Diallel analysis for some quantitative characters in Petunia hybrida Hort

Summary Flowering time, plant height and flower size in Petunia hybrida Hort. (multiflora type) have been genetically analysed by means of a 5 × 5 diallel cross. The results indicated that: (1) the three characters are controlled by additive-dominance polygenic systems. The contribution of the additive gene actions to the genetic variance of flowering time was relatively higher than that of dominance. The reverse situation was found for plant height and flower size. (2) Dominance is ambi-directional for the three characters. Ratios of average dominance were in the range of partial for flowering-time, complete for plant height and overdominance for flower size. (3) Number of genes (or gene groups) controlling the characters are about 3, 3 and 5 for flowering time, plant height and flower size: respectively, (4) Heritability estimates are 0.84, 0.88 and 0.89 in the broad-sense and 0.40, 0.49 and 0.37 in the narrow-sense, for flowering time, plant height and flower size; respectively. (5) Heterosis as percent increase of the mean F₁-hybrid above the higher parent, or decrease below the lower parent, was observed for flowering time (+ 9.7% to +13.3%), for plant height (–13.6% to –20.3%) and for flower size (+2.5% to +16.0%).     

Association analysis of some drought related characters in hexaploid spring wheat (Triticum aestivum L.).

The association among yield components and their direct and indirect influence on the grain yield of wheat were investigated. 24 breeding lines were tested in a randomized complete block experiment design with three replications. According to the results the phenotypic correlation among the traits and their path coefficient were estimated. Positive significant correlation coefficients were obtained for association between survival rate treatment I, III, leaf venation, stomatal frequency, osmotic pressure, flag leaf area and number of tillers per plant with grain yield per plant at both phenotypic and genotypic levels. Negatively significant correlation between hygrophilic colloids and epidermal cell size with grain yield per plant was obtained at phenotypic and genotypic levels. Path coefficient was also computed to estimate the contribution of character to the yield. Path coefficient analysis revealed that flag leaf area, root/shoot ratio and survival rate II had the highest positive direct effects on grain yield, while hygrophilic colloids and osmotic pressure had negative direct effect on grain yield. These results thus obtained suggested that flag leaf area is an important component of yield and hence needs special attention in selection strategies.     

Inheritance of internode and culm length in hexaploid Triticale

Summary A diallel cross of twelve cultivars of hexaploid Triticale was made in order to study genie action types for total culm length and for the length of its different segments. Culm length, and four partial lengths of the culm were studied in the F₁ and F₂ generations. The analysis was made according to the Griffing, Hayman and Jinks models. Heterosis in culm length is mainly due to its upper half. Spanish cultivars have, in general, positive GCA and transmit greater height in crosses, whereas the Mexican ones show a negative GCA effect and have a tendency to decrease in height when crossed. Additivity greatly influences the inheritance of culm length, this influence being lower at the first plant internodes. The environmental component has also a large influence in the phenotypic expression of Triticale height. Dominance is only partial for the five traits studied. The predominant kind of interaction seems to be of the duplicate type. All correlations between culm length and its components are high and positive, especially the genetic ones.     

基于SSR标记的六倍体小黑麦遗传多样性分析

采用已筛选出的多态性较好的分布于六倍体小黑麦21对染色体上的100对SSR引物对从国际玉米小麦改良中心(CIMMYT)引进的339份六倍体小黑麦进行了遗传多样性分析。结果显示,100对引物共检测出323个等位变异,变幅是1~6个,平均等位变异丰富度为3.23;多态信息含量(PIC)的变幅为0~0.748,平均多态信息含量为0.465;平均遗传多样性指数(H')为0.1439,说明供试的339份六倍体小黑麦品种的SSR遗传多样性较为丰富。同时基于Nei's遗传距离对339份材料进行聚类分析,可以将供试材料分为6个类群。其中,第Ⅵ类群与其他类群的遗传距离较大、遗传差异较明显。研究结果为将六倍体小黑麦的优良基因应用于普通小麦的遗传改良提供了理论依据。     

Molecular cytogenetic analyses of hexaploid lines spontaneously appearing in octoploid Triticale

Genome characterization of 14 hexaploid lines that spontaneously appeared in octoploid Triticales was carried out by sequential genomic in situ hybridization and fluorescence in situ hybridization, high molecular weight glutenin subunits and SSR marker analyses. All of the lines showed a chromosome constitution of complete A and B genomes, and a composite genome consisting of the chromosomes of D and R genomes. The composite genome of the 11 lines consisted of chromosomes 1R, 2D, 3R, 4R, 5R, 6R and 7R, that of the two lines were 1D, 2D, 3R, 4R, 5R, 6R and 7R, and that of one line was 1R, 2D, 3R, 4R, 5R, 6D and 7R. The incompatibility of the D and R genomes in common wheat genetic background, preferential retention of chromosome 2D and importance of these lines for the development of hexaploid Triticale are discussed in this report.     

Diallel analysis of androgenetic plant production in hexaploid Triticale (X. triticosecale,Wittmack)

Summary Studies were made on the genetic determination of androgenetic plant yield and its two components: embryo production and green plant regeneration. This involved the analysis of a complete 7×7 diallel cross of 4 androgenetic lines and 3 lines obtained by pedigree selection, one of them having the Triticum timopheevi cytoplasm. The three traits analysed are both heritable and environmentally influenced (by season and culture medium composition). The analysis of embryo production shows a mainly nuclear inheritance, with predominantly additive gene action, but also a favourable effect of Triticum timopheevi cytoplasm. Green plant regeneration has a more complex genetic determination, with additive as well as non-additive gene action and cytoplasmic influences. Hybrids appear superior to inbred lines for embryogenesis and green plant yield, but not for green plant regeneration. Androgenetic lines used as parents did not show superiority over other parents either in their own value or in the transmission of androgenetic abilities. Genetic improvement seems to be possible by recombination in progenies of hybrids between lines having complementary abilities.     

Mapping of quantitative trait loci determining agronomic important characters in hexaploid wheat ( Triticum aestivum L.)

A set of 114 recombinant inbred lines of the 'International Triticeae Mapping Initiative' mapping population was grown during the seasons 1997, 1998, 1999 and 2000 under several environments. Twenty morphological (glume colour, awn colour, waxiness, leaf erectness, peduncle length), agronomical (ear emergence time, flowering time, grain filling time, ear length, plant height, lodging, grain number, thousand-grain-weight, grain weight per ear, grain protein content, winter hardiness) and disease resistance (powdery mildew, yellow rust, leaf rust, fusarium) traits were studied. Not all traits were scored in each experiment. In total 210 QTLs with a LOD threshold of >2.0 (minor QTLs) were detected of which 64 reached a LOD score of >3.0 (major QTLs). Often QTLs were detected in comparable positions in different experiments. Homologous and homoeologous relationships of the detected QTLs, and already described major genes or QTLs determining the same traits in wheat or other Triticeae members, are discussed.     

Induced quantitative variation in hexaploid triticale

This is a study of variation induced in a few triticale types through the use of mutagens. The quantitative variation generated in the M₂ generation was analysed statistically. Considerable genetic variation was induced by the mutagens. NMU was a better mutagen than EMS. The induced variation was in both directions, although it extended more in the negative direction. The study indicates the potential usefulness of more extensive mutation breeding experiments aimed at the improvement of triticales for commercial use.     

Diallelic analysis of quantitative traits in hexaploid wheat (Triticum aestivum L.)

Abstract

A complete diallel study of crosses between eight wheat varieties was carried out to determine the relative magnitude of components of genetic variation and heritability for important grain yield, quality and drought‐related traits. The data appeared adequate for the additive‐dominance model. The additive effects predominated for most traits, and consequently the narrow‐sense heritability was high to moderately high for flag leaf area, weight and venation, stomatal frequency and size, epidermal cell size, biomass, protein content, number of tillers, spike length, spike density, 1000‐grain weight and grain yield. These results appear promising for selecting better plants in the segregating populations with some degree of improvement for yield, quality and physiological efficiency.     

Combining ability and heterosis for earliness characters in line x tester population of Gossypium hirsutum L

The objective of this study was to estimate the general combining ability of the parents and specific combining ability of hybrids for earliness traits for line selection. Inheritance and interrelationships of earliness characters were evaluated in a line x tester design. Three intermediate-early-maturing female (lines) which are grown regionally and four early-maturing males (testers) cotton varieties were crossed in 2003. The twelve F(1) and seven parents were planted randomized block design with three replications in 2004. For each earliness trait, general combining ability (GCA) and specific combining ability and gene effects were estimated using the line x tester method of analysis and also were determined heterosis and narrow sense heritability. Parents and their hybrids (except the monopodial branch) were significant for all the earliness traits studied. Estimates of variance due to GCA and SCA and their ratio revealed predominantly non-additive gene effects for date of first square, date of first flowers and harvested rate of first picking. Among the lines, Ersan 92 and Maras 92 and among the testers Acala Royal was found to be the best general combiners for most of the earliness characters. Four out of twelve crosses namely Ersan 92 x Chirpan 603, Ersan 92 x Acala Maxa, Maras 92 x Acala Royal and Nazilli 87 x Acala Royal were found to be the best crosses for investigated earliness characters.     

小麦籽粒品质性状的杂种优势和相关分析

以6个小麦品种（系）组配的6个杂交组合F1为供试材料,对其籽粒品质性状进行了杂种优化、性状相关和亲子相关分析。结果表明：（1）粉质参数中的形成时间和稳定时间杂种优势最强,分别为56.49％和32.23％;籽粒蛋白质含量和硬度的优势最弱,分别为-2.73％和-0.9046％;沉淀值和湿面筋含量的优势居中,分别为6.88％和5.88％。（2）粉质参数中的吸水率、稳定时间同其它几个指标之间呈显著或极显著相关;沉淀值与籽粒蛋白质含量呈正相关,但不显著,与湿面筋含量呈显著负相关;湿面筋含量与籽粒蛋白质含量呈显著负相关。（3）杂种F1的籽粒Zeleny沉淀值与高亲值,低亲值和中亲值呈显著和极显著正相关;籽粒蛋白质含量和湿面筋含量与高亲值,低亲值和中亲值呈负相关或不相关。     

Evolution of sexual preferences in quantitative characters

An analysis of equilibria and dynamics of the means, variances, and covariances of female mating preference for a quantitative male secondary sexual character following a Gaussian model is presented. For many combinations of viability and sexual selection parameters the evolving Gaussian distribution of phenotypes can diverge. The results on the cases of convergence and their limiting forms suggest some reinterpretations of Fisher's "runaway" process of sexual selection. One possibility is to interpret Fisher's postulated "initial advantage not due to female preference" as a shift in viability selection where runaway evolution occurs if the mean preferred trait evolves beyond its new viability optimum (due to sexual selection). This definition is contrasted with situations in which the new viability optimum is undershot. The quantitative and qualitative conclusions differ from models that approximate genetic covariance evolution involving a constant covariance.     

Combining ability in the F1 and F2 generations of diallel cross in hexaploid wheat (Triticum aestivum L. em. Thell)

The F(1) and F(2) progenies of a ten-parent diallel cross (excluding reciprocals) of hexaploid wheat (Triticum aestivum L. em. Thell) were analyzed for combining ability for quantitative and quality traits. The results indicated significant differences among the parents for general combining ability (gca) and crosses for specific combining ability (sca) for all the characters studied. The gca and sca components of variance were significant for all the traits. However, the gca component of variance was predominant indicating the predominance of additive gene effects for the traits studied. Among the parents Durgapura 65, HD 2285, Lok-1, Raj 1972 and HD 2329 were the best general combiners for grain yield and average to high combiners for tillers per plant, grain yield per spike, grains per spike and 1000-grain weight. The best specific crosses for grain yield were Sonalika x WH 157, HD 2428 x Durgapura 65, Durgapura 65 x Sonalika, HD 2428 x Lok-1 and CPAN 3004 x Raj 1972. The parent Raj 1972, Lok-1 and HD 2285 were the best general combiners for grain yield and protein content, however, Raj 3077 was the best general combiner for protein content. The most suitable specific crosses for protein content were HD 2329 x HD 2285, HD 2428 x Raj 1972 and CPAN 3004 x WH 157. Most of the specific crosses for grain yield as well as protein content involved high x average, average x average and average x poor general combiners. To ensure further increase in grain yield along with high protein, combinations of desirable yield components is advocated. Inclusion of F(1) hybrids showing high sca and having parents with good gca, into multiple crosses and/or bi-parental mating, or diallel selective mating could prove a worthwhile approach for further improvement of grain yield in bread wheat.     

玉米空间诱变后代SP4选系配合力效应分析

利用返回式卫星“实践八号”搭载3份玉米自交系08-641、RP125和18-599, 从SP4代中选出多个诱变系按不完全双列杂交设计配制杂交组合, 在四川和云南两个环境条件下进行种植鉴定。配合力分析结果表明, 3份玉米自交系经空间诱变后各性状的配合力发生不同程度的变化, 同组诱变系材料在四川和云南两种环境条件下的配合力表现存在较大差异, 且表现配合力差异的性状不同。诱变系C03的穗长、穗行数、行粒数和单株产量4个性状一般配合力(General combining ability, GCA)在该组试验中的正向效应值均表现为最大, 且显著高于基础材料08-641, 可能具有较大育种潜势; 诱变系C01和C04部分产量构成性状的GCA显著高于对照, 但单株产量GCA表现不明显, 需在育种中加以改良利用; 诱变系C06、R18和S22所配杂交组合在产量及产量构成性状上的特殊配合力(Specific combining ability, SCA)表现较优, 这些结果为玉米杂交种的选育提供了重要参考。