard procedures, and compared with nuclear magnetic resonance spin-spin relaxation time (T₂) measurements. Moisture contents of soybean and wheat seeds, following the reverse sigmoidal trend, were greater at 35 than at 45 °C at any particular RH. Changes in T₂ were related to the changes in germination percentage and leachate EC of both soybean and wheat seeds. Equilibrating soybean seeds at RH 11 % decreased germination percentage with corresponding decrease in T₂. On the contrary, EC of seed leachate increased. In wheat seeds equilibrated at 45 °C, T² was maximal at RH 5.5 %. T₂ declined in seeds equilibrated at high RH (> 80 %) together with low germination percentage.