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Physiologische Reaktion zum Dürrestress der Bohnengenotypen (Phaseolus vulgaris L.) , die sich in Dürreresistenz unterscheiden
Get PDFDrought stress is a major constraint to common bean (Phaseolus vulgaris L.) production worldwide. Understanding the physiological basis of drought resistance may help to target the key traits that limit yield of the crop under drought situations. The objective of this study was to test the hypotheses that I) differences exist in biomass accumulation, yield and water-use efficiency among common bean cultivars developed for wider agro-ecological adaptation and inbred lines selected for specific adaptation to drought situations when subjected to drought stress; II) a drought-resistant genotype has a higher sink strength than a susceptible genotype and the difference between the genotypes is related to the ability to maintain assimilate synthesis and availability of assimilates for metabolism in the reproductive sink organs under drought stress; III) drought stress induces higher accumulation of ABA in sink leaves of a drought-susceptible genotype than in the leaves of a resistant genotype; and IV) relative to non-stressed plants, drought stress alters the protein pattern in a mature bean leaf.
Three adapted cultivars and three inbred lines of common bean were initially screened to assess seed yield-based drought resistance and water-use efficiency of the genotypes. A drought-resistant (SEA 15) and a susceptible genotype (Brown Speckled) were selected and used for subsequent experiments carried out thereafter. Drought stress was initiated at different growth stages (vegetative or reproductive phases) by withholding the amount of water applied in order to keep the moisture level at about 30% of the maximum water-holding capacity (WHC) of the soil. For control treatments, the soil moisture was maintained at 70% of the maximum WHC. Parameters related to growth, yield, water-use efficiency, leaf-water relations, gas-exchange, seed sink size, and the concentration of assimilates in various source and sink organs were determined. Changes in mature leaf proteins due to drought stress imposed during the vegetative phase were detected using 2D gel electophoresis.
Drought stress initiated during the reproductive phase significantly reduced the seed yields of the tested genotypes. However, seed yield reductions owing to the stress imposed were considerably higher for the old adapted cultivars than for the inbred lines selected for specific adaptation to drought conditions. With ca. 30 and 53% decrease in seed yield, SEA 15 and Brown Speckled were the most drought-resistant and susceptible genotypes, respectively. Drought stress initiated during different growth phases of the crop adversely affected biomass accumulation, although apparent genotypic differences were lacking. However, the harvest index of the drought-susceptible genotype (Brown Speckled) was reduced by about 29% due to drought, whereas that of SEA 15 remained unaffected. The maintenance of higher sink strength (larger numbers of pods and seeds per plant) under drought stress of SEA 15 was partly contributed by the higher efficiency of the genotype to remobilize biomass from vegetative parts to reproductive organs. SEA 15 maintained higher water-use efficiency (WUE) than Brown Speckled when subjected to drought stress. Relatively smaller transpiration rate (less water consumption), efficient stomatal regulation, faster vegetative biomass accumulation and higher seed yield production accounted for the observed higher WUE of the drought-resistant genotype. These features may confer a fitness advantage for drought-resistant inbred lines over drought-susceptible cultivars under drought conditions.
Drought stress commenced at the vegetative as well as reproductive growth phases decreased net photosynthetic rate of the bean genotypes differing in drought resistance. Drought-induced stomatal closure (limited availability of CO2) was the main factor responsible for the reduced carbon assimilation rate of both genotypes, although there was evidence of non-stomatal inhibition of photosynthesis for the drought-susceptible genotype. During the vegetative phase, drought-induced reductions in A corresponded with the decreases in leaf sugar concentrations of the bean genotypes. Thus, shortage of assimilate as a consequence of reduced carbon assimilation could be the growth-limiting factor during the vegetative phase. Similarly, drought initiated during the pod-filling stage reduced not only A but also the concentrations of sucrose in the leaves and seeds of Brown Speckled demonstrating that reproductive sink establishment and yield of the susceptible genotype was primarily source-limited. Moreover, higher pod sucrose to hexose sugars ratio found for Brown Speckled demonstrates that the capability to utilize the imported sucrose was inhibited due to drought. Drought stress initiated during the same period did not alter the availability of assimilates for the drought-resistant genotype (SEA 15) both at source and sink levels. The results suggest that at whole plant level of SEA 15, total A is less affected than total carbohydrate demand because the genotype was able to adjust sink demand with source supply under drought conditions.
In addition to assimilate synthesis, availability and metabolism, the differences found in drought-induced ABA accumulation and the decrease in pod water concentration could also be responsible for the differential drought-sensitivity of the bean genotypes. Drought stress also negatively affected seed starch accumulation of the bean genotypes mainly through arresting the expansion growth of starch granules (amyloplasts). In summary, although apparent genotypic differences were observed for sink strength under drought stress, the underlying variation in sink establishment and ultimate yield of the bean genotypes reside in the capacity to supply assimilates by the source (source-strength).
Drought stress imposed during the vegetative phase of Brown Speckled resulted in the differential expression of ca. 42% of the total leaf proteins detected. Out of these proteins, 1.5% disappeared, 1.8% were newly produced, 23.5% were down-regulated and 15.1% were up-regulated in response to drought. The sizes of the drought-responsive proteins were widely variable.Weltweit ist Dürrestress der stärkste ertragslimitierende Produktionfaktor für die Bohne (Phaseolus vulgaris L.). Das Verständis der physiologischen Grundlagen der Dürreresistenz trägt dazu bei Ertragsminderungen bei Trockenheit zu reduzieren. Ziel der vorliegenden Arbeit war es, die nachstehenden Hypothesen zu prüfen: I) Bestehen genotypische Unterschiede in der Biomasseproduktion von Bohnensorten und Bohnenlinien, die aufgrund ihrer Biomasseakkumulation und Wassernutzungseffizienz unter Dürre selektiert wurden? II) Hat ein trockenresistenter Genotyp eine größere Sinkkapazität als ein trockenempfindlicher Genotyp, und steht dieser Unterschied zwischen den Genotypen in Zusammenhang zur Assimilatsynthese und zum Vermögen bei Dürrestress die Assimilate in den reproduktiven Sinkorganen zu metabolisieren? III) Verursacht Dürrestress eine höhere Akkumulation von ABA in den Sinkblättern eines dürreempfindlichen Genotyps als in den Sinkblättern eines dürreresistenten Genotyps? IV) Verändert ein Dürrestress das Proteinmuster in einem vollentwickelten Bohnenblatt?
Drei angepasste Sorten und drei Linien von Bohnen wurden zuerst selektiert, um eine auf den Samenertrag begründete Dürreresistenz und Wassernutzungseffizienz der Genotypen festzustellen. Für die folgenden Versuche wurde ein dürreresistenter (SEA 15) und ein dürreempfindlicher Genotyp (Brown Speckled) ausgewählt. Dürrestress wurde in verschiedenen Wachstumsphasen (vegetative oder reproduktive Phase) durch Wasserentzug appliziert, so dass die Bodenfeuchte bei ca. 30% von der maximalen Wasserhaltekapazität (WHK) des Bodens lag. In der Kontrolevariante wurde die Bodenfeuchte auf 70% der maximalen WHK eingestellt. Bezogen auf das Wachstum wurden die Parameter Ertrag, Wassernutzungseffizienz, Wassergehalt des Blattes, Gasaustausch, Sink-Größe der Samen und die Assimilat-Konzentration in verschiedenen Organen von Source und Sink bestimmt. Eine mögliche Änderung des Proteinmusters in den vollentwickelten Blättern infolge von Dürrestress wurde mit der 2D- Gelelektrophorese analysiert.Ein während der reproduktiven Phase induzierter Dürrestress führte zur Verminderung der Samenerträge bei den getesteten Genotypen. Die aufgrund von Dürrenstress beobachtete Reduktion im Samenertrag war bei der alten angepassten Sorte stärker ausgeprägt als bei den Inzuchtlinien, die auf Dürreresistenz selektiert worden waren. Mit ca. 30 und 53% Abnahme im Samenertrag war SEA 15 bzw. Brown Speckled der jeweilig dürreresistenteste und dürreempfindlichste Genotyp. Dürrestress, der während der unterschiedlichen Wachstumphasen induziert wurde, beeinflusste die Biomasseakkumulation ungünstig, obwohl deutliche genotypische Unterschiede verlagen. Jedoch wurde der Ernteindex des dürreempfindlichen Genotyps (Brown Speckled) um ungefähr 29% aufgrund von Dürre verringert, während der von SEA 15 unbeeinflusst blieb. Bei Dürrestress trug die Sinkgröße (größere Anzahl von Hülsen und Samen pro Pflanze) von SEA 15 dazu bei, dass Assimilate effizienter aus der vegetativen Biomasse in die reproduktiven Organen verlagert wurden. Bei Dürrestress zeigte SEA 15 eine höhere Wassernutzungseffizienz (WUE) als Brown Speckled. Die höhere WUE von SEA 15 beruhte auf einer kleineren Transpirationsrate (geringer Wasserverbrauch), effizienten Stomataregelung, einem raschen vegetativen Wachstum und einem hohen Samenertrag. Diese Eigenschaften könnten die Dürreresistanz der dürreresistenten Genotypen erklären.
Dürrestress, der während der vegetativen sowie reproduktiven Wachstumsphasen induziert wurde, reduzierte die Nettophotosyntheserate (A) der Bohnengenotypen, die sich in der Dürrenresistenz unterschieden. Dürreverursachtes Stomataschließen (limitierende Verfügbarkeit von CO2) war der Hauptfaktor, der für die reduzierte Assimilationsrate beider Genotypen verantwortlich war. Dennoch gab es Hinweise auf eine nicht-stomatäre Hemmung der Photosynthese beim dürreempfindlichen Genotyp. Während der vegetativen Phase stand die durch Dürre bedingte Abnahme von A mit der Reduktion der Blattzuckerkonzentrationen der Bohnengenotypen in Beziehung. Folglich könnte ein Assimilatmangel, der durch eine verminderte CO2-Assimilation bedingt war, ein Grund für die Wachstumshemmung in der vegetativen Phase sein. Dürrestress, der während der Hülsenfüllungsphase induziert wurde, reduziert nicht nur Nettophotosyntheserate, sondern auch die Saccharosekonzentrationen in den Blättern und in den Samen von Brown Speckled. Diese Ergebnisse zeigen, dass die Anlage von reproduktiven Sinkorganen und der Ertrag des empfindlichen Genotyps hauptsächlich vom Source begrenzt waren. Ferner weist das höhere Verhältnis der Saccharosekonzentration zur Hexosekonzentration in den Hülsen von Brown Speckled daraufhin, dass die Kapazität zur Nutzung von importierter Saccharose durch Trockenheit gehemmt wurde. Die Ergebnisse deuten darauf hin, dass bei SEA 15, bezogen auf die Gesamtpflanze, Nettophotosyntheserate weniger beeinflusst wurde als der Gesamt-Kolenhydratbedarf. Dieser Genotyp ist in der Lage, die Sinknachfrage durch eine Sourceversorgung auszugleichen.
Neben Synthese, Verfügbarkeit und Stoffwechsel von Assimilaten, könnte die Dürreempfindlichkeit der Bohnengenotypen mit einer dürreinduzierten ABA- Akkumulation und einer Abnahme der Hülsenwasserkonzentration erklärt werden. Dürrestress reduzierte die Stärkeakkumulation in den Samen von beiden Bohnengenotypen infolge einer Wachstumshemmung der Stärkekörnchen (Amyloplasten). Zusammenfassend ist festzustellen, dass, obwohl deutliche genotypische Unterschiede in der Sinkgröße unter Dürrestress beobachtet wurden, die Variation in der Sinkanlage und der Ertrag der Bohnengenotypen besonders auf dem Vermögen des Sources beruht Assimilate bereitzustellen (Sourcegröße).
Der während der vegetativen Phase von Brown Speckled induzierte Dürrestress führte zu einer differentiellen Expression von ca 42% der bestimmten Blattproteine. Von diesen Proteinen waren 1,5% verschwunden, 1,8% neu synthetisiert, 23,5% herunterreguliert und 15,1% hochreguliert. Die Größe der Proteine, die infolge von Dürre auftraten, war sehr variabel
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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