用胚囊和胚的整体解剖法研究玉米的胚胎发育

目前玉米杂种优势在生产上的利用是越来越广泛了。玉米杂种优势在生产上的利用主要是以推广双交种和单交种的形式出现。而配制双交和单交种需要选取配合力高的自交系,才会产生出在经济性状上优良的双交种及单交种。但是测定自交系的配合力用田间测交的方法,工作是很繁重的,而且很费时间。有报道指出有杂种优势的玉米杂种胚胎发育的速度比自交系要快。表现在胚的分化速度上,胚叶形成的速度上,以及胚的大小和重量上,甚至还表现在成熟籽粒的重量上。因     

NaCl胁迫对不同耐盐性玉米自交系萌动种子和幼苗离子稳态的影响

盐胁迫影响植物组织的离子分布,不同品种间存在差异。以玉米耐盐自交系81162和8723及盐敏感自交系P138为材料,研究了不同浓度(0、60、140、220 mmol/L)Na Cl胁迫下萌动期种子和幼苗的不同部位中Na+、K+、Ca2+含量以及K+/Na+和Ca2+/Na+比值的变化,旨在探讨不同自交系耐盐性差异的原因。结果表明,在萌动种子中,3个玉米自交系中的Na+积累量表现为种皮胚胚乳,K+累积表现为胚种皮胚乳;幼苗中,Na+积累表现为根茎叶。随着Na Cl浓度的增加,3个玉米自交系萌动种子和幼苗中的Na+含量逐渐升高,但是萌动种子中耐盐自交系81162和8723的Na+增加幅度小于盐敏感自交系P138,Na+含量小于盐敏感自交系P138;幼苗中耐盐自交系81162和8723的Na+增加幅度大于盐敏感自交系P138,幼苗根中Na+含量大于盐敏感自交系P138;茎叶中的Na+含量小于盐敏感自交系P138。随着Na Cl浓度的增加,萌动种子和幼苗中的K+和Ca2+含量逐渐降低。K+离子在耐盐自交系81162和8723萌动种子和幼苗中的降低幅度小于盐敏感自交系P138;Ca2+离子在耐盐自交系81162和8723幼苗中的降低幅度小于盐敏感自交系P138;而在萌动种子中3个自交系Ca2+的流失差异不大。耐盐自交系81162和8723萌动种子和幼苗中K+含量都大于盐敏感自交系P138。耐盐自交系81162和8723的萌动种子和幼苗根中Ca2+含量都大于盐敏感自交系P138;幼苗叶片中则小于盐敏感自交系P138。萌动种子和幼苗中K+/Na+和Ca2+/Na+均随着Na Cl浓度的升高而降低,K+/Na+比值表现为耐盐自交系81162和8723大于盐敏感自交系P138。耐盐自交系81162和8723通过调节离子平衡维持萌动种子和幼苗中较高的K+/Na+比值从而提高耐盐性。     

测交与回交例题解析

测验杂交,简称测交,是杂交F_1跟隐性亲本纯合体的交配。在核遗传实验中,利用测交可以准确地测定某一杂交子代的基因型,故是遗传学上广泛使用的一种重要试验。在育种工作中,系指自交系与测交种(品种、自交系或单交种)的交配,以测定配合力的杂交。     

玉米雄性不育类型若干特性的初步研究

研究结果表明,将原有的玉米雄性不育系转化为新的不育系,回交4—5代,新不育系绿叶面积、光合势略高于保持系,植株外貌极为相似,可供育种工作利用。在净同化率和产量方面,同组合的不育单交种较可育单交种为高。同时,通过对不育系育性的鉴定,初步认为威西137、维尔44、威153和瓦8等4个自交系具有较高的恢复能力。     

中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的关系研究

在玉米单交种育种中 ,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以 1 7个优良玉米自交系为亲本 ,按照双列杂交配组合 ,利用 RAPD技术分析了 1 7个自交系的多态性以及 RAPD标记与 9个重要农艺性状 (包括产量 )的关系。基于 RAPD标记计算的相似系数聚类将 1 7个自交系分为 5个类群 ,经分析与系谱亲缘关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的 ,与聚类前比较 ,聚类后平均遗传距离与平均产量、平均特殊配合力的相关系数显著提高 ,类间平均产量高于类内平均产量。RAPD技术可揭示优良玉米自交系的系谱亲缘关系 ,将自交系划分成不同的类群 ,从而为选择类间自交系杂交 ,进行亲本选配和分子标记辅助育种提供一种方法。     

中国17个优良玉米自交系的分子标记杂合性及其与杂交种性状的 …

在玉米单交种育种中,鉴定高产杂交种和具有优良特性的自交系是一个重要的问题。研究以１７个优良玉米自交系为亲本,按照双列杂交配组合,利用ＲＡＰＤ技术分析１７个自交系的多态性以及ＲＡＰＤ标记与９个重要农艺性状（包括产量）的关系。基于ＲＡＰＤ标记计算的相似系数聚类将１７个自交系分为５个类群,经分析与系谱关系基本一致。杂交种性状及其特殊配合力与亲本间的遗传距离是高度相关的,与聚类前比较,聚类后平均遗传距离与     

等离子束玉米自交系选育初探

2 .0Me氦离子束不同的剂量注入玉米自交系 478干种子胚 ,其结果表明 ,玉米自交系 478以 1× 10 1 6 cm2的剂量处理后 ,其后代主要性状变异明显。出现了比亲本早熟 2 3天的自交系和籽粒产量特高的自交系。并初步组配、筛选出配合力强、抗逆性强的杂交新组合。     

玉米杂种优势与种子萌发时的胚重和RNA、DNA含量的相关性

对10个具优势的玉米单交种及其亲本进行试验。取种子开始萌发的胚(包括胚芽、胚轴和胚根)进行RNA、DNA和全氮的定量测定。做了胚胎细胞数的计测和328单交种及其亲本胚胎石蜡切片的观察。试验结果表明,优势杂种胚中RNA、DNA和全氮含量均比其亲本胚中的含量高。计测胚胎细胞数也表明,杂种比其亲本胚胎的细胞数有明显的增多。从328单交种及其亲本的石蜡切片观察看出,杂种胚胎组织分化提前,器官分化清晰,发育得好。     

利用组织培养技术选育玉米抗小叶斑病突变体

大叶斑病和小叶斑病是玉米最严重的病害,选育抗大、小叶斑病优良自交系及单交种是提高玉米产量的重要措施。Ｇｅｎｇｅｎｂａｃｈ等以玉米Ａ６１９ｃｍｓＴ愈伤组织为材料,筛选出对小叶斑病毒素具有抗性的愈伤组织与再生植株［１,２］,开辟了玉米抗病育种的新途径。...     

基于决策树的红色籽用西瓜数据挖掘

利用Clementine软件提供的决策树C5．0算法,探索红色籽用西瓜自交系多个数量性状之间的相互制约关系。初步建立了单瓜种子重决策树模型,预测精度达到68％。可据此模型对红籽瓜自交系的各经济性状进行定量分析,为育种生产者进行优良自交系和亲本选配提供决策。     

Genetic control of embryo lethality in crosses between common wheat and rye

The phenotypic manifestation and genetic control of embryo lethality observed in crosses between common wheat and rye were studied. It was found that crosses between common wheat and inbred self-fertile rye lines L2 and 535 gave rise to ungerminating grains, in which the development and differentiation of the hybrid embryo are arrested. Study of the degree of embryo development in the hybrid grains obtained by crossing common wheat varieties with inbred rye lines L2 and 535 showed that genotypes of the parents affected the ratio between undifferentiated embryos of various sizes. Analysis of this trait was performed by test crosses according to a novel pedigree program with the use of interlinear hybrids and a set of fourth-generation hybrid recombinant inbred lines. Rye line L2 was shown to bear the Eml (Embryo lethality) gene, which terminates the development of the hybrid embryo in amphihaploids. The suggestion of complementary interaction between wheat and rye genes during formation of a "n ew" character in wheat-rye F1 hybrids is discussed. A method of detecting an allele not complementary to the rye Eml allele in wheat is proposed. The proposed test program allows appropriate study of the system of wheat and rye genes involved in complementary interaction in the genotype of a distant hybrid.     

Effect of Genotype on Formation of Hormonal Function of Leydig Cells during Mouse Postnatal Development

Changes in in vitro testosterone production by Leydig cells induced by chorionic gonadotropin, dibutyryl-cAMP, and pregnenolone have been studied during postnatal development of four inbred mouse strains BALB/c, PT, CBA/Lac, and A/He, with contrast hormonal activity of testes in sexually mature males. The interlinear differences significantly change with age of the males by all studied indices indicating genotype-dependent formation of hormonal activity of Leydig cells during postnatal development. Coordinated interlinear variability between all indices of Leydig cells reactivity has been established for each studied period of postnatal development. Hence, we have established coordinated interlinear genetic variability of hormonal function of Leydig cells, which was confirmed by considerable changes in it during postnatal development at puberty. Definitive genotypic differences in hormonal activity of Leydig cells appeared by late pubertal and early postpubertal development (day 60) and coincided with termination of morphological differentiation of Leydig cells and appearance of the differentiated cell population.     

Effect of genotype on hormonal function formation of Leydig cells during mouse postnatal development

Changes in in vitro testosterone production by Leydig cells induced by chorionic gonadotropin, dibutyryl-cAMP, and pregnenolone have been studied during postnatal development of four inbred mouse strains BALB/c, PT, CBA/Lac, and A/He, with contrast hormonal activity of testes in sexually mature males. The interlinear differences significantly change with age of the males by all studied indices indicating genotype-dependent formation of hormonal activity of Leydig cells during postnatal development. Coordinated interlinear variability between all indices of Leydig cells reactivity has been established for each studied period of postnatal development. Hence, we have established coordinated interlinear genetic variability of hormonal function of Leydig cells, which was confirmed by considerable changes in it during postnatal development at puberty. Definitive genotypic differences in hormonal activity of Leydig cells appeared by late pubertal and early postpubertal development (day 60) and coincided with termination of morphological differentiation of Leydig cells and appearance of the differentiated cell population.     

Genetic Control of Embryo Lethality in Crosses between Common Wheat and Rye

The phenotypic manifestation and genetic control of embryo lethality observed in crosses between common wheat and rye were studied. It was found that crosses between common wheat and inbred self-fertile rye lines L2 and 535 gave rise to ungerminating grains, in which the development and differentiation of the hybrid embryo are arrested. Study of the degree of embryo development in the hybrid grains obtained by crossing common wheat varieties with inbred rye lines L2 and 535 showed that genotypes of the parents affected the ratio between undifferentiated embryos of various sizes. Analysis of this trait was performed by test crosses according to a novel pedigree program with the use of interlinear hybrids and a set of fourth-generation hybrid recombinant inbred lines. Rye line L2 was shown to bear the Eml (Embryo lethality) gene, which terminates the development of the hybrid embryo in amphihaploids. The suggestion of complementary interaction between wheat and rye genes during formation of a “new” character in wheat-rye F₁ hybrids is discussed. A method of detecting an allele not complementary to the rye Eml allele in wheat is proposed. The proposed test program allows appropriate study of the system of wheat and rye genes involved in complementary interaction in the genotype of a distant hybrid.__________Translated from Genetika, Vol. 41, No. 8, 2005, pp. 1075–1083.Original Russian Text Copyright © 2005 by Tikhenko, Tsvetkova, Voylokov.     

Detection of the interstrain polymorphism of heart muscle proteins in mice using two-dimensional electrophoresis

Cardiac muscle proteins of four inbred murine strains were analyzed by one- and two-dimensional electrophoresis. Of those, 27 and 161 protein fractions were characterized in terms of molecular mass and relative electrophoretic mobility. The protein fractions were identified as corresponding to creatine phosphokinase, myoglobin and an albumin-like protein. Six polypeptides characterized by interlinear polymorphism were identified.     

Interlinear differences in generative function formation in pubescence of male mice

The formation of generative function in pubescence is studied in males of three inbred mice lines BALB/cLac, CBA/Lac, and PT. From days 35 through 60 of life every 5 days the amount of sperm cells and the quantity of abnormal heads of spermatozoa in males are calculated in both epididymises and the morphometry of the testicles, epididymises, and seminal vesicles is carried out. Interlinear deviations in the pubertal dynamics of the parameters of spermatogenesis and the morphometric indexes are determined, indicating a weak spermatogenesis process in males of CBA/Lac in comparison with males from the other lines. Males from the line CBA/Lac are characterized by a low amount of epididymal spermatozoa combined with low frequency of abnormal spermatozoon heads; these traits can be considered as a compensatory process that increases fertility. By the end of the period, i.e., on days 55–60 of life, the males of all three inbred mice lines have not reached the definitive level in the number of epididymal spermatozoa; the weight of the testicles, epididymise, and seminal vesicles; and body weight. Thus, in laboratory mice, the beginning of reproductive activity is not connected with these reproductive indexes reaching the definitive level. The results of the study show that in adult mature males of laboratory mice the interlinear deviations in generative function emerge in the pubertal period and persist thereafter.     

Contributions of heterosis and epistasis to hybrid fitness

Early-generation hybrid fitness is difficult to interpret because heterosis can obscure the effects of hybrid breakdown. We used controlled reciprocal crosses and common garden experiments to distinguish between effects of heterosis and nuclear and cytonuclear epistasis among morphotypes and advanced-generation hybrid derivative populations in the Piriqueta caroliniana (Turneraceae) plant complex. Seed germination, growth, and sexual reproduction of first-generation hybrids, inbred parental lines, and outbred parental lines were compared under field conditions. Average vegetative performance was greater for hybrids than for inbred lines, and first-season growth was similar for hybrids and outbred parental lines. Hybrid survival surpassed that of inbred lines and was equal to or greater than outbred lines' survival, and more F(1) than parental plants reproduced. Reductions in hybrid fitness due to Dobzhansky-Muller incompatibilities (epistasis among divergent genetic elements) were expressed as differences in vegetative growth, survival, and reproduction between plants from reciprocal crosses for both F(1) and backcross hybrid generations. Comparing performance of hybrids against parental genotypes from intra- and interpopulation crosses allowed a more robust prediction of F(1) hybrids' success and more accurate interpretations of the genetic architecture of F(1) hybrid vigor.     

Floral biology and pollen viability of parental lines of onion hybrids

Parental lines (inbred and hybrid male-sterile lines and inbred pollinators) of prospective F, hybrids from the NVRS spring-sown bulb onion breeding programme were examined to study their floral biology and aspects of pollination under glasshouse conditions. Inbreeding depression occurred in both pollinator and male-sterile inbreds in terms of reduced flower numbers per umbel and a greater proportion of defective pistils. Male-sterile and male-fertile lines differed in their stigma and style characteristics and pattern of development. At flower opening, the styles of male-sterile lines were longer and the stigmatic knob became receptive relatively sooner. The inbred male-sterile line II/3 ms appeared to have a reduced receptive area on its stigmatic knob and remained receptive for a relatively shorter period. Individual lines differed for time of flowering, nectar content and its sugar concentration, and in their effectiveness as male and female parents as judged from pollen tube growth down the style in specific pairings. Assessment of pollen viability using the fluorescein diacetate test did not correlate with assessments based on pollen grain germination and subsequent growth down the style, perhaps as a result of differential receptivity in the inbred lines tested. These results are discussed in relation to future hybrid seed production.     

Analysis of natural allelic variation of Arabidopsis seed germination and seed longevity traits between the accessions Landsberg erecta and Shakdara, using a new recombinant inbred line population

Quantitative trait loci (QTL) mapping was used to identify loci controlling various aspects of seed longevity during storage and germination. Similar locations for QTLs controlling different traits might be an indication for a common genetic control of such traits. For this analysis we used a new recombinant inbred line population derived from a cross between the accessions Landsberg erecta (Ler) and Shakdara (Sha). A set of 114 F9 recombinant inbred lines was genotyped with 65 polymerase chain reaction-based markers and the phenotypic marker erecta. The traits analyzed were dormancy, speed of germination, seed sugar content, seed germination after a controlled deterioration test, hydrogen peroxide (H2O2) treatment, and on abscisic acid. Furthermore, the effects of heat stress, salt (NaCl) stress, osmotic (mannitol) stress, and natural aging were analyzed. For all traits one or more QTLs were identified, with some QTLs for different traits colocating. The relevance of colocation for mechanisms underlying the various traits is discussed.     

Manifestation of heterosis during early maize (Zea mays L.) root development

Heterosis is typically detected in adult hybrid plants as increased yield or vigor compared to their parental inbred lines. Only little is known about the manifestation of heterosis during early postembryonic development. Objective of this study was to identify heterotic traits during early maize root development. Four German inbred lines of the flint (UH002 and UH005) and dent (UH250 and UH301) pool and the 12 reciprocal hybrids generated from these inbred lines were subjected to a morphological and histological analysis during early root development. Primary root length and width were measured daily in a time course between 3 and 7 days after germination (DAG) and displayed average midparent heterosis (MPH) of 17–25% and 1–7%, respectively. Longitudinal size of cortical cells in primary roots was determined 5 DAG and displayed on average 24% MPH thus demonstrating that enlarged primary roots of hybrids can mainly be attributed to elongated cortical cells. The number of seminal roots determined 14 DAG showed on average 18% MPH. Lateral root density of all tested hybrids was determined 5 DAG. This root trait showed the highest degree of heterosis with an average MPH value of 51%. This study demonstrated that heterosis is already manifesting during the very early stages of root development a few days after germination. The young root system is therefore a suitable model for subsequent molecular studies of the early stages of heterosis manifestation during seedling development.