Die Primärwurzel von Zea mays L.

Zusammenfassung An Gewächshauskulturen kann gezeigt werden, daß die Primärwurzel von Zea mays L. während der ganzen Lebensperiode der Pflanze perenniert. Da auch bei Phoenix dactylifera L. eine solche Tendenz zu erkennen ist, ist es wahrscheinlich, daß weitere Monocotylen diese Art der Bewurzelung zeigen. Es ließe sich daraus ein Maiswurzeltyp der heterogenen Radication bei den Monocotylen ableiten, bei dem primäres und sproßbürtiges Wurzelsystem dauernd nebeneinander bestehen.

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The primary root of Zea mays L.

Summary Until now it has been presumed that the primary root of Zea mays L. dies very soon after the formation of the seedling. On the basis of this presumption maize root-system development has been used as an example for monocotyledons (z.B. Troll, 1937; Rauh, 1950).After passing the seedling stage, monocotyledons are said to have shoot-born roots only. There are a few hints in the literature of exceptions to this principle known in the case of some palms (Falkenberg, 1876; Fitting, 1954; Kausch, unpublished). In this paper it is shown that the primary root of maize does not die off soon, but remains living during the entire vegetation period. Investigations were made within the greenhouse, where in the stage of flowering of the plants the primary root reached downwards into the soil as far as 1.60 m (see also Fig. 2). There are also some observations in the open field showing that here too the primary root remains living until the plant dies in autumn.Nevertheless Zea mays has sekundäre Homorhizie and heterogene Radication (Troll, 1949). However, there is surely a large group within the monocotyledons which is capable of keeping the primary root system along with shoot-born roots. Of this group it may be said that it is of the Mais-Wurzel-Typ.

     

Evolution of female sexuality in the maize ear (Zea mays L. subsp.mays—Gramineae)

The discovery of staminodes within the female inflorescences, or “ears,” of some Mexican maize races, and of feminized male inflorescences in annual Mexican teosinte, provides additional support for the theory that the ears of maize evolved from the male primary lateral branch tassels of teosinte by sexual transmutation, and that teosinte is the wild ancestor of maize.     

Enzyme des Stärkeumsatzes in den Wurzelhaubenzellen von Zea mays L.

Summary In connection with the problem of the well-known stability of statolith starch, some enzymes of starch metabolism have been investigated qualitatively in the root cap cells of Zea mays L. No activity of granule-bound UDPG- and ADPG-transglucosylase (EC 2.4.1.21) could be found. In the soluble enzyme fraction of the root cap cells, on the other hand, activities of phosphorylase (EC 2.4.1.1), sucrose synthetase (EC 2.4.1.13), UDPG-pyrophosphorylase (EC 2.7.7.9), -Amylase (EC 3.2.11), Maltase (EC 3.2.1.20), and D-enzyme (EC 2.4.1.25) were clearly shown to be present. However, no measurable activities of ADPG-pyrophosphorylase, sucrose-6-phosphate-synthetase (EC 2.4.1.14) and UDPG-dehydrogenase (EC 1.1.1.22) could be found. It is concluded that the stability of statolith starch in the root cap cells is not caused by the lack of enzymes of starch metabolism, but perhaps by a dynamic equilibrium between the degradation and the synthesis of starch. The later could proceed by the activity of phosphorylase working in the direction of starch synthesis because of removal of the inorganic phosphate by phosphorylating mitochondria accumulating in the neighbourhood of the statolith amyloplasts.     

Beiträge zur Entwicklungsgeschichte des sporogenen Gewebes der Gramineen und Cyperaceen. I.Zea mays

Zusammenfassung Auf Grund einer besonderen Zellteilngsfolge, die als mechanisch bedingt zu verstehen ist, ordnen sich die sporogenen Zellen beiZea mays so an, daß sie im Loculusquerschnitt wie die Sektoren eines Kreises um den Mittelpunkt herum liegen. Bei den folgenden Zellteilungen steht die Längsachse der Spindel den räumlichen Gegebenheiten entsprechend immer parallel, nie senkrecht, zur Antherenwand. Es erfolgen also keine Teilungen mehr in radialer Richtung, was im Zusammenwirken mit der Einstellung des Zellwachstums in antikliner Richtung bewirkt, daß die sporogenen Zellen im Zentrum des Antherenfaches auseinanderweichen und schließlich einen Hohlraum bilden.Die Pollenmutterzellen kleiden in einer Lage den Pollensack aus. Ihre Form ist ± stumpf-keilförmig, langgestreckt und die Längen ihrer drei Achsen verhalten sich ungefähr wie 321. Die längste Achse der Pollenmutterzellen und damit auch die Längsachse der Spindel der I. meiotischen Teilung steht immer parallel zur Antherenwand.Die Spindelanordnung der II. meiotischen Teilung erfolgt ebenfalls entsprechend den Raumverhältnissen. Die Spindeln stehen immer parallel zueinander, zur ersten Scheidewand und zur Antherenwand. Diese Art und Weise der Teilung führt dazu, daß die vier Zellen einer Tetrade sich in einer Ebene befinden und dem Tapetum anliegen. Auch nach der Isolierung der Mikrosporen wird diese Lage beibehalten.Die Auswirkung mechanischer Gesetzmäßigkeiten bei der Entwicklung des sporogenen Gewebes vonZea mays ist so stark, daß möglicherweise noch vorhandene andere Faktoren nur eine untergeordnete Rolle spielen.An dieser Stelle möchte ich Frau R.Wunderlich meinen besonderen Dank für mannigfache Beratung aussprechen.     

Starch Mobilization in Ultradried Seed of Maize （Zea mays L.） During Germination

The effects of ultradry storage on the starch mobilization in maize (Zea mays L.) seed after aging were investigated. The results indicated that there were no significant differences in the content of ATP, starch, and soluble sugar, as well as the activity of amylase, between ultradried seeds and seeds stored at -20℃ during germination. These results were consistent with the higher level of vigor of the ultradried seed. Sieve tube introduction of a fluorescence dye (carboxyl fluoresceindiacetate) and laser confocal microscopy were used to study the development of plasmodesmata in the ultradried seeds. The results indicated that plasmodesmata developed well in ultradried seeds. Fluorescence analysis also showed that the fluorescence intensity in the radicle of ultradried seeds was stronger than that in seeds with a higher moisture content. This suggests that ultradry treatment has no adverse effects on the seeds. After seed imbibition, cell orgaelles could be resumed. It is concluded that ultradry seed storage is beneficial for maintaining seed vigor and that starchy mobilization proceeds regularly during germination.     

Heterozygosity of Knob-Associated Tandem Repeats and Knob Instability in Mitotic Chromosomes of Zea （Zea mays L. and Z. diploperennis Iltis Doebley）

Knobs are blocks of heterochromatin present on chromosomes of maize （Zea mays L.） and its relatives that have effects on the frequency of genetic recombination, as well as on chromosome behavior. Knob heterozygosity and instability in six maize inbred lines and one Z. diploperennis Iltis Doebley line were investigated using the fluorescence in situ hybridization （FISH） technique with knob-associated tandem repeats （180 bp and 350 bp （TR- 1）） as probes. Signals of seven heterozygous knobs containing 180- bp repeats and of one heterozygous knob containing TR- 1 were captured in chromosomes of all materials tested according to the results of FISH, which demonstrates that the 180-bp repeat is the main contributor to knob heterozygosity compared with the TR- 1 element. In addition, one target cell with two TR- 1 signals on one homolog of chromosome 2L, which was different from the normal cells in the maize inbred line GB57, was observed, suggesting knob duplication and an instability phenomenon in the maize genome.     

玉米(Zea mays L.)叶脉发育的研究

玉米的叶脉在单子叶植物中有一定的代表性,叶脉由四级组成,粗细不同的一、二、三级叶脉均从叶基向叶尖方向延伸,属叶片的纵向叶脉,四级脉横向与一、二、三级叶脉连接,是横向的叶脉,各级叶脉有各自的形成方式,由于它们有规律的分布,从而构成了叶片的输导网络,各级叶脉的发生和发育与叫片的生长有直接的关系。     

Protein Changes in Response to Pyrene Stress in Maize （Zea mays L.） Leaves

Phytoremedlation is a relatively new approach to remove polycyclic aromatic hydrocarbons （PAHs） from the environment. When plants are grown under pyrene treatment, they respond by synthesizing a set of protective proteins. To learn more about protein changes in response to pyrene treatment, we extracted total proteins from the leaves of maize （Zea mays L.） 1 week after pyrene treatment. The proteins extracted were separated with twodimensional gel electrophoresis. In total, approximately 54 protein spots were found by comparing gels from treated and control groups. According to the Isoelectric point, molecular weight, and abundance of these protein spots, 20 pyrene-lnduced proteins were found to have changed abundance. Of these, 15 protein spots were Increased and five protein spots were newly appeared in pyrene-treated plant leaves. Six model upregulated protein spots of different molecular weights were excised from the gels and subjected to trypsin digestion followed by peptide separation using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Peptlde masses were used to search the matrix-science database for protein Identification. Two of the proteins were Identified on the basis of the homology of their peptide profiles with existing protein sequences as pyruvate orthophosphate diklnase and the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunlt. These proteins are Involved in the regulation of carbohydrate and energy metabolism. The present study gives new Insights into the pyrene stress response In maize leaves and demonstrates the power of the proteomlc approach in phytoremedlation of PAHs.     

麦茬处理方式对夏玉米（Zea mays L.）根际生物活性的影响

通过两年3点的大田试验,研究了不同麦茬处理方式(平茬、立茬、除茬)对夏玉米(Zea mays L.)根际生物活性的影响.结果表明:不同麦茬处理的夏玉米根际微生物数量、土壤蛋白酶和脲酶活性均呈先升后降的变化趋势,且在吐丝期达到最大值,但在不同生育时期,不同处理间有所差异,趋势为平茬>立茬>除茬,且苗期差异较大,后期逐渐减小.麦茬处理方式对夏玉米田土壤碳通量的影响也表现出同样趋势.     

Down-Regulation of ZmEXPB6 (Zea mays β-Expansin 6) Protein Is Correlated with Salt-mediated Growth Reduction in the Leaves of Z. mays L.

The salt-sensitive crop Zea mays L. shows a rapid leaf growth reduction upon NaCl stress. There is increasing evidence that salinity impairs the ability of the cell walls to expand, ultimately inhibiting growth. Wall-loosening is a prerequisite for cell wall expansion, a process that is under the control of cell wall-located expansin proteins. In this study the abundance of those proteins was analyzed against salt stress using gel-based two-dimensional proteomics and two-dimensional Western blotting. Results show that ZmEXPB6 (Z. mays β-expansin 6) protein is lacking in growth-inhibited leaves of salt-stressed maize. Of note, the exogenous application of heterologously expressed and metal-chelate-affinity chromatography-purified ZmEXPB6 on growth-reduced leaves that lack native ZmEXPB6 under NaCl stress partially restored leaf growth. In vitro assays on frozen-thawed leaf sections revealed that recombinant ZmEXPB6 acts on the capacity of the walls to extend. Our results identify expansins as a factor that partially restores leaf growth of maize in saline environments.     

玉米（Zea mays L.）cdc2和Prh1基因的染色体原位杂交物理定位

首次报道了玉米两个低拷贝基因ｃｄｃ２和ｐｒｈ１生物素标记的染色体原位杂交结果。供试探针为这两个基因的ｃＤＮＡ克隆ｃｄｃ２ＺｍＡ和ＺｍＰＰ１,其长度分别为１．３ｋｂ和１．７ｋｂ。结果表明,ｃｄｃ２ＺｍＡ的信号分布在第４、８和９染色体长臂,与着丝粒的百分距离分别为５７．８７±２．６８、２８．４２±１．４５和８８．１６±３．２８,检出率为１０．０７％．３．１３％和８．３３％。ｐｒｈ１ＺｍＰＰ１的信号分布在第４、６和８染色体长臂,与着丝粒的百分距离分别为５３．６２±１．１７．６０．７７±２．９０和１７．１０±１．６１,检出率为１２．０７％．５．１７％和６．４７％。对非放射性原位杂交技术以及基因ｃｄｃ２和ｐｒｈ１的物理位置与功能间的关系作了讨论。     

Physiological Responses of Zea mays Seedlings to Interactions Between Cadmium and Salinity

The effects of 0, 2.5, 5.0, and 10.0 pmol/L Cd^2＋（Cd（NO3）2.4H2O） and 0, 10, 25, 50, and 100 mmol/L NaCl on growth, photosynthesis and the content of some ions in maize （Zea mays L.） were investigated in the present study. With Increasing concentrations of Cd^2＋ or NaCI alone in Hoagland nutrient solution, the chlorophylls and starch content decreased. Combination treatment with salinity and cadmium increased the negative effects observed following the two stresses alone. Plants exhibiting growth retardation in response to one mild stress factor （25-50 mmol/L NaCl） became more tolerant to the other stress factor （Cd）. The exposure of plants to cadmium caused a partial reversal of the effects of salinity. Root and shoot growth, ion accumulation and levels of photosynthetic pigments were improved at moderate concentrations of the two stress factors Imposed jointly.     

Two high-density AFLP® linkage maps of Zea mays L.: analysis of distribution of AFLP markers

This study demonstrates the relative ease of generating high-density linkage maps using the AFLP® technology. Two high-density AFLP linkage maps of Zea mays L. were generated based on: (1) a B73 × Mo17 recombinant inbred population and (2) a D32 × D145 immortalized F₂ population. Although AFLP technology is in essence a mono-allelic marker system, markers can be scored quantitatively and used to deduce zygosity. AFLP markers were generated using the enzyme combinations EcoRI/MseI and PstI/MseI. A total of 1539 and 1355 AFLP markers have been mapped in the two populations, respectively. Among the mapped PstI/MseIAFLP markers we have included fragments bounded by a methylated PstI site (^mAFLP markers). Mapping these ^mAFLP markers shows that the presence of C-methylation segregates in perfect accordance with the primary target sequence, leading to Mendelian inheritance. Simultaneous mapping of PstI/MseIAFLP and PstI/MseI ^mAFLP markers allowed us to identify a number of epi-alleles, showing allelic variation in the CpNpG methylation only. However, their frequency in maize is low. Map comparison shows that, despite some rearrangements, most of the AFLP markers that are common in both populations, map at similar positions. This would indicate that AFLP markers are predominantly single-locus markers. Changes in map order occur mainly in marker-dense regions. These marker-dense regions, representing clusters of mainly EcoRI/MseI AFLP and PstI/MseI ^mAFLP markers, co- localize well with the putative centromeric regions of the maize chromosomes. In contrast, PstI/MseImarkers are more uniformly distributed over the genome.     

Cytoplasmic free calcium in Riccia fluitans L. and Zea mays L.: Interaction of Ca2+ and pH?

In cells of Zea mays (root hairs, coleoptiles) and Riccia fluitans (rhizoids, thalli) intracellular Ca²⁺ and pH have been measured with double-barrelled microelectrodes. Free Ca²⁺ activities of 109–187 nM (Riccia rhizoids), 94–160 nM (Riccia thalli), 145–231 nM (Zea root hairs), 84–143 nM (Zea coleoptiles) were found, and therefore identified as cytoplasmic. In a few cases (Riccia rhizoids), free Ca²⁺ was in the lower millimolar range (2.3±0.8 mM). A change in external Ca²⁺ from 0.1 to 10 mM caused an initial and short transient increase in cytoplasmic free Ca²⁺ which finally levelled off at about 0.2 pCa unit below the control, whereas in the presence of cyanide the Ca²⁺ activity returned to the control level. It is suggested that this behaviour is indicative of active cellular Ca²⁺ regulation, and since it is energy-dependent, may involve a Ca²⁺-ATPase. Acidification of the cytoplasmic pH and alkalinization of the vacuolar pH lead to a simultaneous increase in cytoplasmic free Ca²⁺, while alkalinization of pH_c decreased the Ca²⁺ activity. Since this is true for such remote organisms as Riccia and Zea, it may be concluded that regulation of cytoplasmic pH and free Ca²⁺ are interrelated. It is further concluded that double-barrelled microelectrodes are useful tools for investigations of intracellular ion activities in plant cells.Symbols and abbreviations _m, _m membrane potential difference, changes thereof - PVC polyvinylchloride     

Plastid targeting of E. coli β-glucuronidase and ADP-glucose pyrophosphorylase in maize (Zea mays L.) cells

Summary Dicot and monocot chloroplast targeting peptides (CTPs) were evaluated for their effect on targeting, processing, and expression of two reporter proteins in maize cells. When tested transiently in maize leaf protoplasts, the maize ribulose bisphosphate carboxylase small subunit CTP required the inclusion of the amino terminus of mature small subunit protein to target -glucuronidase (GUS) to the plastid. To remove this amino terminal extension from GUS after import and processing, a repeat of the native processing site was inserted between the native mature protein and the reporter protein. This repeat processing site was used with less efficiency than the native site. Parallel constructs using the Arabidopsis thaliana small subunit and maize granule-bound starch synthase CTPs also localized GUS, but varied in repeat site use and GUS expression levels. Data from the CTP fusions with GUS were generally confirmed with fusions to an allosteric variant of E. coli ADP-glucose pyrophosphorylase. Plastid targeting of this enzyme was required for starch enhancement of transgenic BMS cells.Abbreviations BMS maize Black Mexican Sweet suspension culture cells - CTP chloroplast targeting peptide - glgC16 an allosteric variant of E. coli ADP-glucose pyrophosphorylase - GUS -glucuronidase - LUX luciferase - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - SSU small subunit of ribulose bisphosphate carboxylase     

Attempted “egg transformation” in Zea mays L., using irradiated pollen

Summary Experiments were conducted to determine if egg transformation could be achieved in Zea mays L. as described by Pandey in Nicotiana L. Multiple recessive and multiple dominant marker stocks were employed, as well as a tester and a donor line for the En transposable element. Recipient tester females were pollinated with dominant donor pollen, which was applied in several treatment combinations. The pollination treatments included: 1) pollen irradiated at 20, 30, 40, 80, and 100 Krad; 2) pollen irradiated with the same doses, mixed with non-irradiated recipient pollen; 3) pollen irradiated at 80 Krad, followed by self pollination delayed 18 h; 4) non-irradiated donor pollen mixed with non-irradiated recipient pollen. Zero seed were produced from 100 pollinations with irradiated pollen. There were 258 pollinations made with irradiated donor plus self pollen mixtures, producing over 21,300 seed. Of these seed, 3 were unexpected. One was clearly from pollen contamination, one was clearly derived from a pre-meiotic mutation, and the third occurred as a mutant sector in the seed's endosperm. There were 56 pollinations with non-irradiated pollen mixtures, producing over 5,000 seed. Among these seed, there were 7 unexpected seed. Three of these were clear-cut cases of heterofertilization. Four progeny were dominant for all seed and seedling markers except one endosperm marker. These cases appear to represent spontaneous recessive endosperm mutations. More than 59,000 potential transformation events were screened producing only 6 apparent mutations. It is concluded that if egg transformation occurs in Zea mays, it is a very rare event, and is not likely to be useful in corn improvement.Approved by the Director of the New York State Agricultural Experiment Station for publication as Journal Paper No. 3556     

Location and Analysis of Introgressed Segments in the Parthenogenetic Progenies of Zea mays×Z.diploperennis by GISH

玉米×二倍体多年生类玉米孤雌后代渗入片段的GISH定位分析     

我国南方糯玉米(Zea mays Sinensis)的过氧化物酶同工酶分析

本试验用垂直平板聚丙烯酰胺凝胶电泳法,比较分析了我国南方糯玉米的过氧化物酶同工酶。共测定了70个品种(系),其中53个糯玉米,17个其他玉米类型、玉米野生亲缘种。结果表明,我国南方糯玉米的大多数(86.8%)品种,其过氧化物酶同工酶带特征与起源于中国的Coix 属相似,具有第5带。而起源于美洲大陆的马齿型玉米则具有第4带。这就进一步证明,中国糯玉米(Zea mays Sinensis)可能原产于我国南方。中国不仅是玉米的次生起源中心,而且也可能是初生起源中心之一。     

Unterschiedliche CO2-Abhängigkeit des Gasaustausches beider Blattseiten von Zea mays

Summary CO₂ exchange and transpiration of the two leaf surfaces of Zea mays were measured at various external CO₂ concentrations between 50 and 10000 ppm (V/V). The CO₂ exchange of the upper surface followed an optimum curve with a maximum near 300 ppm, whereas the CO₂ exchange of the lower epidermis approximated a saturation curve from 100 to 3000 ppm. The transpiration data of both leaf surfaces at three CO₂ concentrations indicated that these results were due to stomatal interference with the saturation curve of photosynthesis. The results show, again that the guard cells of the two leaf surfaces can react differently. Data obtained with viscous flow porometers or with diffusion porometers employing an unidirectional diffusion of a gas, through an amphistomatic leaf should therefore be interpreted with great caution.

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Teil einer Dissertation der Naturwissenschaftlichen Fakultät der Justus Liebig-Universität Gießen.