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Regulation of ethylene biosynthesis in vegetative tissues of white clover (Trifolium repens L.) during water deficit : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Biology, Institute of Molecular Biosciences, Massey University, Palmerston North, New Zealand
Full text linkThe investigation in this thesis is divided into two parts. In the first part, the expression and accumulation of 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO), the enzyme which catalyses the final step of ethylene biosynthesis in higher plants, is examined during exposure of white clover (Trifolium repens L.) to a water deficit. The second part of this thesis is focused on the identification and characterisation of a water-deficit-associated ACC synthase (ACS), the enzyme which catalyses the production of ACC.
In the first part, two white clover varieties with differing sensitivity to water deficit, a drought-tolerant Tienshan ecotype and a drought-sensitive Grasslands Challenge cv. Kopu II cultivar were exposed to two water deficit treatments: one cycle of water deficit (designated non-prestressed; NPS) and a water deficit, a rehydration period and then a second water deficit treatment (designated pre-stressed; PS) in the New Zealand Climate Environment Laboratory (NZCEL). Treatments were terminated when the petiole elongation rate (PER) in the first fully-expanded leaf reached zero. Water relations, growth responses, the expression of the white clover ACO genes, TR-ACO1 TR-ACO2 and TR-ACO3 and the accumulation of two of the corresponding proteins, TR-ACO1 and TR-ACO2, were then examined.
The soil water content (SWC) and leaf water potential (LWP) measured in both varieties and in both water deficit treatments declined progressively. The rate of decline in SWC and LWP was slower in the Tienshan ecotype with no difference between the NPS and PS treatments. However, the LWP in the Tienshan ecotype at the point at which the PER ceased was less negative (ca. -1.4 MPa) compared to Kopu (ca. -1.7 MPa). In addition, the decline in the PER differed between NPS- and PS-treated Kopu. In the NPS-treated Kopu, the PER was maintained at a high rate when plants were exposed to SWC above 18%, but declined sharply as the SWC declined further. However, in the PS-treated Kopu, the PER declined more progressively in a similar pattern to that determined for NPS- and PS-treated Tienshan.
Expression of TR-ACO1 and accumulation of TR-ACO1 was observed in the apical structure of the stolon. As the water deficit progressed, no significant alteration in TR-ACO1 expression and TR-ACO1 protein accumulation was observed in the apical structures of both the NPS- and PS-treated Tienshan ecotype suggesting some degree of protection of the meristem tissues in this more drought-tolerant variety. However, a discernable decline in expression of TR-ACO1 and accumulation of TR-ACO1 protein was observed in the NPS-treated Kopu suggesting some degree of tissue injury in this more drought-susceptible variety. However, after the pre-stress (PS) treatment, no real changes in TR-ACO1 expression and TR-ACO1 protein accumulation were observed, in common with the observations for the NPS- and PS-treated Tienshan ecotype suggesting that meristem protection may now be occurring. The results suggest further that the pre-stress treatment of the more drought-susceptible Kopu may result in a degree of acclimation to the water deficit.
For the first-fully expanded leaves, expression of two transcripts, TR-ACO2 and TR-ACO3 and accumulation of TR-ACO2 protein was monitored as the SWC decreased. The expression of TR-ACO2 and accumulation of TR-ACO2 decreased as the water deficit progressed in both the NPS- and PS-treated Tienshan ecotype and correlated with the decrease in PER. By contrast, in the NPS-treated Kopu, TR-ACO2 expression and TR-ACO2 protein accumulation increased, but again, after a period of pre-stress, TR-ACO2 expression and TR-ACO2 accumulation decreased, in common with the Tienshan ecotype. Again, the pre-stress treatment of the drought-susceptible Kopu may result in a degree of acclimation to the water deficit such that the responses become similar to those observed in the more drought-tolerant Tienshan ecotype. However, in both NPS- and PS-treated Tienshan and Kopu there was no significant alteration in the expression of TR-ACO3 in the first fully-expanded leaf.
The expression of TR-ACO2 and TR-ACO3 and accumulation of TR-ACO2 protein were also observed in the second fully-expanded leaves (an older tissue). Again similar patterns in the expression of TR-ACO2 and TR-ACO3 and accumulation of TR-ACO2 protein were observed in both NPS- and PS-treated Tienshan and Kopu. In these leaves, expression of TR-ACO2 and accumulation of TR-ACO2 protein
decreased as the water deficit progressed, but expression of TR-ACO3 increased as the water deficit decreased to less than 10%. These results suggest that responses of younger tissues (apical structure; first-fully expanded leaf) maybe the critical determinant for the tolerant (or otherwise) of white clover plants to water deficit.
In the second part of this thesis, four ACS genes were identified from the Tienshan ecotype exposed to water deficit and designated TR-ACS-T. Three of these were similar to previously identified TR-ACS genes from Grasslands Challenge genotype 10F while the fourth was a novel gene designated TR-ACS4-T. TR-ACS4-T is 64%, 64% and 63% homologous to TR-ACS1-T, TR-ACS2-T and TR-ACS3-T, respectively in terms of nucleotide sequence. In the GeneBank database, TR-ACS4-T shares highly homology to ACC synthase sequences from a wide range of tissues including seedlings and fruit tissues, in addition to a high homology to ACS genes induced in auxin-, wounding- and ethylene-treated tissues.
The pattern of TR-ACS4-T expression observed during leaf development suggests that the gene is expressed initially in the apical structures and in the newly initiated leaves, and then again in the later mature leaves and those at the onset of senescence. Expression decreases again during senescence. TR-ACS4-T expression is not altered by water deficit, but is induced by both ethylene and NAA treatment, but the auxin-induced TR-ACS4-T is mediated by ethylene treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Pengaruh Kosentrasi dan Frekuensi Pemberian Pupuk Hayati Bio-EXTRIM Terhadap Pertumbuhan dan Hasil Tanaman Wortel (Daucus carota L.) dalam Pot di Dataran Rendah
Full text linkThis study aimed to determine the effect of the concentration and frequency of Bio-EXTRIM biofertilizer applications and their interactions on the growth and yield of carrot (Daucus carota L.) plants cultivated using pots in the lowland. This research was conducted in the rice fields of Siren Hamlet, East Rumbuk Village, East Lombok sub-district, from March toJune 2019, and arranged according to the Randomized Block Design (RBD) factorial with two factors. The first factor was the concentration of  Bio-EXTRIM and the second factor was the frequency of Bio-EXTRIM applications; each consisted of 3 levels and thus resulted in 9 interractio. The interraction were: concentration of 0.25% with 4 times application, concentration of 0.25% with 5 times application, concentration of 0.25% with 6 times application, concentration of 0.5% with 4 times application, concentration of 0.5% with 5 times application, concentration of 0.5% with 6 times application, concentration of 1% with 4 times application, concentration of 1% with 5 times application, and concentration of 1% with 6 times application. The results showes that the concentration of Bio-EXTRIM biofertilizer had significant effect on the rate of carrot leaf stalks growth, with concentration of 0.25% had the highest leaf stalk growth rate. The frequency of Bio-EXTRIM biofertilizer applications influenced the dry weight of leaf biomass, the middle diameter of the carrot root and the sugar content of the carrot root. The highest dry weight of leaf biomass and diameter of the tuber were obtained in carrot plants treated with Bio-EXTRIM biofertilizer for 4 times, while the sweetest tubers were obtained in carrot plants treated with Bio-EXTRIM biofertilizer for 6 times. However, there was no interaction between the concentration and frequency of Bio-EXTRIM biofertilizers in influencing the growth and yield of carrots grown in the pots in the lowland
PERTUMBUHAN BIBIT RUMPUT LAUT (Kappaphycus alvarezii) HASIL KULTUR JARINGAN DENGAN BERAT BIBIT YANG BERBEDA
No full textThis study conducted to determine the effect of tissue culture seed weight on growth of Kappaphycus alvarezii and to determine the optimal weight. This study used a Completely Randomized Design (RAL) consisting of 4 treatments using with different seed weight. The treatment were P1: 50 gr, P2:75 gr, P3:100 gr, P4:125 gr. Treatments ware repeated 4 times (4 rafts). Data of obtained research variables od, be tabulated using excel microsof and be analyzed using analysis of variance and be continued tested by using Least Significant Difference (LSD) test. The highest weight gain result was obtained at weight of 125 gr and the highest growth rate at 50 gr, where in each of these treatments had an effect (p <0.05) seed weight on growth. This related to the competition of each individual seaweed in absorbing sunlight for photosynthesis. Weight of seed is one of the technical factors that can affect the growth of seaweed. Density in each seaweed bonds need to be so that it can cause seaweed fall.Penelitian ini bertujuan untuk mengetahui pengaruh berat bibit kultur jaringan yang berbeda terhadap pertumbuhan rumput laut Kappaphycus alvarezii dan untuk mengetahui berat bibit hasil kultur jaringan yang optimal untuk pertumbuhan rumput laut jenis Kappaphycus alvarezii. Penelitian ini menggunakan Rancangan Acak Lengkap (RAL) yang terdiri atas 4 perlakuan menggunakan bibit hasil kultur jaringan dengan perbedaan berat bibitnya.Perlakuan tersebut adalah P1 : bibit dengan berat 50 gr, P2 : bibit dengan berat 75 gr, P3 : bibit dengan berat 100 gr, P4 : bibit dengan berat 125 gr. Perlakuan diulang sebanyak 4 kali (4 rakit). Data variabel penelitian yang diperoleh, ditabulasi menggunakan mikrosof excel dan dianalisis menggunakan analisis sidik ragam (ANOVA) pada taraf nyata 5%, kemudian dilakukan uji lanjut dengan uji Least Significant Difference (LSD). Hasil pertambahan berat tertinggi didapat pada berat 125 gr dan laju pertumbuhan tertinggi pada berat 50 gr, dimana pada setiap perlakuan ini berpengaruh (p<0.05) berat bibit terhadap pertumbuhan. Hal ini berkaitan dengan persaingan setiap individu rumput laut dalam menyerap cahaya matahari untuk fotosintesis. Berat bibit merupakan salah satu faktor teknis yang dapat berpengaruh terhadap pertumbuhan rumput laut dan juga jumlah kepadatan disetiap ikatan rumput laut perlu diperhatikan agar tidak terlalu padat sehingga dapat menyebabkan rumput laut rontok
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