Isoenzyme Polymorphism in Flowering Plants

Esterases, leucine aminopeptidases, catalases and acid phosphatases from pollen of Oenothera organensis were studied electrophoretically. A study was made using several different extraction media to see the effect it had on esterase migration and stainability. It was found that different extraction media resulted in significant changes in migration rates and stainabilities of the esterase isozymes. Anodal esterases and leucine aminopeptidases from 13 inbred lines of maize were studied and are reported. Preliminary genetic studies of two of the esterase isozymes from maize pollen are reported. A survey of anodal esterases and leucine aminopeptidases from the pollen of 11 genera of diverse angiosperms is presented.     

Isoenzyme Polymorphism in Flowering Plants

A total of 21 esterase, 3 acid phosphatase and 2 leucinc aminopeptidase isoenzymes, in addition to peroxidases and catalases, were demonstrated in onion seedlings by starch-gel electrophoresis. In seedlings two weeks old, the root tip and the differentiated zone show very little enzymatic activity, whereas the secondary roots, hypo-cotyl and cotyledon are enzymatically very active. These differences are correlated with the intensity of cell division. Some esterase isoenzymes are apparently restricted to root, others to shoot tissues. At pH 8.1, anodically moving peroxidases are totally absent from shoot tissues. A developmental study of esterase isoenzyme patterns indicated that no great differences exist between primary root tips from roots 6–18 mm long and seeds germinated for three days, whereas a sudden decrease in enzymatic activity occurs in root tips after seven days' germination when the roots are about 25 mm long. This coincides with the decrease in mitotic Frequency. Actinomycin D and gamma irradiation decreased mitotic frequency almost to zero but did not significantly affect the esterase isoenzyme pattern in root tips. This shows that the activity of these isoenzymes, at least, is not necessarily dependent on cell division but may well be a prerequisite for it.     

Isoenzyme Polymorphism in Flowering Plants III Gel Electrophoretic Methods and Applications

Gel electrophoretic methods and equipment which were devised or modified for rapid and economic application to angiosperm tissues are described. Staining schedules are outlined that proved effective on a wide variety of tissues for elucidation of isoenzymes with the following activities; eslerase, peroxidase, catalase, leucine amino peptidase, phosphatase, amylase, and glutamic-oxalacetic-transaminase. Illustrative applications are discussed.     

Isoenzyme Polymorphism in Flowering Plants. IV. The Peroxidase Isoenzymes of Maize (Zea mays)

Twenty-four peroxidase isoenzymes were identified by starch gel electrophoresis of 250 varieties of maize. Twelve of these bands corresponded in electrophoretic mobility to bands observed in commercial horseradish peroxidase. Maize tissues varied greatly in isoenzyme pattern, many tissues having a characteristic and distinguishing complement. Ontogenetic variations were observed for the leaf blade, leaf sheath, and internodes during maturation, and were related to the rates of tissue enlargement. Genetic studies of two isoenzymes, C10 and C20, indicated that they were conditioned by alleles of a single locus, here designated Px₁.     

被子植物生殖细胞与精细胞的分离方法

开花植物精细胞的发育经历一个独特的后减数分裂过程,在此过程中每个花粉母细胞减数分裂的产物——小孢子经不对称有丝分裂产生1个大的营养细胞和1个小的生殖细胞,随后生殖细胞经过正常的有丝分裂产生2个精细胞。近几年,随着高通量组学技术的不断完善,利用组学技术比较分析生殖细胞和精细胞的分子特征、揭示决定精细胞命运与功能以及受精识别的重要分子已成为植物生殖生物学备受关注的课题。开展此项研究的关键是建立能获得大量高纯度的生殖细胞与精细胞分离纯化技术。该文综述了被子植物生殖细胞和精细胞分离方法的主要研究进展,分析了关键方法的特点和要点以及不同方法之间的差异和共性,以期为相关领域的研究人员提供借鉴。     

显花植物自体和异体花粉识别的分子机理研究(英文)

显花植物的受精涉及许多识别过程;其中第一个是雌性生殖组织心皮对花粉的识别。自交不亲和性（Ｓｅｌｆ－ｉｎｃｏｍｐａｔｉｂｉｌｉｔｙ,ＳＩ）是一种广泛分布于显花植物的种内生殖障碍。在多数自交不亲和的植物中,ＳＩ的遗传控制比较简单,受控于一个由复等位基因构成的单一位点,称为Ｓ位点。在以茄科、玄参科和蔷薇科为代表的配子体自交不亲和植物中,Ｓ位点编码一类核酸酶,即Ｓ核酸酶（Ｆｉｇ．１）,控制ＳＩ在花柱中的表达,但是与花粉自交不亲和性的表达无关。后者可能由与Ｓ核酸酶不同的基因控制,这种基因常被称为花粉Ｓ基因。它是目前了解显花植物花粉识别生化和分子机理的关键。近来;通过对影响花粉ＳＩ表达突变体的分子遗传分析提出了一个花粉Ｓ基因产物如何与Ｓ核酸酶相互作用完成自体和异体花粉识别过程的模型（Ｆｉｇ．２）。另外,描述了两个在金鱼草中克隆花粉Ｓ基因的方法,即Ｓ位点选择性的转座子标记和图位克隆。     

Isolation of Sperms from the Pollen Tubes of Flowering Plants during Fertilization

Sperm cells have been isolated from pollen tubes growing in style segments of the dicotlyledon Rhododendron macgregoriae and the monocotyledon Gladiolus gandavensis by the in vivo/in vitro method at various stages of fertilization. Pollen tubes emerged from the cut end of the style into agar medium, and more than 95% contained sperm cells. Sperm cells were released from the pollen tubes by osmotic shock or by placing styles in wall-degrading enzymes: 0.5% macerozyme and 1% cellulase. The isolated sperms were ellipsoidal protoplasts of diameter about 2 × 3 micrometers in Gladiolus and about 3 × 4 micrometers in Rhododendron. After isolation, a proportion of the sperm cells occurred in pairs linked at one end by finger-like connections. The pairs of isolated sperms were dimorphic in terms of surface area and volume. By cutting the styles at various positions and times after pollination, the potential exists to detect changes in sperm gene expression associated with fertilization.     

Electrorotation of Isolated Generative and Vegetative Cells, and of Intact Pollen Grains of Lilium longiflorum

The dielectric structure of mature pollen of the angiosperm Lilium longiflorum was studied by means of single-cell electrorotation. The use of a microstructured four-electrode chamber allowed the measurements to be performed over a wide range of medium conductivity from 3 to 500 mS m⁻¹. The rotation spectra of hydrated pollen grains exhibited at least three well-resolved peaks in the kHz-MHz frequency range, which obviously arise due to the multilayered structure of pollen grains. The three-shell model can explain the complex rotational behavior of pollen grains in terms of conductivities, permittivities and thicknesses of the following compartments: the exine and intine of the pollen grain wall as well as the membrane and cytoplasm of the vegetative cell. However, the number of unknown parameters (more than 8) was too large to allow unambiguous values to be assigned to any of them. Therefore, to facilitate the evaluation of the pollen grain parameters, additional rotational measurements were made on isolated vegetative and generative cells. The rotation spectra of these cells could be fitted very accurately on the basis of the single-shell model by assuming a dispersion of the cytoplasm. The data on the membrane and cytoplasmic properties of isolated vegetative cells were then used for modeling the rotation spectra of pollen grains. This greatly facilitated the fitting of the theoretical model to the experimental data and allowed the dielectric properties of the major structural units to be determined. The dielectric characterization of pollen is of enormous interest for plant biotechnology, where pollen and isolated germ cells are successfully used for production of transgenic crop and drug plants of economic importance by means of electromanipulation techniques. Received: 9 June 1997/Revised: 4 August 1997     

Influence of Pollen Transport Dynamics on Sire Profiles and Multiple Paternity in Flowering Plants

In many flowering plants individual fruits contain a mixture of half- and full- siblings, reflecting pollination by several fathers. To better understand the mechanisms generating multiple paternity within fruits we present a theoretical framework linking pollen carryover with patterns of pollinator movement. This ‘sire profile’ model predicts that species with more extensive pollen carryover will have a greater number of mates. It also predicts that flowers on large displays, which are often probed consecutively during a single pollinator visitation sequence, will have a lower effective number of mates. We compared these predictions with observed values for bumble bee-pollinated Mimulus ringens, which has restricted carryover, and hummingbird-pollinated Ipomopsis aggregata, which has extensive carryover. The model correctly predicted that the effective number of mates is much higher in the species with more extensive carryover. This work extends our knowledge of plant mating systems by highlighting mechanisms influencing the genetic composition of sibships.     

海南岛叶下珠属4种植物花粉形态学及活性酶比值分析

本研究用醋酸酐分解法处理叶下珠属4种植物花粉,在光学显微镜和扫描电镜下作形态学详尽观测和序列分析4种花粉所含8种活性酶组分含量总比值变化.结果表明4种植物花粉的外部形态、内部结构都有明显的差异,萌发孔、内外壁的形态和表面纹饰特征变化异常;花粉的活性酶比值变化,以叶下珠(214.87)＞海南叶下珠(203.46)＞崖县叶下珠(196.06)＞沙地叶下珠(194.22).这与种(源)质变异、产地生境不一,相关密切.     

Fluorescence Microscopy in the Study of Pollen Grains and Pollen Tubes

Fresh pollen gains were either crushed directly in a 0.01% solution of acridine orange (0.1 M phosphate-citrate buffer, pH 5.2-5.4) or they were germinated previously in 5-25% sucrose solution (glass-distilled water of pH 5.0-6.0 with 100 ppm H₃BO₃) inside moist incubating chambers at 24-30° C. Observations and records were made by using ultraviolet or blue-violet light with suitably coupled exciter and barrier filters. When the pollen grains, tube walls or cytoplasm interfered with observation of a particular cell content, the same was either pressed or dissected out of the gain or the tube. The vegetative, generative or sperm cells as well as other protoplasmic contents, such as plastid-like bodies, lipid granules and mitochondria could be differentiated.