水稻雄性不育与花药中类脂褐素的积累

细胞质雄性不育水稻不育系珍汕９７Ａ和其保持系珍汕９７Ｂ,处于不育期的光（温）敏核不育水稻Ｗ６１５４ｓ和培矮６４ｓ的花药中类脂褐素（ＬＦＬＰ）含量随花粉发育或败育而增高．不育花药中ＬＦＬＰ的形成速率比可育花药快,三核期的珍汕９７Ａ和不育期Ｗ６１５４ｓ的花药,其ＬＦＬＰ比相应具育性花药高２４％．用抗氧化剂ＧＳＨ、ＢＨＴ和Ｎ２处理离体的单核期花药,发现ＧＳＨ可降低珍汕９７Ａ和不育期的Ｗ６１５４ｓ的ＬＦＬＰ含量．结果认为,水稻雄性不育与膜脂过氧化作用的荧光产物类脂褐素的积累有关．     

太谷核不育小麦可育花药内游离脯氨酸的来源、利用及与不育花药败育的关系

太谷核不育小麦营养体内的游离脯氨酸能迅速地运入并积累于花药中,花药有将谷氨酸转化成脯氨酸的能力。脯氨酸向花药内以主动运输为主,能被DNP所抑制,与旗叶的功能密切相关。在发育阶段Ⅰ(小孢子释放前后),脯氨酸已不能由营养体运入不育花药,运输的障碍在花丝或花药中,不育花药缺乏游离脯氨酸可能是主要原因。发育阶段Ⅰ的可育花药内,脯氨酸是合成蛋白质或其他大分子物质的原料。因而,脯氨酸的缺乏可能是加速不育花药小孢子败育和小孢子释放后急剧解体的重要原因。     

THE EFFECT OF 3-AMINO-1,2,4-TRIAZOLE ON THE ULTRASTRUCTURE OF PLASTIDS OF TRITICUM VULGARE SEEDLINGS

The application of sublethal doses of 3-amino-1,2,4-triazole (AT) to germinating, light-grown wheat grains causes chlorosis of the resulting leaves. An ultrastructural examination of the leaf tissue reveals that the plastids lack normal grana-fret membrane systems and chloroplast ribosomes. A few disorganized membranes are always present in these chloroplasts. However, AT-treated, dark-grown seedlings contain proplastids with non-crystalline prolamellar bodies and ribosomes. When these etiolated, treated plants are exposed to 600 ft-c light for various periods of time, the proplastids fail to develop into normal, grana-containing chloroplasts.     

白菜细胞核雄性不育花药的细胞化学观察

对一种由一对隐性基因控制的白菜细胞核雄性不育和可育株的花药进行了细胞学和组织化学研究。种子播种后,有1/4植株为不育株,其余的为可育株。通过对不育株和可育株花药发育的细胞学观察,确认不育花粉的败育发生在小孢子发育时期。用组织化学的方法研究了可育株和不育株花药发育过程中的多糖和脂类的分布动态,发现在减数分裂前,可育花药和不育花药的药隔细胞中都储藏了大量的淀粉粒。二者的差异仅是不育花药的绒毡层细胞液泡化明显。在减数分裂后的小孢子发育时期,可育花药的绒毡层细胞具有将药隔细胞中的淀粉粒多糖吸收并转化成脂类的功能,小孢子及以后的二胞花粉中也积累了大量的脂类储藏物质在不育花药中,虽然减数分裂后药隔细胞中的淀粉粒也都消失,但绒毡层细胞中的脂类物质相比很少,同时绒毡层细胞显示了明显的多糖反应,表明不育花药的绒毡层细胞将糖类转化为脂类的功能受阻。在小孢子的表面有些脂类物质,但在细胞质中却没有脂类积累。这一结果暗示在该种白菜细胞核雄性不育株中,由于花药绒毡层细胞转换多糖为脂类的功能失常,导致了小孢子的败育。     

Effects of exogenous application of polyamines on wheat anther cultures

Androgenesis of wheat genotypes was evaluated by pretreating anthers or embryo-like structures (ELS) with polyamines. Anthers of the genotype DH were pretreated with different concentrations of putrescine, spermidine, and spermine for 1, 3, and 6 h, and those of drought-tolerant International Center for Agricultural Research in the Dry Areas (ICARDA) wheat accessions were treated for 1 and 3 h. ELS of two genotypes were also treated for 30 and 60 min with the same polyamines and evaluated for green plant regeneration. The pretreatment of anthers with polyamines enhanced the development of ELS in all genotypes. The formation of ELS varied significantly with genotype. Pretreated anthers showed that four treatments improved significantly green plant regeneration with the genotype ICR 17. However, two treatments (1 mM putrescine or spermine for 1 h) significantly improved green plant regeneration per 100 ELS of only two ICARDA genotypes. ELS treated with polyamines for 30 min were greener and formed more adventitious roots. The chloroplasts of these greener ELS examined with a transmission electron microscope had agranal to grana thylakoids, while those of the control had plastids with mostly starch globules. Although exogenous application of polyamines to anthers improved the production of ELS and green plants, the effects of putrescine, spermidine, and spermine was dependent on genotype and the duration of pretreatment of anthers with the polyamines.     

SOME PROPERTIES OF PROTOPLASMIC GELS : II. CONTRACTION OF CHLOROPLASTS IN CURRENTS OF WATER ENTERING THE CELL AND EXPANSION IN OUTGOING CURRENTS

The chloroplasts of Nitella may contract under natural conditions as well as under the influence of certain reagents. When a sufficient amount of water enters any part of the cell they contract in that region and they expand when the direction of the current is reversed. The current may be produced by placing water at one end of the cell and applying at the other end a solution which withdraws water from the cell. The contraction may be due to the washing out of substances from the chloroplast by the ingoing current. The outgoing current bearing dissolved materials from the sap may restore these substances and cause the chloroplasts to resume their normal shape. When blood or sodium dodecylsulfate is present in the ingoing current the contraction of the chloroplast usually fails to occur.     

Differentiation of haploid and dihaploid rape plants at the cytological and morphological levels

Some cytological and morphological features of haploid and dihaploid winter rapó plants obtained via the anther cultivation approach have been studied. It was shown that in haploid plants the number of chloroplasts in stomatal guard cells, the size of the stomatal guard cells themselves were much smaller, and the number of stomata per square unit was greater than in doubled haploids and diploids. Haploids were also characterized by smaller sizes of petals and anthers and, in general, a smaller flower as compared to dihapliods and diploids.     

INCORPORATION OF H3-THYMIDINE INTO CHLOROPLAST DNA OF MARINE ALGAE

The chloroplasts of three genera of marine algae, Dictyota, Padina, and Bryopsis, were labeled with tritiated-thymidine for various time periods during culture in "Erd-Schreiber's" solution. Autoradiographs were prepared from both smeared and sectioned material. They revealed that almost all of the radioactivity was in the cytoplasm and associated with the chloroplasts, as detected in the overlying silver halide crystals. Deoxyribonuclease, ribonuclease, and hot trichloracetic acid treatments indicated that the loss of radioactivity corresponded to the removal of DNA and not RNA. Quantitative studies of silver grain distribution suggested that the radioactivity of the labeled DNA originated from the edge of the pyrenoids on either side in the longitudinal direction of Bryopsis chloroplasts. Nuclei did not incorporate H³-thymidine even though cells were dividing rapidly in the three genera examined. It is postulated that the enzyme, thymidine kinase, is absent as a coding sequence of nuclear DNA in algae, but is present in chloroplast DNA. When the chloroplasts of Dictyota and Padina in various stages of division were scored for labeling, there appeared to be a DNA synthesis period, analogous to S period in cell division. This chloroplast-labeling period occurred just previous to fission. Many of the criteria seem to have been satisfied to establish the self-reproducing and semi-autonomous nature of chloroplasts, especially when combined with the chemical, genetic, and morphological evidence.     

AN ULTRASTRUCTURAL STUDY OF CHLOROPLAST STRUCTURE AND DEDIFFERENTIATION IN TISSUE CULTURES OF STREPTANTHUS TORTUOSUS (CRUCIFERAE)

Cells of Streptanthus tortuosus callus tissue contain chloroplasts when cultured in a liquid medium in the light. Similar cells grown in the dark contain proplastids that fail to develop prolamellar bodies but do contain a complex of loosely-associated membranes. When green, light-grown cultures are cut into small pieces and subcultured to a fresh culture medium, they become bleached even though maintained under the same illumination. The fine structure of the chloroplasts and the chlorophyll content of the cells indicate a dedifferentiation of the chloroplasts to a proplastid state during the early culture period. The changes in the ultrastructure of the plastids are paralleled by a dedifferentiation of the vacuolate cells to a less differentiated, meristematic state. Subsequent growth in the light results in a re-formation of chloroplasts and an increase in the chlorophyll content of the cells. The period of chloroplast redevelopment is associated with the re-formation of large central vacuoles in the cultured cells. Invaginations of the inner membrane of the plastid envelope occur at all stages of plastid development and are not lost during the period of grana degeneration. The proplastids formed from the dedifferentiation of the chloroplasts contain a large number of these invaginations and the redevelopment of grana is associated with a change in the electron density of the invaginating membranes. The degradation of the chlorophyll-containing membranes of the grana occurs during a period of rapid cytoplasmic synthesis induced by the fresh supply of nutrients in the culture medium. These results suggest that the high levels of nutrients may act directly on the chloroplasts and cause their dedifferentiation or that the rapid cell growth induced by the nutrients may cause a degradation of the membrane proteins in the grana of the chloroplasts and an incorporation of the released amino acids into non-plastid components of the cytoplasm.     

A STUDY OF THE RELIABILITY OF SYNCHRONY IN THE DEVELOPMENT OF POLLEN MOTHER CELLS OF LILIUM LONGIFLORUM AT THE FIRST MEIOTIC PROPHASE

Lilium longiflorum anthers have been used by a number of investigators as a source of supposedly synchronous cells for studying genetic, chromosomal and molecular events of meiotic prophase I. Because of questions raised by the literature as to the reliability of such synchrony, new baseline data were obtained for L. longiflorum ‘Croft’ in preparation for experiments requiring homogeneity or synchrony. Homogeneity was found to be reliable at the same level of locules of the same anther and of anthers from the same bud up to the onset of diplotene. Synchrony deteriorates rapidly from diplotene on. Less than half the anthers examined had PMC's at the same stage from apex to base. Hence experiments requiring complete homogeneity within anthers would call for rigorous monitoring of each anther included in the sample. Synchrony between buds of the same length was insufficient to allow bud length to be used as a reliable index of meiotic stage.