Z6／陕7859胚培养再生植株的细胞遗传学研究与易位系选育

二体附加系Ｚ６携带抗大麦黄矮病毒病基因,为了将其抗性导入小麦,将Ｚ６与普通小麦陕７８５９杂交,杂种Ｆ１经幼胚培养诱导形成再生植株,对再生植株及后代进行抗性鉴定,农艺性状考察及对ＳＣ２部分抗病植株花粉母细胞减数分裂期染色体行为进行了观察。结果表明,（１）ＳＣ２不同单株间存在染色体数目,结构的变异。（２）同一再生植株后代的不同单株,染色体数目可能相同,但染色体组成及减数分裂期行为可心不同,致使后代抗性     

Chromosome and DNA damage and their repair in higher plants irradiated with short-wave ultraviolet light

In this review the authors present only their own results. They include the determination of the duration of the different stages of the cell cylce in UV-irradiated barley cells, the effect of different UV doses on the frequency of chromosome aberrations in barley, the increase in UV-induced chromosome aberration frequency induced in barley by caffeine and the effect of UV doses on the induction of pyrimidine dimers and sites sensitive to UV-endonuclease action (ESS) in barley cells and Nicotina tabacum protoplasts. In addition, the excision of pyrimidine dimers and ESS after irradiation with various doses of UV, unscheduled DNA synthesis in N. tabacum protoplasts and the correlation between the induction of pyrimidine dimers in DNA and the frequency of chromosome aberrations are reported. Data demonstrating that photoreactivation decrease the number of DNA lesions and chromosome aberrations induced by UV are also presented.     

Stable progeny production of the amphidiploid resynthesized Brassica napus cv. Hanakkori, a newly bred vegetable

Resynthesized Brassica napus cv. Hanakkori (AACC, 2n?=?38) was produced by cross-hybridization between B. rapa (AA, 2n?=?20) and B. oleracea (CC, 2n?=?18) as a new vegetative crop. Many studies have provided evidences for the instability and close relationship between A and C genome in the resynthesized B. napus cultivars. In fact, seed produced to obtain progeny in Hanakkori had unstable morphological characters and generated many off-type plants. In this study, we investigated the pollen fertility, chromosome number, structure, and behavior linked to various Hanakkori phenotypes to define factors of unstable phenotypic expression in the progeny. Hanakkori phenotypes were categorized into five types. The results of pollen fertility, chromosome number, and fluorescence in situ hybridization analysis for somatic mitosis cells indicated that the off-type plants had lower pollen fertility, aberrant chromosome number, and structures with small chromosome fragments. Observation of chromosomes at meiosis showed that the meiotic division in off-type plants led to appreciably higher abnormalities than in on-type plants. However, polyvalent chromosomes were observed frequently in both on- and off-type plants in diplotene stage of meiosis. We assume that the unstable morphological characters in resynthesized progeny were the result of abnormal division in meiosis. It results as important that the plants of normal phenotype, chromosome structure and minimized abnormal meiosis are selected to stabilize progeny.     

Evaluation of the effect of pollen irradiation on karyotype variability in cotton plants

The effect of pollen irradiation at dose rates of 10, 15, 20, and 25 Gy on variability in cotton plants Gossypium hirsutum L. was studied. The modified plants showed a reduced fertility, mainly caused by chromosomal rearragements and genomic mutations during meiosis. The genomic mutations involved primary and tertiary monosomics, monotelodisomics, and a haploid plant. The decrease in meiotic index and pollen fertility in the cotton aneuploids was related not only to aberrations in chromosome pairing but also to genetic features of the original plants. It was found that heterozygosity for interchromosomal exchanges found in M1 plants resulted in the formation of multivalent associations of chromosomes of various forms and types of segregation from translocation complexes. Another result was high variability in pollen fertility. An increase in irradiation dose rate caused an increase in the number of translocants with a high frequency of quadrivalents. The results suggest that the great diversity of forms observed in M1 after pollination with irradiated pollen is determined, first, by elimination of some chromosomes or their arms or the whole paternal genotype and second, by interchromosomal rearrangements. The high variability in pollen fertility of translocants hampers using this trait as a marker of heterozygosity for exchanges in cotton.     

A DNA-damage-induced cell cycle checkpoint in Arabidopsis

Although it is well established that plant seeds treated with high doses of gamma radiation arrest development as seedlings, the cause of this arrest is unknown. The uvh1 mutant of Arabidopsis is defective in a homolog of the human repair endonuclease XPF, and uvh1 mutants are sensitive to both the toxic effects of UV and the cytostatic effects of gamma radiation. Here we find that gamma irradiation of uvh1 plants specifically triggers a G(2)-phase cell cycle arrest. Mutants, termed suppressor of gamma (sog), that suppress this radiation-induced arrest and proceed through the cell cycle unimpeded were recovered in the uvh1 background; the resulting irradiated plants are genetically unstable. The sog mutations fall into two complementation groups. They are second-site suppressors of the uvh1 mutant's sensitivity to gamma radiation but do not affect the susceptibility of the plant to UV radiation. In addition to rendering the plants resistant to the growth inhibitory effects of gamma radiation, the sog1 mutation affects the proper development of the pollen tetrad, suggesting that SOG1 might also play a role in the regulation of cell cycle progression during meiosis.     

Evaluation of the Effect of Pollen Irradiation on Karyotype Variability in M1 Cotton Plants

The effect of pollen irradiation at dose rates of 10, 15, 20, and 25 Gy on variability in cotton plants Gossypium hirsutum L. was studied. The modified plants showed a reduced fertility, mainly caused by chromosomal rearrangements and genomic mutations during meiosis. The genomic mutations involved primary and tertiary monosomics, monotelodisomics, and a haploid plant. The decrease in meiotic index and pollen fertility in the cotton aneuploids was related not only to aberrations in chromosome pairing but also to genetic features of the original plants. It was found that heterozygosity for interchromosomal exchanges found in M₁ plants resulted in the formation of multivalent associations of chromosomes of various forms and types of segregation from translocation complexes. Another result was high variability in pollen fertility. An increase in irradiation dose rate caused an increase in the number of translocants with a high frequency of quadrivalents. The results suggest that the great diversity of forms observed in M₁ after pollination with irradiated pollen is determined, first, by elimination of some chromosomes or their arms or the whole paternal genotype and second, by interchromosomal rearrangements. The high variability in pollen fertility of translocants hampers using this trait as a marker of heterozygosity for exchanges in cotton.     

萍乡显性核不育水稻花粉败育的细胞形态学观察

利用光学显微镜技术对萍乡显性不育水稻（PXDGMSR）可育株和不育株花粉形成及发育过程,药壁组织的基本结构及其发育进行了研究,导致其不育株花粉败育的主要原因有：（1）绒毡层细胞解体延迟;（2）花粉母细胞减数分裂方式为“连续型”,但分裂期细胞液泡化严重,染色体粘连,纺缍体形成不规则,核中出现囊泡化现象,（3）花粉母细胞减数分裂方式为“同时型”,母细胞形成多核现象。     

Effects of Ultraviolet and X-Ray Radiation on in vitro Cultivated Cells of Haplopappus gracilis

A cell strain of Haplopappus gracills was used for investigations of the effects of UV (2537 A) and X-ray irradiation. Mitotic inhibition and killing after UV exposure were studied. A survival curve of UV treated and then plated cells is presented. The LD₅₀ seems to be about 2000 erg. mm^?2 under the experimental conditions used. All types of chromosome aberrations are induced by UV irradiation, but the frequency is relatively low at doses which do not completely inhibit cell division. A mutant strain of chromosome type is isolated after UV treatment and then plating. Mitotic inhibition and killing after X-ray treatment were studied. A survival curve is presented and the LD₅₀ under the culture conditions used seems to be about 2000 R. The frequency of chromosome aberrations induced by X-rays is highly increased by aeration during X-ray treatment which indicates that some degree of cell anoxia exists in a cell suspension. There arr indications that chromosome aherrations may not cause growth inhibition to such an extent as is usually believed.     

华北落叶松小孢子母细胞(PMC)减数分裂和花粉的发育

采用染色体压片法系统地观察了华北落叶松Larix principis-rupprechtii小孢子母细胞(PMC)减数分裂的细胞学特征和花粉发育过程。结果表明:华北落叶松PMC减数分裂始于当年秋季,以弥散双线期的特殊状态休眠越冬,次年春天又重新恢复其后续的减数分裂过程。主要特点是在同一花药中,减数分裂不同步,且各阶段分裂速度较快,3天内全部停留在四分体阶段;二价体构型主要为两臂共发生过两次以上交换的环形二价体,少数细胞中偶见一臂发生交换的棒状二价体;其平均构型为10.62II 1.38II;中期II核分裂相既有平行式样,又有互为垂直式样,形成左右对称型和四面体型四分体,兼具单、双子叶植物四分体主要类型特点。四分体持续一周后,细胞壁开始溶解,4个小孢子分离并游离在药室中,成为独立的单核花粉。其后细胞核开始有丝分裂,最后形成由2个原叶细胞、1个管细胞、1个柄细胞和1个体细胞共5个细胞组成的成熟花粉。此外,还观察到成熟花粉当中有13.6%是由4个细胞组成的。     

Short periods of high temperature during meiosis prevent normal meiotic progression and reduce grain number in hexaploid wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Key message

Exposure of wheat to high temperatures during male meiosis prevents normal meiotic progression and reduces grain number. We define a temperature-sensitive period and link heat tolerance to chromosome 5D.

Abstract

This study assesses the effects of heat on meiotic progression and grain number in hexaploid wheat (Triticum aestivum L. var. Chinese Spring), defines a heat-sensitive stage and evaluates the role of chromosome 5D in heat tolerance. Plants were exposed to high temperatures (30 or 35 °C) in a controlled environment room for 20-h periods during meiosis and the premeiotic interphase just prior to meiosis. Examination of pollen mother cells (PMCs) from immature anthers immediately before and after heat treatment enabled precise identification of the developmental phases being exposed to heat. A temperature-sensitive period was defined, lasting from premeiotic interphase to late leptotene, during which heat can prevent PMCs from progressing through meiosis. PMCs exposed to 35 °C were less likely to progress than those exposed to 30 °C. Grain number per spike was reduced at 30 °C, and reduced even further at 35 °C. Chinese Spring nullisomic 5D-tetrasomic 5B (N5DT5B) plants, which lack chromosome 5D, were more susceptible to heat during premeiosis–leptotene than Chinese Spring plants with the normal (euploid) chromosome complement. The proportion of plants with PMCs progressing through meiosis after heat treatment was lower for N5DT5B plants than for euploids, but the difference was not significant. However, following exposure to 30 °C, in euploid plants grain number was reduced (though not significantly), whereas in N5DT5B plants the reduction was highly significant. After exposure to 35 °C, the reduction in grain number was highly significant for both genotypes. Implications of these findings for the breeding of thermotolerant wheat are discussed.

     

鱼腥草花粉母细胞减数分裂特征及其育性研究

为深入了解鱼腥草花粉母细胞的减数分裂特征与花粉育性的关系,该研究采用卡宝品红染色法对2个鱼腥草居群花粉母细胞的减数分裂过程进行观察,并采用氯化三苯基四氮唑(TTC)染色法、I2-KI染色法、B-K培养基培养法及荧光显微镜观察法来检测鱼腥草花粉的活力及萌发率。结果发现:(1)鱼腥草减数分裂的进程与花序大小、花药颜色、花药长度均有密切的关系。(2)2个居群的鱼腥草中花粉母细胞减数分裂过程正常占88.2%,有11.8%的花粉母细胞减数分裂异常。(3)减数分裂异常表现在减数分裂过程中出现微核、落后染色体、染色体桥、不均等分离、多分体等现象,并发现在二分体阶段及单核花粉发育过程中存在细胞融合。(4)2个居群的鱼腥草花粉活力均不超过1.5%,花粉几乎不萌发。研究认为,鱼腥草花粉育性低的主要原因是单核花粉的发育过程异常,而非鱼腥草花粉母细胞减数分裂异常所致。     

Estimation of efficiency of seed irradiation by thermal neutrons for inducing chromosomal aberration in M2 of cotton Gossipium hirsutum L

Cytogenetic analysis of M2 plants after irradiation of cotton by thermal neutrons was performed in 56 families. In 40 plants of 27 M2 families, different abnormalities of chromosome pairing were found. These abnormalities were caused by primary monosomy, chromosomal interchange, and desynapsis. The presence of chromosome aberrations in some cases decreased meiotic index and pollen fertility. Comparison of the results of cytogenetics analysis, performed in M1 and M2 after irradiation, showed a nearly two-fold decrease in the number of plants with chromosomal aberrations in M2, as well as narrowing of the spectrum of these aberrations. The latter result is explained by the fact that some mutations are impossible to detect in subsequent generations because of complete or partial sterility of aberrant M1 plants. It was established that the most efficient radiation doses for inducing chromosomal aberrations in the present study were 15 and 25 Gy, since they affected survival and fertility of altered plant to a lesser extent.     

The Influence of Sucrose and Abscisic Acid on the Determination of Grain Number in Wheat

Using detached ears of wheat cultured in nutrient solution theeffect of sucrose and ABA supply on grain number was examined.In ears detached prior to ear emergence, to correspond withthe time of pollen mother cell meiosis, higher levels of sucroseuptake were associated with higher grain number per ear. ABAindirectly caused a reduction in grain number by decreasinguptake of sucrose through decreasing stomatal conductance andtranspiration. There was possibly also a direct effect of ABAon grain number. At higher levels of ABA the negative effecton grain number was decreased by increasing the sucrose concentration.In ears detached one to three days after anthesis grain numberwas also influenced by the amount of sucrose taken up. althoughgrain number was not as sensitive to the sucrose supply at thistime as it was at meiosis. The influence of ABA following anthesiswas limited to an indirect effect on grain number through reductionsin sucrose uptake. Key words: Wheat, Sucrose, ABA, Grain number     

远缘杂交油菜核不育系的创建及其细胞学和形态学研究

在甘蓝型油菜与诸葛菜以及芥菜型油菜与诸葛菜属间杂交后代中分别发现1个和3个不育材料,经杂交和多代近交育成了相应的甘蓝型油菜不育系。通过对核不育系体细胞鉴定表明,所有新发现的不育系染色体数为38,均已恢复到甘蓝型油菜。这些不育系绝大部分花粉母细胞（PMC）在中期Ⅰ、后期Ⅰ和后期Ⅱ 3个时期染色体行为表现正常,但不同时期的PMC均会出现一定比例的异常现象,主要表现为染色体落后或染色体桥等。这些不育系属于单核败育型,不育株与可育株的花器形态差异明显,不育系还存在不同程度的死蕾等特点。通过对花器生长过程的研究,发现不育株雌蕊生长随雄蕊败育进程逐渐加快,而可育株雌蕊生长则存在两个生长缓慢阶段。此外,文章还讨论了这些不育系的应用前景。     

芝麻核雄性不育系ms86-1微粉发生的细胞学观察

芝麻(Sesamum indicum)核雄性不育系ms86-1姊妹交后代表现为可育、部分不育(即微粉)及完全不育(简称不育)3种类型。不同育性类型的花药及花粉粒形态差异明显。Alexander染色实验显示微粉植株花粉粒外壁为蓝绿色, 内部为不均一洋红色, 与可育株及不育株花粉粒的染色特征均不相同。为探明芝麻微粉发生机理, 在电子显微镜下比较观察了可育、微粉、不育类型的小孢子发育过程。结果表明, 可育株小孢子母细胞减数分裂时期代谢旺盛, 胞质中出现大量脂质小球; 四分体时期绒毡层细胞开始降解, 单核小孢子时期开始出现乌氏体, 成熟花粉时期花粉囊腔内及花粉粒周围分布着大量乌氏体, 花粉粒外壁有11–13个棱状凸起, 表面存在大量基粒棒, 形成紧密的覆盖层。不育株小孢子发育异常显现于减数分裂时期, 此时胞质中无脂质小球出现, 细胞壁开始积累胼胝质; 四分体时期绒毡层细胞未见降解; 单核小孢子时期无乌氏体出现; 成熟花粉时期花粉囊腔中未发现正常的乌氏体, 存在大量空瘪的败育小孢子, 外壁积累胼胝质, 缺乏基粒棒。微粉株小孢子在减数分裂时期可见胞质内有大量脂质小球, 四分体时期部分绒毡层发生变形, 单核小孢子时期有部分绒毡层开始降解; 绒毡层细胞降解滞后为少量发育进程迟缓的小孢子提供了营养物质, 部分小孢子发育为正常花粉粒; 这些花粉粒比较饱满, 表面有少量颗粒状突起, 但未能形成覆盖层, 花粉囊腔中及小孢子周围存在少量的乌氏体。小孢子形成的育性类型与绒毡层降解是否正常有关。     

The Development and a Cytogenetic Study of Monosomics of Gossypium Hirsutum L.

Monosomics of cotton (Gossypium hirsutum L.) were obtained by irradiation of pollen by -rays and by irradiation of seeds by thermal neutrons. Many monosomics were derived directly from irradiation, but a number of monosomics were also recovered in the progeny of plants with translocations and of desynaptic plants. Only 28 primary monosomics showed normal pairing at metaphase-1 of meiosis. The others formec rare trivalents or additional univalents. Partial desynapsis was detected in some monosomics. The pollen fertility levels of monosomics are presented. New morphological characters were detected among the monosome plants of cotton.     

中国鹅掌楸小孢子发生的细胞化学研究

多糖、脂类和蛋白质的消长变化与花粉发育过程中营养供应存在着密切的关系。雄蕊特别是花药壁内的多糖在减数分裂过程中逐渐消耗殆尽。初期的小孢子母细胞内脂滴的含量丰富,无淀粉粒,也无颗粒状的蛋白质。进行减数分裂的小孢子母细胞内、中层及绒毡层细胞积累了大量的蛋白质与脂类;减数分裂完成后,绒毡层和四分体小孢子开始逐渐积累淀粉与脂类,但蛋白质的含量较少,至小孢子时期,小孢子壁及绒毡层细胞的径切向壁和内切向壁沉积了大量的脂类物质,而且小孢子核周围分布大量淀粉粒,未观察到蛋白质颗粒。     

Distinct chromatin environment associated with phosphorylated H3S10 histone during pollen mitosis I in orchids

Pollen developmental pathway in plants involving synchronized transferal of cellular divisions from meiosis (microsporogenesis) to mitosis (pollen mitosis I/II) eventually offers a unique “meiosis-mitosis shift” at pollen mitosis I. Since the cell type (haploid microspore) and fate of pollen mitosis I differ from typical mitosis (in meristem cells), it is immensely important to analyze the chromosomal distribution of phosphorylated H3S10 histone during atypical pollen mitosis I to comprehend the role of histone phosphorylation in pollen development. We investigated the chromosomal phosphorylation of H3S10 histone during pollen mitosis I in orchids using immunostaining technique. The chromosomal distribution of H3S10ph during pollen mitosis I revealed differential pattern than that of typical mitosis in plants, however, eventually following the similar trends of mitosis in animals where H3S10 phosphorylation begins in the pericentromeric regions first, later extending to the whole chromosomes, and finally declining at anaphase/early cytokinesis (differentiation of vegetative and generative cells). The study suggests that the chromosomal distribution of H3S10ph during cell division is not universal and can be altered between different cell types encoded for diverse cellular processes. During pollen development, phosphorylation of histone might play a critical role in chromosome condensation events throughout pollen mitosis I in plants.