Vernalisation,Licht und Alter beiArabidopsis thaliana (L.) Heynh

Zusammenfassung Pflanzen der winterannuellenArabidopsis-RasseStockholm, 0–91 Tage vor Beginn einer 40tägigen Lichtvernalisation ausgesät, blühten am frühesten, wenn sie vor der Vernalisation bei geringerer und nach der Vernalisation bei höherer Lichtintensität aufgewachsen waren. Durch die umgekehrte Kombination (höhere Intensität vor, geringere nach der Kältebehandlung) wurde der Blühbeginn am stärksten verzögert.Unabhängig von den Lichtverhältnissen vor, während und nach der Kältebehandlung sprachen unter den Bedingungen dieses Versuches 7 Tage alte Keimlinge auf eine 40tägige Vernalisation am wenigsten an. Der Zeitpunkt geringster Vernalisierbarkeit wird also auch nicht durch die vor und nach der Vernalisation herrschende Lichtintensität bestimmt.Mit 2 Textabbildungen     

Die Anwendung von Embryokultur,Vernalisation und Colchicin zur Herstellung amphipolyploider Gramineen-Bastarde

Ohne Zusammenfassung     

Studies in Vernalisation of Cereals: XIV. The Thermal Reactions in Vernalisation

Vernalisation of Petkus winter rye can be reversed by high temperature.Such devernalisation was prevented or diminished by a periodat the ‘neutral’ temperature (about 13° C) immediatelyafter vernalisation, by weak light, or by restricting the growthof the seedlings by limiting the water-supply. Before vernalisationwas completed, each additional week at low temperature approximatelyhalved the percentage devernalisation possible. Prolonging theheat treatment after vernalisation led to a secondary accelerationof flowering. By subjecting intact grain and excised embryosto various alternations of low and high temperature, data wereobtained from which the Q₁₀ of the devernalising process wasestimated to be approximately 4, and independent of the presenceof the endosperm. Exposure to high temperature before vernalisation(pre-devernalisation) reduced the effect of the cold treatmenton intact grain and, to a much less extent, on excised embryos,but did not prevent completion of the process accelerating floweringif low-temperature treatment was prolonged.     

Some Morphological Responses of Cereal Seedlings to Vernalisation

Statements in the literature that vernalisation treatments modifythe growth of cereal seedlings are confirmed; in particularthe coleoptile and early leaves are shortened and hair developmenton the leaf sheaths is suppressed. While there is a definiterelationship between the degree of these responses and the durationof low-temperature treatment, this is not reliable measure offlower induction, and there is no evidence that they are conditionedby the same process. Devernalisation by heat accentuates ratherthan reverse the morphological responses; moreover, in springrye early flowering is inherent, though the morphological responsesapproach those of unvernalised winter grain.     

Studies in Vernalisation of Cereals: XV. After-effects of Temperature and Drying during Seed Ripening and the Origin of the Vernalisation Requirement in Petkus Winter Rye

Experiments are described which were designed to test whetherthe unvernalised condition of winter rye grain produced by fullyvernalised parent plants is due to de-vernalisation occurringduring maturation and ripening of the seed. The results showclearly that drying of the grain does not account for the un-vernalisedcondition. Parent ears exposed from the time of their emergenceto a range of non-vernalising temperatures (12–20°C), i.e. including ‘neutral’ levels which are neithervernalising nor de-vernalising, still produced unvernalisedgrain. Even plants raised from grain which had been developedat mildly vernalising temperatures (9° C) benefited fromfurther cold treatment applied during their early growth. Itappears, therefore, that the vernalisation requirement in winterrye arises very early in the formation of the seed, i.e. possiblyat meiosis or fertilisation, and that there is no subsequenttransmission of the vernalisation stimulus from the parent plant. Additional observations on plant height, ear size, &c.,also indicate marked effects of temperature and daylength treatments.     

Vernalisation of sugar beet seed on the mother plant in Western European and mediterranean climates

The calculation of the vernalisation response of sugar beet seed on the mother plant is given in detail, using air temperature data from Sweden, England, France, Italy and Turkey. It is pointed out that vernalisation is only one of a variety of other factors, meteorological agronomic, commercial and social, which affect the choice of seed production areas. Some of these other factors are described in outline.     

Vernalisation of Winter Rye by Negative Temperatures and the Influence of Vernalisation upon the Lamina Length of the First and Second Leaf in Winter Rye, Spring Barley, and Winter Barley

The lowest effective temperature observed for vernalising PetkuaWinter Rye was –4.5° C., whereas –6° to–10° C. did not induce any hastening of flowering.Seedlings of 20–25 mm. length were as susceptible to –3°C. as seeds in the stage at which the radicle had just brokenthrough the pericarp. Vernalising temperatures alternating between7 days +1° C. and 3 days –3° C. were as effectiveas continuous treatment by +1° C. The lamina length of thefirst and second leaf is shortened by raising the vernalisingtemperatures from –3° C. to +3° C. and also isfurther shortened by prolonging the vernalisation period inwinter rye and winter barley. No progressive shortening of thelamina length, however, was observed in spring barley when treatedlike winter barley. This suggests a direct dependence of thelamina length of the first and second leaf on the degree ofvernalisation reached in the embryo.     

Studies in Vernalisation: XII. The Reversibility by High Temperature of the Vernalised Condition in Petkus Winter Rye

The reversibility of vernalisation in Petkus winter rye hasbeen studied in detail, by using alternating periods, duringgermination, of low and high temperature of varying durations.The degree of devernalisation by exposure to subsequent hightemperature varies with the initial duration of vernalisationand becomes progressively less as vernalisation proceeds. Aquantitative method of studying these effects is described,and a revised schema of the dynamic aspects of vernalisationput forward.     

25. Gottfried Günther: Die Wirkung von Chlorcholinchlorid (CCC) auf die Vernalisation von Winter- and Sommerweizen

Zugabe von CCC während der Vernalisation von Winter- und Sommergetreide verzögert in Abhängigkeit von Pflanzenart, Wirkstoffkonzentration und Anwendungstermin den Eintritt der generativen Entwicklung. Die Beobachtung einer Entwicklungshemmung auch bei Sommergetreide schließt eine spezifische vernalisationshemmende Wirkung von CCC aus.     

Studies in Vernalisation of Cereals: XIII. Photoperiodic Control of Stages in Flowering between Initiation and Ear Formation in Vernalised and Unvernalised Petkus Winter Rye

The photoperiodic reactions of spring rye and vernalised andunvernalised winter rye have been studied in detail and interpretedin terms of a schema presented in earlier papers. Vernalisationtreatments ranging from 0 to 13 weeks were used and three daylengths(continuous light, C.L.; normal days, L.D.; 10-hr. days, S.D.),and the interaction effects of these factors were studied onthe following developmental features: time to initiation offlowering and to ‘double-ridge’ formation; progressof differentiation and growth rate of the apex of the main shootbefore and after initiation. Systematic dissections of the apexwere carried out to obtain data for this study. The validityof the concept of ‘minimal leaf number’ was re-examinedand confirmed by using dwarf embryos with subnormal numbersof primordia at germination. Unvernalised winter rye was shownto behave as a short-day plant before flower initiation sincephotoperiodic induction by short days is annulled by interruptingthe dark period by a short light period at low intensity. Theeffect of exposure of a single leaf to continuous light, whilethe remainder of the plant was kept in short days, has beenshown to be transmitted to the apex and hastens both flowerinduction and spikelet development in fully vernalised rye.Vernalised winter rye and spring rye thus behave as long-dayplants.     

Evolution des Teneurs en Acides Chlorogénique et "Isochlorogénique' au Cours du Traitement de Vernalisation des Racines de Cichorium intybus

In a cold-requiring variety of endive (chicory, Cichorium intybus L. ev. Witloof) we could demonstrate a relationship between the variations in the content of chlorogenic acid during the cold treatment of the roots and their disposition to produce flowers in vitro. An increase in the level of chlorogenic acid in the roots preceded the development of their aptitude to form flower buds. In addition, the three main forms of “isochlorogenic’ acid are present in the roots of this cultivar: 3,5-dicaffeoyl-quinic acid, 3,4-dicaffeoyl-quinic acid, and traces of 4,5-dicaffeoyl-quinic acid. The variations in the levels of chlorogenic and “isochlorogenic’ acids indicate that part of the chlorogenic acid (3-caffeoyl-quinic acid) is converted to 3,5-dicaffeoyl-quinic acid.     

Studies in the Vernalisation of Cereals. IV: The Effect of Preliminary Soaking of the Grain on the Growth and Tropic Responses of the Excised Embryo of Winter Rye

Rye grains were soaked for various periods and the effect onthe subsequent growth of the excised embryo (grown on sucroseagar) studied. Soaking the grain for as short a period as two hours producesincreased growth of both roots and shoots in the excised embryo.This increase takes place irrespective of whether the embryois grown in light or darkness and is still manifested twentydays after the excision of the embryo. Production of lateral roots, both in light and darkness, andof anthocyanins in etiolated embryos is also increased by preliminarysoaking. Preliminary soaking of the grain has a marked accelerating effecton the tropic responses of the excised embryo. Concentration of sugar and duration of prelutllnary soakingboth effect the growth of the excised embryo, but neither constitutesa simple controlling factor in this growth. It is concluded that during the preliminary soaking, both auxinand a ‘regulator’ controlling its production anddistribution, enter the embryo from the endosperm and aleuronelayer.     

Plasmolyse und Deplasmolyse und ihre Beeinflussung durch Salze und durch die Wasserstoffionenkonzentration

Ohne Zusammenfassung     

Klinik und Genetik syndromaler und nichtsyndromaler Kraniosynostosen

With an incidence of 1:2000–1:3000 births, craniosynostoses are among the most common craniofacial anomalies. Growth inhibition caused by premature fusion of one or more cranial sutures can lead to severe deformities of the skull and facial skeleton. Besides the severe aesthetic problems for the patient, it also has important clinical consequences. These may include raised intracranial pressure, optic nerve atrophy, respiratory, and developmental disorders. Despite major efforts, causative genes (e.g., FGFR1-3, TWIST1) have been detected for only a portion of the autosomal dominantly inherited craniosynostosis syndromes. The etiology of non-syndromic craniosynostosis still remains unclear. The application of next generation sequencing technologies will probably lead to the identification of additional causative genes underlying at the least syndromic forms of craniosynostosis in upcoming years. Due to their clinical complexity, particularly the syndromic forms of craniosynostosis require interdisciplinary care. The only treatment option currently available is craniofacial surgery, which in the long term often fails to remedy the genetically determined pathological growth pattern of complex syndromic craniosynostoses.