雌雄同株黄瓜单性结实性主基因+多基因混合遗传分析

以雌雄同株黄瓜强单性结实自交系'6457'和非单性结实自交系'6426'为亲本,建立了5世代联合群体(P1、P2、F1、F2、F2∶3),采用植物数量性状主基因+多基因混合遗传模型对群体的单性结实性进行多世代联合分析.结果表明:雌雄同株黄瓜单性结实性表现为不完全显性遗传,符合D-2遗传模型,受1对加性主基因+加性-显性多基因控制.主基因加性效应值为14.7,多基因加性效应值为20.9,多基因显性效应值为25.8.F2的遗传率为56.6%,F2∶3的遗传率为48.7%.因此,对雌雄同株黄瓜单性结实性的遗传改良,可选择强单性结实性材料,通过杂交、回交转移主基因,达到选育强单性结实性材料目的.     

水稻核不育系4个柱头性状的遗传分析

为改良水稻(Oryza sativa)核不育系柱头性状提供遗传信息, 调查了粳型核不育系7001S、籼型核不育系Z913S及其杂交、自交获得的F₁、F₂和F_2:3群体的4个柱头性状, 分析了4个性状间的相关性, 并利用主基因+多基因遗传模型对2个世代4个性状进行遗传分析。结果表明, 4个性状两两间呈极显著正相关, 相关系数介于0.274-0.897之间。除F_2:3群体中花柱长度和柱头外露率分别表现出受2对加性-显性主基因和1对负等效加性-显性主基因+多基因控制外, F₂和F_2:3群体的柱头长度、花柱长度、柱头-花柱总长度以及柱头外露率均表现出受2对主基因和多基因控制, 且F_2:3群体中控制花柱长度的主基因表现出加性-显性效应, 其余均表现出加性-显性-上位性效应。2个世代中4个性状均以主基因遗传为主。     

黄瓜雄花性状的遗传分析

为了解黄瓜雄花花器的遗传特性,该研究以雄花器官较小的华南型黄瓜二早子为母本,花器较大的加工型黄瓜NC-76为父本,构建4世代遗传群体,并采用多世代联合分离分析方法,分析黄瓜雄花花器性状的遗传特性。结果表明:分离群体的雄花花梗和花冠长2个性状均表现为单峰分布,表明两性状为数量性状且有主基因控制;花梗长性状符合2对完全显性主基因+加性-显性多基因(E-5)模型,花冠长性状符合2对加性-显性-上位性主基因+加性-显性-上位性多基因(E-1)模型;控制花梗长性状的两对主基因的加性效应相等,为0.573,多基因的加性效应和显性效应值相差不大,且均为负向;控制花冠长度性状的2对主基因的加性效应均为0,显性效应分别为-0.226和-0.472,在上位性作用中以加性×加性和显性×显性互作为主,多基因以显性效应为主,正向显性效应值为0.613,大于负向的加性效应值。花梗和花冠长度两个性状在F2群体中主基因遗传率分别为61.04%和69.60%,多基因遗传率均为0。由此看出黄瓜雄花花器性状为数量遗传,遗传率相对较高。该研究结果显示在黄瓜杂交育种中对花器大小选择可以在较早世代选择。     

黄瓜苗期低温弱光下MDA含量主基因-多基因联合遗传分析

选取耐低温弱光性不同的2份黄瓜材料9507、9517及其配制的BC1、BC2、F1、F2等6个世代,进行低温弱光处理,每天光照处理7.5 h,强度为30 μmol·m-2·s-1,约合2 000 lx,白天12℃,晚上8℃,共处理14 d.运用主基因-多基因联合遗传模型方法研究丙二醛(MDA)含量的遗传规律,并估算遗传参数.结果表明MDA含量的遗传受2对加性-显性-上位性主基因+加性-显性多基因控制,2对主基因的加性效应均为负向效应,其显性效应也均为负向,差异不大.总加性效应与总显性效应均为较大的负向效应.分离世代中,主基因的遗传率均比多基因的遗传率高,环境方差对表型方差的影响占有绝对优势,即低温弱光条件下环境对MDA含量的遗传起很大作用,对于这个性状适于晚代选择.     

烤烟CMV抗性的主基因 多基因混合遗传模型分析

以高抗CMV的烤烟品种台烟8号为母本(P1),以高感CMV的烤烟品种NC82为父本(P2),在2个不同的时间环境下构建P1、P2、F1和F24个世代群体,在植株不同生长时期进行CMV病害鉴定。运用植物数量性状"主基因+多基因"混合遗传模型分析方法对该世代群体的CMV抗性进行联合分析。结果表明,在温室环境中,苗期和成株期鉴定CMV抗性遗传都符合E1模型,即由2对加性-显性-上位性主基因+加性-显性多基因混合控制,主基因遗传率分别是37.11%、57.76%;在大田环境中,苗期抗性鉴定符合加性-显性-上位性多基因模型(C0),多基因遗传率为26.86%,而成株期鉴定属于2对主基因+多基因模型(E2),主基因遗传率为36.57%。研究表明,由于植物抗性基因的表达具有时空性,台烟8号对CMV的抗性遗传在不同的时间和环境具有一定的差异;但随着植株的生长,抗性遗传趋于稳定,在成株期时,2个不同的环境均表现为2对主基因+多基因控制,所以对烤烟CMV抗性品种选育和改良要以主基因为主,同时注重环境的影响。     

黄瓜苗期低温弱光下耐低温性主基因-多基因联合遗传分析

选取耐低温弱光性不同的2份黄瓜材料9507、9517及其配制的BC1、BC2、F1、F2等6个世代,进行低温弱光处理,每天光照处理7.5h,强度为30μmol/m2.s,约合2000lx,白天12℃,晚上8℃,共处理14d。运用主基因-多基因联合遗传模型方法研究耐低温性的遗传规律,并估算遗传参数。结果表明,耐低温性的遗传受2对加性主基因+加性-显性多基因控制,F1平均值略低于中亲值,主基因的遗传率为62.871%～79.310%,多基因的遗传率为3.448%～7.792%,主基因+多基因的遗传率为74.026%～82.759%,环境方差占表型方差的比率为17.241%～25.974%。即低温弱光条件下环境对耐低温性的遗传起很小作用,对于这个性状适于早代选择。     

萝卜不同抗源对黑腐病抗性的遗传分析

不同抗病基因的挖掘是作物持久抗性遗传改良的基础。本研究利用2份抗黑腐病(Xanthamonas campestris pv.campestris)萝卜(Raphanus sativus L.)材料(KB10Q-22、KB10Q-24)和1份感病材料(KB10Q-33)构建了2个F2群体,采用苗期剪叶+喷雾法接种黑腐病菌Xcc8004进行抗病性鉴定。应用P1、P2、F1、F24个世代的数量性状主基因+多基因混合遗传分析方法,研究了萝卜2个不同抗源抗黑腐病的遗传规律,结果表明2份材料的遗传规律不同。以KB10Q-22为母本的F1植株表现为抗病,其遗传模型为E_0模型,即2对加性-显性-上位性主基因+加性-显性-上位性多基因模型;而以KB10Q-24为母本的F1植株表现为感病,其遗传模型为D_0模型,即1对加性-显性主基因+加性-显性-上位性多基因模型。两群体主基因遗传率分别为87.73%和55.64%,抗性遗传以主基因为主。     

黄瓜抗黑星病不同基因源的遗传分析

基于苗期人工接种鉴定结果,获得2份抗黑星病黄瓜材料(HX1,Cucumis sativus var.sativus,DI=5;HX5,C.sativusvar.xishuangbannesis,DI=38.7)和1份感病材料(HX8,C.sativus var.sativus,DI=80)。利用上述3份材料构建了2个组合(HX1×HX8,HX5×HX8)的6世代群体(P1、P2、F1、F2、B1和B2),并分别进行黑星病苗期人工接种鉴定。采用主基因+多基因联合遗传分析方法进行遗传分析,结果表明2份材料抗黑星病的遗传规律不同。组合HX1×HX8的F1单株表现为抗病,而组合HX5×HX8的F1单株基本表现为感病。HX1对黑星病的抗性符合两对加性-显性-上位性主基因+加性-显性多基因混合遗传模型(E_1模型),HX5的抗性遗传符合加性-显性多基因模型(C模型)。在组合HX1×HX8中,两对主基因的加性效应均大于显性效应,B1、B2和F2群体的主基因遗传率分别为72.51%、98.19%和96.91%,多基因遗传率均为0,表明HX1对黑星病的抗性以主基因遗传为主;HX5对黑星病的抗性遗传以多基因的显性效应为主。     

甜瓜远缘群体果实糖含量相关性状遗传分析

以栽培甜瓜0246为母本,野生甜瓜Y101为父本,构建了P1、P2、F1、F2、B1、B26个世代,运用植物数量性状主基因+多基因混合遗传模型进行多世代联合分析,探讨了甜瓜果实糖含量相关性状的遗传特性。结果表明:果糖含量、葡萄糖含量和总糖含量遗传均受两对加性-显性-上位性主基因+加性-显性-上位性多基因模型控制(E-0),主基因在F2中的遗传率分别达到90.32%、82.42%和94.66%。蔗糖含量受一对加性主基因+加性-显性多基因模型控制(D-2),主基因在F2中的遗传率达到83.76%。甜瓜果实糖含量相关性状遗传体系中主基因具有重要作用且环境方差所占比例较小,适宜早代选择。     

辣椒果实性状主基因+多基因遗传分析

以果实性状差异较大的一年生辣椒材料C.annuum B9431(P1)和灌木辣椒材料C.frutescens H108(P2)为亲本,构建4世代群体(P1、P2、F1、F2),应用数量性状主基因+多基因混合遗传模型方法对辣椒6个果实性状进行遗传分析,为辣椒果实性状QTL定位及分子标记辅助育种研究奠定理论基础。结果表明:6个果实性状均符合2对主基因+多基因遗传模型。其中,单果重量、果实纵径、果实横径、果形指数和果肉厚度5个性状均符合E-0模型,即2对加性-显性-上位性主基因+加性-显性-上位性多基因混合遗传模型;果柄长度最佳遗传模型为E-5,即2对完全显性主基因+加性-显性多基因模型。单果重量、果实纵径、果实横径、果形指数、果肉厚度和果柄长度主基因遗传率分别为87.64%、37.67%、82.46%、94.82%、83.33%和40.00%,多基因遗传率分别为7.50%、54.56%、10.53%、0.27%、12.96%和37.78%。     

Genetic Analysis of Oil Content in Brassica napus L. Using Mixed Model of Major Gene and Polygene

The joint segregation analysis of a mixed genetic model of major gene plus poly-gene was conducted to study the inheritance of oil content in Brassica napus L. Five populations, i.e the populations of 2 parents(P₁ and P₂), F₁, F₂ and F_2:3 (derived from F₂) family, from each of the two crosses (1141B × Ken C₁-1, 32B × Ken C₁-2) were investigated. The frequency distributions of oil content in F₂ and F_2:3 family populations show characteristics of a mixed normal distribution, which indicated that the inheritance of oil content followed a major gene plus poly-gene model. Twenty-one genetic models were established, which could be classified into five types: one and two major genes, polygenes, one and two major genes plus polygenes. The most suitable genetic model could be selected using Akaike's Information Criterion and the fitness of the selected one could be examined by a set of tests. Results show that genetic model D-2 is the most fitting genetic model for the trait. In other words, oil content in oilseed rape is controlled by one additive major gene plus additive and dominance polygenes. For cross 1 (1141B × Ken C₁-1) the heritabilities of major gene and poly-genes in F₂ are 68.21% and 27.17%, respectively, and in F_2:3 are 81.70% and 16.80%, respectively. The additive effect of major gene is-1.74, which indicates that the locus of the allele in parent 1141B may decrease the oil content, but that in parent Ken C₁-1 may increase it. The additive and dominance effects of the polygenes are 1.20 and -1.93, respectively. For cross 2 (32B × Ken C₁-2) the heritabilities of major gene and polygenes in F₂ are 66.20% and 28.10%, respectively, and in F_2:3 were 81.00% and 14.90%, respectively. The additive effect of major gene was -3.74, which also indicates that the locus of the allele in parent 32B may decrease the oil content, but that in parent Ken C₁-2 may increase it. The additive and dominance effects are -1.99 and 0.93, respectively. The heritability of the major gene in F_2:3 is higher than that in F₂ in both crosses, so it would be more efficent to conduct selection in F_2:3 families for high oil content in breeding.     

The inheritance of fertility restoration in male-sterile wheat carrying cytoplasm derived from Triticum timopheevi

Summary The inheritance of the restoration of fertility in material carrying the cytoplasm of Triticum timopheevi was studied in F₂, F₃ and F₄ generations. In the material used the segregation of restoration was shown to fit the hypothesis of three major, dominant, partially dominant or additive genes each of which made a different contribution to restoration but which acted cumulatively to produce the phenotypic expression observed.From the material it was possible to extract homozygous lines carrying known combinations of these three genes which can be used as tester lines to investigate the inheritance of genes for restoration derived from other sources.     

The DefH9-iaaM-containing construct efficiently induces parthenocarpy in cucumber

Parthenocarpy (seedless fruits) is a desirable trait that has been achieved in many plant cultivars. We generated parthenocarpic cucumber fruits by introducing the chimeric DefH9-iaaM construct into the cucumber genome using an Agrobacterium tumefaciens-mediated protocol. The construct consists of the DefH9 promoter from Antirrhinum majus and the iaaM coding sequence from Pseudomonas syringae. Transgenic plants were obtained from nine independent transformation events: half of these were tetraploid and did not produce seeds following self-pollination, while the remaining half were capable of displaying parthenocarpy in the subsequent reproductive generation. Of the fruits produced by the transgenic lines, 70–90% were parthenocarpic. The segregation of the marker gene in the transgenic T₁ progeny indicated single gene inheritance. The seed set in the transgenic lines and their F₁ hybrids was lower than in the non-transgenic control plants. Some of the methodological details and the practical significance of the results are discussed. This paper is dedicated to Prof. Juergen Grunewaldt from Hannover on the occasion of his retirement.     

Genetics of resistance to Fusarium oxysporum f.sp. cucumerinum races 1 and 2 in cucumber line Wisconsin-2757

The mode of inheritance of resistance to Fusarium oxysporum f.sp. cucumerinum races 1 and 2 in Wisconsin-2757 (WI-2757), a gynoecious cucumber (Cucumis sativus L.), was determined by analysing segregation of F₁, F₂ and BC₁ populations of crosses with susceptible cultivar Straight-8. Resistance to either race 1 or race 2 in WI-2757 was conferred by a single dominant gene. In allelism tests, resistance to either race in WI-2757 was determined by the gene Fcu-1, which also confers resistance in line SMR-18.     

Inheritance of the red color in tilapias

The inheritance of the red color was studied in two different varieties of tilapia which are both considered as hybrids of Oreochromis mossambicus. Crosses between red tilapia from the Philippines (PRT) and Sarotherodon galilaeus, or Oreochromis aureus gave a 1:1 ratio of red: normal and crosses between F₁ black fish gave only black offspring. On the other hand crosses between the F₁ red fish gave a 3:1 ratio of red:black and crosses between F₁ red and black offspring gave a 1:1 ratio. These results lead to the conclusion that red color is dominant over the normal black color and controlled by a single autosomal gene (R). A unique phenotype named albino with black eyes was observed among offspring of PRT and a presumed model of inheritance of this trait is proposed. Genetic analysis of a second variety of red tilapia (derived from an unknown origin) showed the following results: crosses between parents and between their F₁ offspring consistently gave 100% red fish and crosses between this red tilapia and Oreochromis aureus gave 100% black offspring. The crosses between red and black F₁ of these last two crosses gave a 1:1 ratio and crosses carried out between the black F₁ offspring gave a 1:3 ratio of red:black. It may be concluded from these results that the black color is dominant in this strain and that this color is controlled by a single autosomal gene (B). The presumed mode of action of the dominant gene (R) as well as of the recessive gene (b) are discussed.     

Genes for Dwarfness in Wheat, TRITICUM AESTIVUM L

The genetic control of plant height was studied in crosses of four spring wheats involving the standard height variety Ramona 50 and short-statured selections Olesen, D6301, and D6899. Data from parent, F₁, F₂, and F₃ populations indicated that four independently segregating loci account for most of the differences among the four varieties. Two major genes of a highly recessive nature condition reduced height in Olesen and the Norin 10 derivative D6301. Olesen also carries a third dwarfing gene which is partially dominant in its effects over genes for tallness. This gene, or a gene that acts in a similar manner, is also present in the standard height variety Ramona 50. Dwarfing in D6899, a derivative of Tom Thumb, is controlled primarily by a single gene with mainly additive effects which is not present in any of the other three varieties.

Genetic components estimated from generation means (parental, F₁, F₂, F₃, and backcross) indicated that additive gene effects were the major component of variation in four of the six crosses, and of similar magnitude to dominance effects in another cross. The primary source of genetic variation in the cross Olesen x D6899 was due to epistasis with both additive x additive and dominance x dominance effects of major importance. The results of the generation mean analyses were consistent with the models for major-gene control of plant height based on segregation patterns.

     

Genetic analysis of heat shock proteins in maize

A genetic analysis of heat shock protein (HSP) synthesis was performed in seedling leaf tissue of two maize inbred lines, their F₁ hybrid and F₂ progeny. Protein synthesis following a high temperature treatment was visualized by [³⁵S]-methionine in vivo labelling and two-dimensional gel electrophoresis. The parental lines' HSP synthesis patterns revealed both qualitative and quantitative polymorphisms implicative of differences in HSP structural genes and regulatory factors. The F₁ hybrid HSP profile indicated that synthesis of all parental HSPs conformed to dominant inheritance patterns, including complete dominance, over-dominance and co-dominance. Alleles for six low-molecularweight HSPs in F₂ progeny assorted according to typical 31 Mendelian ratios for dominant gene expression. There is evidence for unlinked gene loci of four different HSP gene pairs, but data for three other HSP gene pairs were inconclusive, perhaps reflecting linkage for one pair and complex regulatory factor interactions for the other two pairs of genes. These results clearly indicate the existence of genetic variability in HSP synthesis and emphasize the potential of partitioning their roles in thermal tolerance using genetic and molecular analyses.     

Inheritance of downy mildew resistance, β-1,3-glucanases and peroxidases in pearl millet [Pennisetum glaucum (L.) R. Br.] crosses

The inheritance of resistance to downy mildew disease and the defense-related enzymes β-1,3-glucanase and peroxidase was studied in crosses of pearl millet using a generation-mean analysis. The study material comprised six generations (susceptible and resistant parents, F₁, F₂, BC₁ and BC₂) in three crosses. Seedlings from these generations were inoculated with the downy mildew pathogen Sclerospora graminicola and disease incidence was recorded. Analysis of constitutive levels of β-1,3-glucanase and peroxidase in the seedlings of different generations indicated that the resistant populations showed higher enzyme activities, while lower activities of the enzymes were recorded in the susceptible populations. In the generation-mean analysis, the significance of scaling tests revealed the existence of non-allelic interactions in the inheritance of resistance to downy mildew as well as with the enzymes. Among the gene effects, both additive and dominant effects were significant. All the non-allelic interaction effects were significant in the crosses. Studies on the isozyme patterns of the enzymes substantiated the results of the disease-incidence experiments in most of the generations. The results indicated that the inheritance of downy mildew disease resistance and the expression of β-1,3-glucanase and peroxidase in pearl millet is not only under the control of additive and dominant genes but are also governed by complex non-allelic interactions. Received: 30 April 2000 / Accepted: 17 October 2000     

Study of the inheritance of sex expression in the cucumber. The interaction of major genes with modifying genetic and non-genetic factors

Summary Two major genes and a complex of polygenes affecting sex expression inCucumis sativus L. as well as their interaction with some nongenetic factors were investigated in the present study. The genetic factorst was found to affect sex by inducing a shift of the predetermined flowering pattern of this plant, in the direction of its base. As this pattern is composed of a staminate stage followed by a mixed (staminate-pistillate) stage and a pistillate stage, a double dose ofst will induce a change from the normal monoecious sex expression (to absolute gynoecism.The second major gene studied,m, known previously to control sex in the individual flower (m/m—andromonoecious,M—monoecious), also interacts with factors affecting the flowering pattern by inducing male tendency.Using an ordinary commercial monoecious stock additional modifying factors for sex expression were demonstrated, by eight generations of selection for high (in male direction) and for low (in female direction) node number to the first pistillate flower. A comparison of the means and frequency distributions of node number of the two selected lines, their F₁ and F₂, indicated polygenic control of this character.It was found that two non-genetic factors, day length and gibberellic acid (GA), may mimic the genetic factors for sex expression. Furthermore, evidence was presented, indicating that this sex controlling ability of GA and the modifying genes may be based on physiological conditions common to those two genetic and nongenetic factors.The overall mechanism of sex control in the cucumber and in other plants was discussed and a hypothetic model for the evolution of dioecism in flowering plants was proposed.