平流层辐射SP_3谷子雄性细胞发育的研究

对平流层辐射处理ＳＰ３谷子和对照ＣＫ３谷子雄性细胞发育的研究表明,雄性细胞正常发育过程从孢原细胞开始,经初生造孢细胞、次生造孢细胞、小孢子母细胞、二分体、四分体和单核小孢子中央期、单核小孢子液泡期（单核靠边期）、单核小孢子成熟期直到二细胞花粉、三细胞成熟花粉结束。其中四分体形成属连续型。雄性细胞异常发育有几种情况：小孢子母细胞强烈液泡化,细胞质收缩解体,不能进入减数分裂;小孢子母细胞液泡化,呈能进     

水松花粉中的淀粉粒和胼胝质

水松花粉母细胞在１２月下旬至第二年元月上旬进行减数分裂，散粉时的成熟花粉为２－细胞结构。前期Ⅰ，淀粉粒主要分布在花粉母细胞内的周围。中期Ⅰ至末期Ⅱ，淀粉粒逐渐向中期Ⅰ，Ⅱ所形成的赤道区处聚集。花粉发育期中，淀粉粒聚集在核的周围，但这些淀粉粒在散粉前全部消失。胼胝质首先出现在花粉母细胞内壁和质膜之间，然后在减Ⅰ，Ⅱ赤道区处形成一环形和两个半圆形的胼胝质。营养细胞和生殖细胞周围及其之间具有明显的胼胝质荧光。     

Expression of an Antisense BcMF3 Affects Microsporogenesis and Pollen Tube Growth in Arabidopsis

In an effort to provide some information relevant to the molecular mechanism of genic male sterility in plants, BcMF3 gene that encodes a pectin methylesterase was isolated from the fertile B line of Chinese cabbage-pak-choi （Brassica rapa ssp. chinensis, syn. B. campestris ssp. chinensis）. In the present paper, a 455-bp antisense cDNA fragment of BcMF3 was introduced to binary vector pB1121, and then was mobilized into Agrobacterium tumefaciens strain LBA4404. The A. tumefaciens harboring the BcMF3 antisense fragment was transformed to Arabidopsis thaliana by floral dip. Scanning electronic microscopy examination demonstrated that 47.8% of BcMF3 antisense pollen grains exhibited abnormal shape, which might lead to decreased germination of pollens, suggesting that the product of BcMF3 gene plays an important role during microsporogenesis. The evidence on burst of 45.7% of BcMF3 antisense pollen tubes in vitro and a majority of BcMF3 antisense pollens restricted within the stigmatic tissue revealed that BcMF3 is involved in aiding the growth of pollen tubes. The results suggest that BcMF3 acts at both stages of microsporogensis and pollen tube growth.     

月见草小孢子发生和雄配子体发育的研究

文章以月见草(Oenothera biennis L.)为研究对象,运用石蜡切片技术对其小孢子发生及雄配子发育进行研究。结果表明,月见草成熟花药有4个小孢子囊,花药壁发育为基本型。花药壁由5￣6层细胞构成,药室内壁宿存且于发育后期发生带状纤维加厚成为纤维层。绒毡层属腺质绒毡层。花粉母细胞减数分裂为连续型。成熟花粉2-细胞型为主,兼有少量3-细胞型。通过扫描电镜观察发现,成熟花粉粒呈三角形,花粉表面具3个萌发孔突起,花粉表面有褶皱纹饰。     

马铃薯(延薯4号)小孢子发生的细胞学观察

采用常规石蜡切片法,在光学显微镜下观察了马铃薯延薯4号品种的小孢子发生和各时期的形态特征.结果表明:马铃薯延薯4号小孢子发育经历了造孢细胞、小孢子母细胞、四分体等时期.四分体属四面体型,缄毡层属分泌型.延薯4号小孢子表现高度不育,败育发生在四分体时期开始,其主要特征是四分体胼胝质不能适时降解,致使四分体持续时间较长,细胞内核收缩降解,形成形状不规则、空瘪的小孢子.     

Influence of cytoplasmic-nuclear male sterility systems on microsporogenesis in pearl millet (Pennisetum glaucum (L.) R. Br.)

Influence of a range of cytoplasms on microsporogenesis and anther development in pearl millet was studied using six isonuclear A-lines having five cytoplasms (A₁, A₂, A₃, A₄ and A_v) and the nuclear genome of 81B. 81B was used as a male-fertile control. Microsporogenesis and anther development were normal in 81B. However, pollen mother cell (PMC)/microspore/pollen degeneration in the six A-lines occurred at different stages of anther development. Each cytoplasm had its unique influence on microsporogenesis and anther development as evidenced by different developmental paths followed by them leading to pollen abortion. The cause of pollen abortion differed from line to line, from floret to floret within a spikelet, from anther to anther within a floret, and in some cases even from locule to locule within an anther. Events that led to male sterility included anomalies in tapetum and callose behaviour, persistence of tapetum, endothecium thickness, and other unknown causes. The present study also indicated that anther/pollen development was more irregular in Pb 406A₃. In 81A₄ and 81A₁ > 95% of anther locules followed a definite developmental path to pollen abortion. In the other A-lines many developmental paths were observed within the line and pollen degeneration occurred at various stages. This could be one of the reasons for greater instability of male sterility in the A₂ and A₃ systems and greater stability of male sterility in the A₁ and A₄ systems. This revised version was published online in July 2006 with corrections to the Cover Date.     

Microsporogenesis and flower development in Eucalyptus urophylla × E. tereticornis

We compared microsporogenesis and flower development in Eucalyptus urophylla × E. tereticornis. In this study, although microsporogenesis and cytokinesis occurred simultaneously during meiosis of pollen mother cells, we observed a strong asynchronism in different anthers from a flower bud. The developmental period of microsporogenesis in anthers originated from the long thrum before the short thrum. Flower development was also asynchronous at different locations on a branch. The flower buds grew on the lower side of the branch and showed greater increases in diameter. In addition, we observed a relationship between microsporogenesis development and flower bud diameter growth. Generally, when the pachytene stage was first observed in a small single flower bud growing on top of a flowering branch, the remaining microsporogenesis stages (from diplotene to tetrad) in the whole branch occurred over the next 5–9 days. Thus, the start of microsporogenesis in E. urophylla × E. tereticornis could be determined, which may be applicable to future breeding studies.     

Chromosome number and microsporogenesis in a pentaploid accession of Brachiaria brizantha (Gramineae)

Chromosome number, microsporogenesis and mode of reproduction are described for an accession of Brachiaria brizantha, a grass of African origin. Cytological analysis revealed that the accession BRA005886 is pentaploid (2n = 5x = 45), with a base number of x = 9. Multivalent chromosome associations, from tri‐ to pentavalents, were recorded in diakinesis, and the further meiotic behaviour was highly irregular as well. Most abnormalities were related to irregular chromosome segregation commonly found in polyploids. Micronuclei were observed following telophases I and II. Some micronuclei near the cell wall were released as microcytes, whereas others remained in the tetrad. Other meiotic abnormalities, such as cell fusion and the absence of cytokinesis causing the formation of dyads and triads were also recorded. Binucleate microspores and 2n microspores resulting from nucleus restitution were observed among the normal ones. Limitations of this accession for use in hybridization programmes are discussed.     

大叶杨小孢子发生的组织化学观察*

大叶杨早期雄花以小孢子母细胞阶段越冬。大量淀粉粒贮存于花药表皮和药室内壁,并在减数分裂过程中向花药内部移动,逐渐消耗殆尽。与此同时,绒毡层细胞和小孢子母细胞逐渐积累多糖。绒毡层细胞始终含丰富的 DNA、RNA、蛋白质。RNA和蛋白质在小孢子发生过程中表现一致性的分布和含量变化。 小孢子母细胞在减数分裂前期Ⅰ细线期开始沉积胼胝质壁。胼胝质为颗粒状沉积,逐渐连结成片,于中期Ⅰ完全包裹小孢子母细胞。以后胼胝质壁加厚,于中期Ⅱ及后期Ⅱ达到最厚。四分体形成后,由四分体中央向各向辐射形成胼胝质侧隔壁。四分体多排列为四面体形,偶尔可见左右对称形、十字交互形排列。后期四分体周缘胼胝质壁溶解消失,小孢子释放。侧壁最后被溶解。