Call number: LD2668 .T4 1959 E41

Call number: LD2668 .T4 1960 D73

LD2668 .T4 1962 S57

BACKGROUND:Tomato leaf curl Sudan virus (ToLCSDV) is a single-stranded DNA begomovirus of tomato that causes downward leaf curl, yellowing, and stunting. Leaf curl disease results in significant yield reduction in tomato crops in the Nile Basin. ToLCSDV symptoms resemble those caused by Tomato yellow leaf curl virus, a distinct and widespread begomovirus originating in the Middle East. In this study, tomato samples exhibiting leaf curl symptoms were collected from Gezira, Sudan. The associated viral genome was molecularly characterized, analyzed phylogenetically, and an infectious clone for one isolate was constructed.FINDINGS:The complete genomes for five newly discovered variants of ToLCSDV, ranging in size from 2765 to 2767-bp, were cloned and sequenced, and subjected to pairwise and phylogenetic analyses. Pairwise analysis indicated that the five Gezira isolates shared 97-100% nucleotide identity with each other. Further, these variants of ToLCSDV shared their highest nucleotide identity at 96-98%, 91-95%, 91-92%, and 91-92% with the Shambat, Gezira, Oman and Yemen strains of ToLCSDV, respectively. Based on the high maximum nucleotide identities shared between these ToLCSDV variants from Gezira and other previously recognized members of this taxonomic group, they are considered isolates of the Shambat strain of ToLCSDV. Analysis of the complete genome sequence for these new variants revealed that they were naturally occurring recombinants between two previously reported strains of ToLCSDV. Finally, a dimeric clone constructed from one representative ToLCSV genome from Gezira was shown to be infectious following inoculation to tomato and N. benthamiana plants.CONCLUSION:Five new, naturally occurring recombinant begomovirus variants (>96% shared nt identity) were identified in tomato plants from Gezira in Sudan, and shown to be isolates of the Shambat strain of ToLCSDV. The cloned viral genome was infectious in N. benthamiana and tomato plants, and symptoms in tomato closely resembled those observed in field infected tomato plants, indicating the virus is the causal agent of the leaf curl disease. The symptoms that developed in tomato seedlings closely resembled those observed in field infected tomato plants, indicating that ToLCSDV is the causal agent of the leaf curl disease in Gezira.

<p>Closely related populations or species often occupy ecologically disparate habitats. Adaptation to new habitats can maintain genetic variation within a species or eventually lead to speciation. Local adaptation to different environments has been repeatedly demonstrated in plants and animals, however the traits and genes that underlie this adaptation are poorly understood. This is because many traits differ between divergent populations and species. One way to solve this problem is to separate a trait from its genetic background through genetic manipulation and look for differences in fitness between genetically manipulated individuals. </p><p>My dissertation focuses on investigating the traits and genes that allow two species of Monkey flower, Mimulus laciniatus and Mimulus filicifolius, to survive in a unique habitat. Most closely related Mimulus species, such as M. guttatus, occur in streams and seeps, but M. laciniatus and M. filicifolius have each colonized a harsh granite outcrop environment. Another unique characteristic that both these species share is a lobed leaf shape. Because of the physiological properties of lobed leaves they should be adaptive in a dry, exposed granite outcrop. M. laciniatus also flowers earlier than nearby M. guttatus and is a small flowered self-fertilizing species while M. guttatus has large flowers and is highly outcrossing. Early flowering allows plants to escape the onset of seasonal drought while a self-fertilizing mating system and small flower size is often correlated with the occupation of harsh habitats. </p><p>In chapter one I describe a new granite outcrop endemic species of Mimulus, M. filicifolius based on morphological divergence from M. laciniatus. M. filicifolius was previously categorized as M. laciniatus but it is geographically disjunct and its leaves are more finely dissected (Sexton, Ferris, and Schoenig 2013). In the second chapter I explore whether M. filicifolius is genetically divergent and reproductively isolated from M. laciniatus using genetic sequence, microsattelite, and hybrid fertility data from four members of the M. guttatus species complex with highly overlapping geographic ranges: M. guttatus, M. nasutus, M. lacinaitus, and M. filicifolius. In the third chapter I investigate the genetic basis of leaf shape differences in three members of the M. guttatus species complex, M. laciniatus, M. nudatus, and M. guttatus using bulk segregant analysis to map quantitative trait loci. In the fourth and final chapter I examine the genetic basis of flowering time, floral size, and leaf shape divergence between sympatric M. guttatus and M. laciniatus populations in a common garden using quantitative trait locus (QTL) mapping, phenotypic selection on flowering time, flower size, and leaf shape in M. laciniatus x M. guttatus hybrids in a reciprocal transplant experiment in the field, and whether QTL's from my common garden experiment overlap fitness QTL's in the field by genotyping hybrid individuals that survived to flower in the field.</p> / Dissertation

In a minimal medium supplemented with glucose and yeast extract, the optimum pH for the growth of C. poinsettias was found to be 7.5. The organism requires thiamine, biotin, and pantothenic acid for growth. No absolute requirement was found for any amino acid, purine or pyrimidine although an amino acid mixture was stimulatory. Casamino acids could be substituted for the synthetic amino acid mixture. Yeast extract provided an additional factor(s) necessary for maximal growth. The results suggest that the unknown factor found in yeast extract might be purified by a combination of solvent extraction, and adsorption and elution from charcoal.

The thesis focuses on segmentation of images with leaves of woody species. The main aim was to investigate existing image segmentation methods, choose suitable method for given data and implement it. Inputs are scanned leaves and photographs of various quality. The thesis summarizes the general methods of image segmentation and describes algorithm that gives us the best results. Based on the histogram, the algorithm decides whether the input is of sufficient quality and can be segmented by Otsu algorithm or is not and should be segmented using GrowCut algorithm. Next, the image is improved by morphological closing and holes filling. Finally, only the largest object is left. Results are illustrated using generated output images. Powered by TCPDF (www.tcpdf.org)

Doctor of Philosophy / Department of Plant Pathology / Erick D. DeWolf / Stripe rust (caused by Puccinia striiformis f. sp. tritici) and leaf rust (caused by Puccinia triticina) are the top two diseases of winter wheat (Triticum aestivum) with a 20-year average yield loss of 4.9% in Kansas. Due to the significant yield losses caused by these diseases, the overall objective of this research was to identify environmental variables that favor stripe and leaf rust epidemics. The first objective was to verify the environmental conditions that favor P. triticina infections in an outdoor field environment. Wheat was inoculated with P. triticina and exposed to ambient weather conditions for 16 hours. Number of hours with temperature between 5 to 25°C and relative humidity >87% were highly correlated and predicted leaf rust infections with 89% accuracy. The results of this outdoor assay were used to develop variables to evaluate the association of environment with regional leaf rust epidemics. Before regional disease models can be developed for a forecast system, suitable predictors need to be identified. Objectives two and three of this research were to identify environmental variables associated with leaf rust and stripe rust epidemics and to evaluate these predictors in models. Mean yield loss on susceptible varieties was estimated for nine Kansas crop reporting districts (CRD’s). Monthly environmental variables were evaluated for association with stripe rust epidemics (>1% yield loss), leaf rust epidemics (>1% yield loss), severe stripe rust epidemics (>14% yield loss) and severe leaf rust epidemics (>7% yield loss) at the CRD scale. Stripe rust and leaf rust epidemics were both strongly associated with soil moisture conditions; however, the timing differed between these diseases. Stripe rust epidemics were associated with soil moisture in fall and winter, and leaf rust epidemics during winter and spring. Severe stripe rust and leaf rust epidemics were associated with favorable temperature (7 to 12°C) and temperature (15 to 20°C) with relative humidity (>87%) or precipitation in May using tree-based methods of classification, respectively. The preliminary models developed in this research could be coupled with disease observations and varietal resistance information to advise growers about the need for foliar fungicides against these rusts in Kansas winter wheat.

Iridaceae é uma das maiores famílias de monocotiledôneas, apresentando cerca de 66 gêneros e 2.000 espécies. Sisyrinchium é o segundo maior gênero da família e o primeiro em número de espécies das Américas, com cerca de 140 espécies. Entretanto, apresenta problemas de delimitação de espécies e, muitas vezes, é de confusa identificação. O objetivo deste estudo é contribuir para a elucidação de problemas taxonômicos nas espécies de Sisyrinchium sec. Hydastylus sensu Ravenna, reconhecendo e caracterizando táxons ocorrentes na Região Sul do Brasil. Esse trabalho apresenta uma revisão bibliográfica das espécies da seção Hydastylus, com pequenas descrições e desenhos que ajudam na identificação das espécies de Sisyrinchium pertencentes a essa seção; caracteres de anatomia foliar que possam auxiliar na delimitação dessas espécies; e a descrição de duas espécies novas de Sisyrinchium ocorrentes na Região Sul do Brasil: Sisyrinchium antemeridianum Aita & L.Eggers e Sisyrinchium flabellatum Aita & L.Eggers. / Iridaceae is one of the largest families of monocots, with about 66 genera and 2,000 species. Sisyrinchium is the second largest genus in the family and the one with the most number of species in the Americas, with about 140 species. However, it presents problems with species delimitation and it is often of confusing identification. The aim of this study is to contribute to the elucidation of taxonomic problems in species of Sisyrinchium sec. Hydastylus sensu Ravenna, recognizing and characterizing taxa occurring in Southern Brazil. This work presents a bibliographic review of the species of section Hydastylus, with short descriptions and drawings that help to identify the species of Sisyrinchium belonging to this section; characters of leaf anatomy that can help the species delimitation, and the description of two new species of Sisyrinchium occurring in Southern Brazil: Sisyrinchium antemeridianum Aita & L.Eggers and Sisyrinchium flabellatum Aita & L.Eggers.

A maioria das plantas consegue defender-se contra infecções fúngicas por meios naturais, que podem ser induzidos por uma série de elicitores bióticos ou abióticos. O silício (Si) solúvel tem mostrado que é capaz de induzir resistência em várias espécies de plantas contra inúmeros patógenos. Neste trabalho foi proposta a avaliação dos compostos contento Si na redução dos sintomas da ferrugem causada pelo fungo biotrófico Hemileia vastatrix em plantas de cafeeiros suscetíveis bem como avaliar os parâmetros bioquímicos envolvidos nos processos de resistência. Primeiramente, foram estudadas duas fontes de Si (silicato de Ca/Mg e silicato de potássio) em cinco doses para padronizar uma dose/fonte para os experimentos futuros. Foi possível observar que as plantas de cafeeiros não tiveram diferença significativa nos parâmetros de desenvolvimento como altura das plantas, área foliar, número de folhas para nenhuma das fontes e doses analisadas. Porém quando se tratava da contagem do número de lesões por cm2, a fonte silicato de potássio na dose de 5mM conseguiu suprimir em até 60% o desenvolvimento das lesões causadas pelo fungo. Com a fonte e dose estabelecidas, o segundo passo do trabalho foi avaliar quais os processos bioquímicos envolvidos na resistência conferida pelo Si em plantas de cafeeiro. Foram analisadas as atividades das enzimas relacionadas ao estresse oxidativo (peroxidases guaiacol e ascorbato, catalases, e superóxido desmutases) e relacionadas à defesa (glucanase, quitinase e PAL). As folhas foram coletadas para a obtenção do extrato protéico em diferentes intervalos de tempo após a inoculação com o fungo: as 24, 48, 72 e 96 horas após a inoculação e como controle foi utilizado o tempo zero (sem inoculação). Nesta fase foi possível observar que a atividade das enzimas CAT, SOD, APX foi maior em plantas tratadas indicando que o Si parece estimular uma resposta mais rápida ao estresse oxidativo. O mesmo ocorreu com as enzimas relacionadas à defesa. A partir destes resultados podemos afirmar que o Si estimula uma resposta de defesa mais rápida em plantas de café suscetíveis à ferrugem quando inoculadas com o fungo patogênico / Most plants can defend themselves against fungal infections by natural means, which can be induced by a number of biotic and abiotic elicitors. Soluble silicon (Si) has been shown to induce resistance in a number of plant species against several pathogens. The objective of this work was to assess the influence of silicon application of symptoms caused by the biotrophic fungus Hemileia vastatrix in susceptible coffee plants and evaluate the biochemistry process involved in defense mechanism. First of all, were studied two Si sources (Ca/Mg silicate and potassium silicate) in five doses to standardize dose/source for the future experiments. The statistical analysis showed that no difference was observed in relation to plant height, leaf area and number of leaves. However, the number of lesions reduced 60% in the higher silicon dose when compared to the number of lesions in control plants. Infected plants were found to have a linear decrease of lesions with the increase of silicate concentration. The lowest number of lesions per leaf area was observed in plants that received 5 M of Si from potassium silicate. This result indicates the use of silicon as an alternative for an ecological management system for coffee disease protection. The second step of this work was to evaluate the biochemistry process involved in resistance induced by Si in susceptible coffee plants. The activity of the enzymes related to oxidative stress (peroxidases, catalase, and superoxide desmutase) and related to defense (glucanase, chitinase, PAL) was evaluated. The leaves were collected in different time intervals after the fungus inoculation (24, 48, 72 e 96 hours after the fungus inoculation) in order to obtain the protein extract. It was possible to observe that the activity of CAT, SOD and APX was higher in Si-treated coffee plants suggesting that Si could stimulate a faster response to oxidative stress. The same situation occurred to the defense related enzymes. By the results obtained here it is possible to verify that Si can stimulate a faster defense response in susceptible coffee plants when inoculated with coffee leaf rust fungus