The promotion of ear emergence by gibberellic acid in Ethrel-induced male sterile wheat

Ethrel at a concentration of 2000 ppm active ingredient (a.L), applied to the spring wheat cv. Sirius before meiosis was initiated in the oldest florets of the ears, induced almost complete male sterility but prevented full ear emergence. Concentrations of 100, 200 and 300 ppm a.i. GA₃, applied 2 or 5 days after the Ethrel, were equally effective in promoting full emergence of sterilized ears, without affecting female fertility or markedly affecting flowering time.     

Electron-Microscope Observation on the Pollen Development of Male Sterility Wheat Induced by Ethrel

The pollen development of male sterility wheat induced by Ethrel was studied in comparison with that of normal wheat by transmission and scanning electron-microscope. The results obtained are summarized as follows: 1. The primary morphological changes of abortive wheat pollen after treatment with Ethrel took place in the vacuole stage. The materials of cytoplasm were rarefied. All kinds of the cell organelles and vacuoles became degenerated and disorganized. Inside a small number of cell nuclei, chromatin granules coagulated irregularly. The number and the activity of the Ubisch bodices became reduced evidently. 2. In the mature stage, the differences between the treated wheat and normal wheat became even more striking. The normal pollens were spherical in sharp, and full of starch granules. The treated pollen were monstrous. There was a large empty vacuole in every abortive pollen cell, in which the starch granules were smaller and fewer than these in the normal ones. The nuclei and cytoplasm in some of the abortive pollens were degenerated, leaving only the cell walls. 3. Under scanning electron microscope, it was discovered that the normal wheat pollen were spherical or oval. The germinated pores jutted. The round-openings of the pores could be clearly seen. The abortive pollen induced by Ethrel looked like some shrunken balls, and became deformed and were blocked up. 4. On discussion of the mechanism of the Ethrel-induced male sterility in wheat, the authors suggest that special attention should be paid to the changes of the Ubisch bodies and the vacuoles.     

Changes in the levels of free IAA and cytokinins in potato tubers during dormancy and sprouting

Changes in the levels of free indol-3-ylacetic acid (IAA) and free cytokinins were determined in the course of dormancy and sprouting period in potato tubers(Solanum tuberosum L., cv. Nevskii) stored at 4 °C. The same analyses were performed in potato tubers after Ethrel application, which prolongs dormancy. No significant changes were found in free IAA level during dormancy followed by a rapid decrease during sprouting. After Ethrel application a significant lower IAA level was found 3 weeks after application, but further on no changes in free IAA level between treated and non-treated tubers were detected. Cytokinin level was relatively low and constant till sprouting and increases then by about 55 %, mainly due to an increase in the level of zeatin riboside and isopentenyladenosine. Ethrel application decreased cytokinin level during dormancy slightly, but postpones the increase coupled with sprouting by about 1 month. Thus, IAA does not seem to have a significant effect on tuber dormancy, while cytokinins are probably necessary for sprouting initiation.     

Stimulation of ethylene evolution and abscission in cotton by 2-chloroethanephosphonic Acid

Ethrel, a mixture of 2-chloroethanephosphonic acid and its ethyl ester, hastens abscission of leaves, debladed petioles, and flower buds of cotton plants (Gossypium hirsutum, L.). Both young and old leaves abscissed while still green. Application of Ethrel stimulated evolution of ethylene, and this response preceded abscission. Air concentrations of ethylene around enclosed, treated-plants were adequate to produce abscission in plants. Non-treated plants defoliated when enclosed with plants sprayed with Ethrel. The stimulation of abscission of explant petioles by Ethrel was reversed by naphthalene acetic acid. The stimulation of abscission by Ethrel was concluded to be mediated by ethylene.     

Induction of embryogenic pollen grains in situ and subsequent in vitro pollen embryogenesis in Nicotiana tabacum by treatments of the pollen donor plants with feminizing agents

Tobacco plants ( Nicotiana tabacum L., var. Badischer Burley) were treated with chemicals (sprays and soil drenches) known to affect sex expression in other species. Their effect was tested on sex balance, pollen sterility, embryogenic pollen grain (P-grain) formation in situ, and on pollen plant formation in anther and pollen cultures after anther preculture. Napthalene acetic acid (NAA) increased the length of pistils and stamens and shifted sex balance towards femaleness when the plants were raised in long or short days at 24 or 15°C. In parallel, pollen sterility, P-grain frequency in situ and pollen plant production from anther and pollen cultures were increased by NAA. Alar 85 redueed the length of pistils and stamens and shifted sex balance towards femaleness when the plants were raised in long days at 24°C, but shifted it towards maleness in short days and/or at 15°C. In parallel, pollen sterility, P-grain frequency in situ, and pollen plant production in vitro were increased when plants in long days at 24°C were treated with Alar 85, but decreased when plants in short days and/or at 15°C were treated. Ethrel, Cycocel, and GA₃ applied in a similar manner, were ineffective. Water sprays and nitrogen starvation shifted sex balance towards femaleness in long days at 15°C and increased pollen sterility, P-grain frequency in situ and pollen plant production in vitro. At 24°C, water sprays and nitrogen starvation had no effect.     

雄性不育在作物杂种优势中的应用途径分析

雄性不育是植物雄性细胞或生殖器官丧失生理机能的现象,该现象的利用大大提高了杂交种生产的效率。植物雄性不育包含细胞质雄性不育、不受环境影响的核雄性不育、光温敏型雄性不育及化学诱导的雄性不育。这些不育类型也已经被以三系或二系的方式应用于很多作物的杂交种生产中。综述了雄性不育各个途径的研究进展及其在作物杂种优势中的应用。     

Putative role of ethylene in Datura metel microspore embryogenesis

The role of ethylene in microspore embryogenesis was analyzed by studying the effect of cobalt ions, silver ions, methionine and Ethrel on the androgenic response of in vitro cultured anthers of Datura metel L. Cobalt and silver ions, provided in the form of cobalt chloride and silver nitrate, respectively, decreased the average number of embryos/plantlets developed per anther, at all the concentrations tested. In contrast, methionine (10⁻⁵–10⁻³ M ) and Ethrel (10⁻⁶ and 10⁻⁵ M ) stimulated embryo formation. The optimal enhancement was recorded at 10⁻⁵ M of both methionine and Ethrel.     

Cambial activity in 'normal' spruce Picea abies Karst (L.) and snake spruce Picea abies (L.) Karst f. virgata (Jacq.) Rehd in response to ethylene

The concentration of ethylene accumulating in the outer portion of sapwood in stems was measured in normal spruce and snake spruce from March to July in 1997. During growth, the endogenous levels of ethylene were higher in stem sapwood in the common spruce than in the snake spruce. Dormant cuttings of both varieties were treated with various concentrations of ethylene gas or Ethrel and maintained for up to 5 weeks under environmental conditions favourable for growth. After harvest, cambial activity, measured as the number of tracheids formed, was measured both at, above and below the application point of ethylene gas or Ethrel. Both treatments stimulated cambial activity at the point of application with the effect being more pronounced in the snake spruce cuttings. The role of ethylene in the regulation of cambial growth rate in normal and snake spruce cuttings is evaluated.     

黄瓜茎端ABA/GA_4比值与花芽性别分化的关系(英文)

在同一环境条件下,单雌性株茎端ABA含量显著高于雌雄同株的,而GA_4水平却正好相反。 较高的ABA/GA_4比值有利于黄瓜雌性分化,反之则有利于雄性分化。促进黄瓜雄性分化的生长物质GA_3和AgNO_3会引起黄瓜茎端ABA/GA_4比值的下降,而促进其雌性分化的生长物质乙烯利(Ethrel)则会引起ABA/GA_4比值的上升。     

The role of ethylene during flooding of Phaseolus vulgaris

Wilting symptoms in Phaseolus vulgaris L. cv. bruine Noord-Hollandse were observed after a few hours of flooding. They were well correlated with an accumulation of ethylene. The ethylene level in the leaves started to increase after 2 h of flooding and reached a 3–4 fold rise after 4–6 h. From then on throughout the next two days it gradually returned to control values. On the day when plants were flooded, a positive correlation was found between the ethylene concentration and the degree of wilting. During this day the time course of abscisic acid (ABA) level, diffusion resistance and water potential was measured. The effect of ethylene on stomatal aperture was investigated by spraying Ethrel on the leaves. In control plants, Ethrel treatment had no influence on the diffusion resistance. Spraying plants with ABA resulted in a significant, dose-dependent increase in diffusion resistance. When Ethrel was added to the ABA-containing solutions only 62% of this increase was observed. Ethrel (pre-) treatment of plants that were to be flooded had a similar effect; the increase in diffusion resistance was only 70% of what was observed in untreated flooded plants. It is concluded that ethylene may interfere with the regulation of stomatal aperture by abscisic acid.     

Rooting of Chrysanthemum Stem Cuttings as Affected by (2-chloroethyl) Phosphonic Acid and Indolebutyric Acid

Stem cuttings of Chrysanthemum morifolium Ram. were treatedwith aqueous solutions of (2-chloroethyl)phosphonic acid (Ethrel)and indolebutyric acid (IBA). Ethrel (1 mg per 1) as a dip oras two foliar sprays, promoted root length and branching inMrs. Roy and Clipper which are difficult-to-root cultivars,but had no effect on Improved Mefo, an easy-to-root cultivar.IBA increased root number in both Clipper and Improved Mefo.The results suggest that IBA and Ethrel act at different stagesof the rooting process, with IBA promoting initiation and Ethrelstimulating elongation and branching. Increases in root numberwith IBA treatment, and in root length with Ethrel treatment,were accompanied by decreases in the soluble carbohydrate concentration,particularly in stem bases.     

多效唑连用其它植物激素对水稻试管苗生长的影响

本实验采用继代多年的花培体细胞无性系Hu18再生绿芽(0.5mm)为起始材料,研究多效唑(MET)与其它激素配合使用对试管苗的调控作用,结果指出:(1)单独使用MET对绿芽生长有毒害作用,除2,4-D、GA,外,MET与适宜浓度的其它激素配合使用才能发挥增苗、壮苗作用,其中以MET与BA配合使用的培养效果最好,MET与NAA,C_2H_4配合使用的效果次之;(2)MET与其他激素配合使用不但能降低植株高度,促进根系发育,而且可以延长试管苗的保存时间;(3)MET与乙烯利配合使用能加速绿芽成苗速度,而与其他激素配合使则延缓绿芽成苗速度,如与2,4-D配合使用则延缓2,4-D对绿芽的脱分化进程;(4)在本实验条件下,以MET 2.5mg/L+BA 2mg/L+NAA 0.2mg/L配合使用有利根芽的协调生长。本文还从植株干物质累积,叶细胞结构,细胞活力等方面进行了探讨。     

Ethylene as a Mediator of Rubigan Biological Action in Cowpea Plants

Rubigan (a systemic fungicide) inhibited the growth of Rhizoctonia solani in vitro when used at concentrations of 6, 12 and 24 μg/ml respectively. Application of Rubigan as a soil drench significantly reduced the damping-off incidence on cowpea (Vigna sinensis) plants. Symptoms of growth retardation appearing on cowpea plants treated with Rubigan could be mimiced using an ethylene releasing compound (Ethrel). Ethrel at 10 and 20 μl/ml added to the soil around the seeds induced severe dwarfing as evidenced from measurements of plant length, dry weight and leaf area. Gas chromatographic analysis revealed that ethylene was released either from Rubigan mixed or not with the soil. Rates of ethylene production from soils drenched with Rubigan were relatively inferiorto those produced by authentic Rubigan solutions not added to the soil. Moreover, in all cases ethylene was released at rates proportional to the Rubigan concentrations applied. Factors involved in growth retardation of Rubigan-treated cowpea plants were discussed in the light of the possible interaction between ethylene and endogenous gibberellin levels.     

Genetic analysis of X-linked hybrid sterility in the house mouse

Hybrid sterility is a common postzygotic reproductive isolation mechanism that appears in the early stages of speciation of various organisms. Mus musculus musculus and Mus musculus domesticus represent two recently separated mouse subspecies particularly suitable for genetic studies of hybrid sterility. Here we show that the introgression of Chr X of M. m. musculus origin (PWD/Ph inbred strain, henceforth PWD) into the genetic background of the C57BL/6J (henceforth B6) inbred strain (predominantly of M. m. domesticus origin) causes male sterility. The X-linked hybrid sterility is associated with reduced testes weight, lower sperm count, and morphological abnormalities of sperm heads. The analysis of recombinant Chr Xs in sterile and fertile males as well as quantitative trait locus (QTL) analysis of several fertility parameters revealed an oligogenic nature of the X-linked hybrid sterility. The Hstx1 locus responsible for male sterility was mapped near DXMit119 in the central part of Chr X. To ensure full sterility, the PWD allele of Hstx1 has to be supported with the PWD allelic form of loci in at least one proximal and/or one distal region of Chr X. Mapping and cloning of Hstx1 and other genes responsible for sterility of B6–X^PWDY^B6 males could help to elucidate the special role of Chr X in hybrid sterility and consequently in speciation.     

Resolving the evolution of sterile worker castes: a window on the advantages and disadvantages of monogamy

Many social Hymenoptera species have morphologically sterile worker castes. It is proposed that the evolutionary routes to this obligate sterility must pass through a ‘monogamy window’, because inclusive fitness favours individuals retaining their reproductive totipotency unless they can rear full siblings. Simulated evolution of sterility, however, finds that ‘point of view’ is critically important. Monogamy is facilitating if sterility is expressed altruistically (i.e. workers defer reproduction to queens), but if sterility results from manipulation by mothers or siblings, monogamy may have no effect or lessen the likelihood of sterility. Overall, the model and data from facultatively eusocial bees suggest that eusociality and sterility are more likely to originate through manipulation than by altruism, casting doubt on a mandatory role for monogamy. Simple kin selection paradigms, such as Hamilton''s rule, can also fail to account for significant evolutionary dynamics created by factors, such as population structure, group-level effects or non-random mating patterns. The easy remedy is to always validate apparently insightful predictions from Hamiltonian equations with life-history appropriate genetic models.     

Promotion of Stomatal Opening by Indoleacetic Acid and Ethrel in Epidermal Strips of Vicia faba L

Indole-3-acetic acid (IAA), at concentrations of 0.01 to 1.0 millimolar, and ethephon (0.3% v/v Ethrel) promote stomatal opening when applied to epidermal peels of Vicia faba L. in light or dark. The effect of ethylene is seen by 30 minutes and maximal opening (over two times that of untreated controls) occurs after only 60 to 90 minutes in the light. Stomatal opening by IAA and Ethrel in both light and dark is prevented by 0.14 millimolar AgCl. It is suggested that the effect of added IAA, but not that of light, is linked to ethylene production. The possible role of ethylene in stomatal opening during fungal infection is discussed. The stomates of Vicia faba provide a new system to study the effects of ethylene on certain membrane-regulated processes.     

Changes in the Alkaloid Content of Developing Fruits of Tomato (Lycopersicon esculentum Mill.): II. EFFECTS OF ARTIFICIAL ACCELERATION AND RETARDATION OF RIPENING

Fruit ripening in normal red-, orange- and yellow-fruited cultivarsof tomato was accelerated by treatment with Ethrel and suchfruits had lower tomatine levels than untreated controls. Fruitsin which ripening was retarded by incubating under reduced pressurehad higher alkaloid levels than controls. In each case, fruitripeness (as measured by pigmentation) showed a strong negativecorrelation with fruit tomatine. Ethrel treatment of fruitsof the non-ripening mutants nor and rin caused only a smalldevelopment of carotenoid pigment but markedly enhanced tomatinedisappearance. Pigmentation and tomatine were again negativelycorrelated although the quantitative relationship differed.Under normal circumstances, tomatine disappearance from tomatofruits-is apparently governed by the physiological (cf. chronological)age of the fruit rather than by its growth or ripening characteristicsalone. Key words: Tomato, Fruit ripening, Acceleration, Retardation, Tomatine     

Hormonal regulation of sex expression in Momordica charantia

Sex expression in a monoecious cucurbit, Momordica charantia L. (long–fruited variety 'Karela') can be regulated by application of gibberellin A₃ (GA₃), indole-3-acetic acid (IAA) and 3-hydroxymethyl oxindole (HMO), an oxidation product of IAA, all of which promote female flowering. Both IAA and HMO accelerated ethylene evolution in the seedlings of this plant. While a low concentration of Ethrel promotes flowering, the effect was reversed with increased concentrations. Surprisingly, GA₃ was the most effective growth regulator in increasing, femaleness. In untreated plants, levels of endogenous GA-like substance increased progressively up to the age of 60 days, at which the ratio of male to female flowers was minimum.     

Estimation of mutagenicity and metabolic activation after recurrent exposures ofnicotiana tabacum L. var.xanthi to 14 pesticides

Recurrent application (17 administrations in 38 days) of 14 pesticides (Karathane FN 57, Fundazol 50 WP, Dithane M 45, Topsin M 70 WP, Perozin 75 B, Fademorf EK 20, Novozir MN 80, Metation E 50, Pirimor DP, Decemtion EK 20, Zeazin 50 DP, Fatex EK 80, maleic hydrazide and Ethrel) did not increase (with the exception of maleic hydrazide) the frequency of somatic mutations in a heterozygous chlorophyll mutant ofNicotiana tabacumL. var.xanthi n. c. None of the four tested pesticides (Fademorf EK 20, Decemtion EK 20, maleic hydrazide and Ethrel) were transformed in tobacco plants to a stable mutagenic or promutagenic product active in theSalmonella (Ames) mutagenicity assay.     

Further Characterization of the Odysseus Locus of Hybrid Sterility in Drosophila: One Gene Is Not Enough

Previously we mapped by genetical and molecular means a gene that contributes to hybrid-male sterility between Drosophila mauritiana and D. simulans to the cytological interval of 16D. In this report, we refine the mapping of this gene, Odysseus (Ods) and show that it can be delineated to a region the size of an average gene. We further demonstrate that, while Ods appears to be a discrete element, it requires other nearby gene(s) to be cointrogressed to confer full hybrid sterility effect. This observation is in agreement with the view that reproductive isolation between closely related species of Drosophila is usually caused by several genes of weak effect from the same species that interact strongly among themselves as well as with the foreign genetic background.