重庆温光型小麦雄性核不育系C49s小孢子发生和发育的细胞学研究

作者对重庆温光型小麦雄性核不育系“C4 9s”、普通小麦“6 9”及不育系“C4 9s 87”与普通小麦“94 6 4”的杂种F1代雄性器官进行切片观察 ,发现其雄配子发育从花粉母细胞减数分裂间期到二分孢子时期绒毡层差异不大 .在减数分裂前期Ⅱ到中期Ⅱ ,不育系绒毡层细胞部分呈双核、三核增大细胞 ,部分出现核解体 ,而普通小麦“6 9”与“C4 9s 87/94 6 4”的杂种F1代中没有出现该现象 .不育系绒毡层细胞比可育系迟解体 .从单核早期开始 ,不育系小孢子发育不正常 ,表现为小孢子收缩变形 ,无核或有核细胞质稀薄 ,细胞核不能定向移动到萌发孔的对侧 .“C4 9s”败育的原因可能与绒毡层发育及液泡的动态性有关 .败育的高峰为单核期 .     

小麦雌性不育遗传的初步分析

为了探明小麦雌性不育的遗传规律,以小麦雌性不育系fs与育性正常的小麦品种或种的杂交一代和二代为材料,对其雄性育性和雌性育性进行了两年的观察,其杂种一代和二代的雄性育性正常,雌性育性在一代正常,二代多数组合出现1 4或1 16的雌性不育株,初步认为小麦雌性不育依试验亲本选材的不同表现为一对或两对隐性基因的遗传,雌性不育的表达可能涉及到两对主效基因的参与并且受环境的修饰.     

小麦雌性育性双向极端群体QTL定位策略初探

在极端不育群体中计算重组频率(c值)初步筛选QTL位点的基础之上,利用普通小麦中育性正常的良种藁城8901(P1)与雌性不育系XND126(P2)杂交F2群体中的189株隐性极端不育株和63株极端可育株组成的双向极端群体为定位群体,构建了连锁图,分析定位了小麦雌性育性位点taf1,获得了与F2平衡群体相同的定位位点.分析发现与taf1位点连锁较紧密的标记,其c值较小.利用极端群体的策略能快速有效的定位小麦雌性育性QTL在染色体上的位置.     

雄性不育和雄性能育小麦花药和花粉发育的细胞形态学观察

本工作是小麦雄性不育杂种优势利用研究项目的一部分。从细胞形态学的角度,研究小麦细胞质雄性不育系及其保持系花药和花粉的发育,为探索雄性不育性的机理提供资料。 发应用石腊切片法,对小麦“早熟1号”和“北京8号”细胞质雄性不育系及其保持系花药的发育过程进行了观察,得到如下的结果: (1)不育系花粉的败育,在发育的各个时期都发生,但败育的关键时期是在小孢子发育后期,具大液泡的小孢子不能进入配子体发育阶段。 (2)不育系花药和花粉的发育,在小孢子发育早期以前,百分之九十以上与保持系相似,是正常的,少数表现异常而导致败育。异常现象有:①药室合并;②小孢子母细胞解体,绒毡层正常发育,③小孢子母细胞互相粘连形成多核原生质团;④解体的小孢子母细胞与绒毡层融合形成多核原生质团;⑤药室中除正常发育的小孢子母细胞或小孢子外,还出现异常的巨型细胞;⑥绒毡层提前在小孢子发育早期解体,并形成多核的原生质团;⑦绒毡层肥大生长。     

小麦雌性不育基因的微卫星标记定位

以普通小麦新601×雌性不育小麦XND126的F2群体作为育性调查以及基因标记群体.通过对育性基因的分析,确定在此组合中雌性不育基因由1对主效基因控制;结合混合分组分析法(Bulk Segregant Analysis,BSA),首次对小麦雌性不育基因进行了SSR分子标记,通过对一千对微卫星引物的筛选,确定微卫星引物cfd36标记与主效基因连锁,遗传距离为20.2cM.     

苎麻雄性不育系与保持系花药发育的比较观察

 为研究苎麻雄性不育的早期表现和细胞学特征,采用常规石蜡切片,在显微镜下观察苎麻雄性不育系GS14-1及保持系GS13-X₁的雄蕊发育过程.发现保持系GS13-X₁的花药发育正常,形成正常的花粉粒;不育系GS14-1的雄性败育发生在较早阶段,多在雄花被形成后雌雄蕊原基分化期或花药形成初期发生败育,表现为雄蕊原基畸形或退化.但其败育的真正原因尚不清楚,有待进一步研究.     

化学药剂诱导矮败小麦的子房发育研究

在大田条件下,采用人工授粉,同时在隔离条件下,用化学药剂(成份:500 m g·kg- 1对氯苯氧乙酸+ 100 m g·kg- 1激动素+ 1.5% 二甲基亚砜处理矮败小麦的子房,并以水处理为对照。取材后做石蜡切片,观察子房的发育进程。结果表明:(1)人工授粉的子房发育到一定时期形成成熟的胚和胚乳。(2)化学药剂处理的子房,开始时膨大,胚囊内八核体积增大。随后,胚囊内的八核逐渐解体,子房壁逐渐变薄,有的最后仅剩一薄层子房壁;有的靠近珠心内侧有胚乳细胞出现,但未出现胚。(3)水处理的子房,胚囊内的八核逐渐解体,无胚和胚乳出现,最后整个子房萎蔫。     

利用回交群体对小麦雌性不育基因的SSR标记

对普通小麦新601、雌性不育材料XND126及其BC1群体的育性进行了观察.分析结果表明,此组合中雌性不育表现为1对隐性基因的遗传.结合集群分析(Bulked Segregant Anal-ysis,BSA)法在亲本间筛选了1 080对微卫星引物,并利用回交群体对小麦雌性不育基因进行了SSR分子标记,确定微卫星引物cfd36标记与雌性不育基因连锁,其遗传距离为13.0 cM.     

小麦83A败育和2721恢复力的细胞学观察

小麦不育系83A、41A小孢子母细胞的减数分裂和单核花粉期基本正常.小孢子能通过两次有丝分裂形成三核花粉粒.但在有丝分裂中观察到落后染色体、微核和大小不等的精核.小孢子败育主要发生在三核花粉期及其以后.败育类型属于圆败.其败育原因可能与遗传物的丢失、分配不均和细胞器的分化不良有关.恢复系2721、143和 F_1的花粉大而圆,细胞质充实饱满,花粉活力强,结实率高,故2721和143是较好的恢复系.     

小麦雄性不育系和保持系小孢子发育的电子显微镜观察

本工作对小麦雄性不育系及其保持系的小孢子和绒毡层,应用电子显微镜进行了研究,得到如下的结果: (1)不育系小孢子的败育,绝大多数发生在“大液泡期”,电子显微镜观察,显示各种细胞器解体或退化;少数不育系“小液泡期”的小孢子,也有发生细胞器的解体。 (2)在败育前的和正在败育的小孢子中,经常出现的一种核糖蛋白体状颗粒,它们的性质及其与不育性的关系尚未能肯定。 (3)在不育系的绒毡层和小孢子的发育过程中,液泡系即溶酶体系统的发育与保持系相比,有较显著的差别。液泡系的行为,可能可以作为小孢子败育的最早的形态上的标志。     

Advances in the understanding of inter-subspecific hybrid sterility and wide-compatibility in rice

Hybrid sterility is a major form of postzygotic reproductive isolation and frequently occurs in hybrids between divergent populations, such as the indica and japonica subspecies of Asian cultivated rice （Oryza sativa L.）. It has been a major barrier for utilization of the strong heterosis expressed in hybrids between indica and japonica. A large number of loci for rice inter-subspecific hybrid sterility have been identified by genetic analysis. Cytological studies revealed that male and female gamete abortions and reduced affinity between the uniting gametes all occurred in indica-japonica hybrids, suggesting the complexity of the causes for inter-subspecific hybrid sterility. Two genes conditioning embryo-sac and pollen sterility respectively in indica-japonica hybrids have been cloned recently, providing opportunities for molecular characterization of the indica-japonica hybrid sterility and wide-compatibility. Future studies should aim at cloning more genes for indica-japonica hybrid sterility, characterizing the underlying molecular mechanism, and utilization of the findings for the development of inter-subspecific hybrids to increase rice productivity.     

Identifying neutral allele Sb at pollen-sterility loci in cultivated rice with Oryza rufipogon origin

Pollen sterility is commonly found in the intra-specific hybrids of indica and japonica rice, which is one of the main constrains for the utilization of heterosis between indica and japonica. Six loci controlling the pollen sterility of F1 between indica and japonica have been identified from previous studies. Neutral alleles at each locus are potential to overcome the F1 pollen sterility associated with the locus. Therefore, exploitation and utilization of neutral alleles are of significant importance. The present research was based on fine mapping of the F1 pollen-sterility gene Sb and the abundant genetic diversity of Oryza rufipogon Griff. indigenous to Gaozhou, Guangdong Province （referred to as Gaozhou wild rice）. Crosses were made using Taichung65 （with the genotype of Sb^jSb^j and referred to as El） and its near-isogenic line of F1 pollen sterility gene Sb（with the genotype of Sb^iSb^i, E2） as female parents, and 12 different accessions of Gaozhou wild rice as male parents. F1 pollen fertility was examined to identify the materials having the neutral alleles at the F1 pollen-sterility locus. Segregation of 4 molecular markers tightly linked with the Sb locus was analyzed in the F2 populations derived from the FlS carrying the neutral gene. The pollen fertility related to the 3 genotypes of the molecular markers was also checked by statistical test to determine whether it was consistent with the hypothesis. The results showed that the pollen fertility of two F1s from one accession of Gaozhou wild rice （GZW099） with E1 and E2 was （89.2±21.07）% and （85.65±1.05）%, respectively. Both of them were fertile and showed no significant difference by t-test. Segregation of the 3 genotypes of the 4 molecular markers followed the expected Mendelian ratio （1：2：1） in the F2 populations. There was no significant difference for the averaged pollen fertility of the plants related to the 3 genotypes, suggesting that no interaction exists between the alleles at the Sb locus in GZW099 and Taichung65 or E2. Evidentially, GZW099 carried the neutral gene （named Sb″Sb″） at the Sb locus, which provides valuable theoretical basis and resources for further studying and overcoming the sterility of indica-japonica hybrids.     

Testes and chromosomes in interspecific hybrids betweenHelicoverpa armigera (Hübner) andHelicoverpa assulta (Guenée)

The interspecific hybridization betweenHelicoverpa armigera females andHelicoverpa assulta males yieldedF ₁ hybrids (RS), fertile males and sterile individuals with abnormal genitals. The reverse hybridization betweenH. assulta females andH. armigera males yielded F₁ hybrids (SR)-fertile males and fertile females. The morphology of testes and the karyotype of chromosomes of larvae in the hybrids were investigated. Among the 2d old fifth-instar SR larvae, individuals without testes were fertile females and those with testes were fertile males. The length and breadth of testes between SR and parental species were not significantly different (p>0.05). Among the 2d old fifth-instar RS larvae, the testes were observed in all the individuals, but it could be classified into two types. The length and the breadth of testes in Type 1 larvae were not significantly different from those of their parental species (p>0.05), while those in Type 2 were significantly less than those of their parental species (p<0.01). Mitotic metaphase I of brain cells showed the diploid chromosomes number of both reciprocal hybrids was 2n=62, as many as their parents. The haploid number of 31 was confirmed by counts from spermatocytes at meiotic metaphase from SR male larvae and Type 1 larvae of RS. Meiosis was not observed in spermatocytes of Type 2 larvae of RS. Considering the characteristics of adult hybrids of RS, it was concluded that Type 1 individuals in RS were fertile and those of Type 2 were sterile. The sterility of Type 2 individuals in RS is attributed to the abnormity in development of testes and the failing meiosis of spermatocytes. As a result, the normal spermatozoon could not been produced.     

陆地棉显性无腺体品系与常规品种间杂种优势利用研究Ⅰ．杂种一代产量相关性状通径分析

以７个显性无腺体陆地棉品系和４个常规品种为材料，按ＮＣⅡ设计，对２８个组合的Ｆ_１及亲本进行了通径分析。结果表明：杂种一代的产量构成与亲本明显不同，其产量构成因素中对皮棉产量贡献的大小依次是单株铃数＞铃重＞衣分；而亲本中为衣分＞铃重＞单株铃数。     

应用基因组原位杂交鉴定杂交后代中的簇毛麦染色体

用地高辛（Digoxigenin-11-dTup)标记的簇毛麦染色体组DNA为探针，以普通小麦“中国春”总DNA作封阻进行基因组荧光原位杂交，对小麦和簇毛麦杂交和回交后代进行检测。结果显示，在杂交后代的28条染色体中有7条簇毛麦染色体，在发生部分染色体加倍的回交代后鉴定出含7条簇毛麦染色体重的易位系。GISH的准确鉴定以及易位系的获得为向小麦导入簇志麦的有用基因提供了宝贵材料。     

小麦染色体2DS雌性育性位点遗传多态性分析

小麦雌性不育系XND126属于生态遗传型不育系.通过SSR分子标记分析,在2DS染色体上定位了一个雌性育性主效QTL位点.为了构建高密度遗传图谱并精细定位该主效位点,用2DS参考遗传图谱上的14对SSR标记,研究了59个育性正常的普通小麦品种与XND126的DNA多态性,筛选到不同生态型多态性较高的品种共12个,每个品种多态性标记达12~13个,这些品种可以用作杂交亲本,构建新的QTL精细定位群体.在品种组成的群体中,与主效基因位点最近的标记,表现出有较多的品种与雌性不育系具有差异.     

Genetic rescue of inviable hybrids between Drosophila melanogaster and its sibling species

Post-mating mechanisms are central to the establishment of reproductive isolation between different, but closely related, species. Post-mating isolation mechanisms include hybrid breakdown, hybrid sterility and hybrid lethality and may, in some cases, be reinforced by pre-mating mechanisms such as ethological differentiation. In the Drosophila melanogaster species sub-group post-mating reproductive isolation is ensured by both the inviability and the sterility of hybrids. For example when D. melanogaster females are crossed to D. simulans males the hybrid progeny are normally all female; the hybrid males die as third instar larvae. The viable hybrid females are totally sterile. Little is known of the genetic basis for either hybrid sterility or hybrid inviability, although Coyne and others have begun a genetic analysis of the sterility of hybrids within this species sub-group. We have discovered a single gene difference that rescues the otherwise inviable male hybrids from the cross between D. melanogaster females and males of its three closest relatives. The study of this locus may shed light on the genetic control of both speciation and development.     

A new type of triploid crucian crap?red crucian carp (♀)×allotetraploid (♂)

A new type of triploid hybrids (TC) was produced by crossing red crucian carp (♀) with allotetraploid hybrids (♂). This type of triploids with no barbel was spindle-shaped and gray in color. Compared with their parents, some data of the morphological traits in the triploid hybrids were intermediate to those of their parents, and some were beyond their parents with heterozygous traits. Under the same culture conditions, the growth rate of the new type triploids was faster than their maternal red crucian carp (RC). The gonadal development of triploids was obviously slower than that of diploids, and the germ cells in them were degenerated. Compared with another type of triploids produced by Japanese crucian carp (♀) with allotetraploid hybrids (♂), the new type triploids not only kept faster growth rate and sterility, but also had no barbel that was similar to the common carp. The absence of the barbel in the new type of triploids has the important significance in both the inheritance and fish breeding.     

Relationship between differ- ential gene expression pat- terns in functional leaves of maize (Zea mays L.) at milk filling stage and heterosis using cDNA-AFLP

The genetic mechanism of heterosis has been one of the most challenging subjects in life science since the 20th century. However, because of the complexity of its genetic basis and the limitations of research methods and means, there was no substantial progress in the research of heterosis from the beginning of the 20th century to the 1990s. The development in molecular biology and bio- technology, especially that in quantitative trait loci (QTL) mapping methods, has made it possible to resea…