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Mapping of drought tolerance and leaf rust resistance in wheatSmith, Lauren M. January 1900 (has links)
Master of Science / Department of Agronomy / John P. Fellers / Allan K. Fritz / Water availability is commonly the most limiting factor to crop production, especially in drought prone areas like the Midwest. This study was conducted to map quantitative trait loci (QTL) involved in drought tolerance in wheat (Triticum aestivum L.) to enable their use for marker assisted selection (MAS) in breeding. A population of 122 F[subscript]7 derived recombinant inbred lines from a cross between Dharwar Dry and Sitta, spring wheat lines with contrasting drought tolerances, was analyzed using the amplified fragment length polymorphism (AFLP) technique and Diversity Array Technology (DArT) markers to create a QTL map. Of the 256 AFLP primer combinations evaluated, 151 were found to be polymorphic between the parents and were used to screen the population. A linkage map of 48 groups was created from the combined DArT markers, AFLP data, and SSR markers. This was used to create a QTL map which identified QTL in 24 of these groups. Using these markers for MAS in a breeding program could overcome the difficulties of selecting for drought tolerance.
Another serious limitation to wheat production is leaf rust caused by the pathogen Puccinia triticina. Leaf rust causes between 1% and 20% yield loss on average and tends to be the worst in years with high yield potential. PI 289824 contains a single, dominant gene for seedling resistance mapping to chromosome 5BS and thought to be different from Lr52. An F[subscript]2 mapping population from a cross between PI 289824 and Jagger was used to try to identify markers very closely linked to the gene and therefore useful for MAS. The population presented some mapping challenges, but with the use of SSR and EST-STS markers, the gene was flanked. However, the markers were at too a great distance to be useful for mapping.
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Mycosphaerella species causing leaf blotch on Eucalyptus species in South AfricaHunter, Gavin Craig 21 November 2011 (has links)
Studies presented in this thesis, highlight the complexity and importance of Mycosphaerella leaf disease (MLD) on Eucalyptus spp., especially in South Africa. In Chapter I, a review of the literature dealing with Mycosphaerella and MLD of Eucalyptus spp. is presented. It is clear from this review that the disease is prevalent in most countries where Eucalyptus spp. are commercially grown, including Australia where they are native. The number of Mycosphaerella species known from Eucalyptus spp. is increasing and this suggests that their economic effect on commercial Eucalyptus forestry, will probably Increase. It will thus become important to effectively identifY species responsible for MLD. To do this, the existing complex taxonomy of this group of fungi, will undoubtedly prove to be an obstacle. However, DNA based identification methods are proving useful in identifying species and delimiting lineages within Mycosphaerella. Future commercial propagation of Eucalyptus spp. will need to seriously consider the use of hybrids resistant to infection by Mycosphaerella spp. Furthermore, there will be a serious need for effective quarantine measures to prevent the introduction of new, perhaps more pathogenic, Mycosphaerella spp. into areas where they do not already occur. Three species of Mycosphaerella, M. molleriana, M. M. nubilosa and M. juvenis have traditionally been regarded as the most important Mycosphaerella spp. in South Africa. At various times, each species has been considered to be the only pathogen causing MLD in the country. Results from Chapter 2 and Chapter 3 have shown that M. nubilosa is the main pathogen responsible for MLD, especially, on E. nitens in the KwaZulu-Natal province of South Africa. This is interesting as M. molleriana, which was originally thought to be the only species in South Africa, was not isolated. Moreover, the susceptibility of E. nitens to M. nubilosa appears to be high, resulting in severe defoliation. Considering that E. nitens is a popular species grown at higher altitudes of South Africa, the recognition of M. nubilosa is important. This fungus is well recognized in Australia as an important pathogen and comparisons of data from that country will be useful in the future. Several Mycosphaerella spp. have, in the past been found to occur within single stands of commercial Eucalyptus spp. As part of the research presented in Chapter 3, surveys conducted in South Africa showed that there are seven species of Mycosphaerella occurring in plantations. These include: M. ellipsoidea, M. irregulariramosa, M. juvenis, M. lateralis, M. marksii, M. nubilosa and one newly described species M. fori. All of these species, apart from M. fori, were previously known to occur in South Africa. It is interesting that M. juvenis, previously thought to be one of the main species causing MLD, was found only to occur in a low numbers. This suggests that species causing epidemics may change over time. The identification of M. fori from a previously well surveyed area was unexpected. This new species was dominant in Tzaneen and future surveys will be conducted to determine its distribution and host range within South Afiica. The identification of a new species also highlights the need for additional surveys in South Africa to identify new species and to recognize possible new introductions of exotic Mycosphaerella spp. The presence of M. ellipsoidea, M. irregulariramosa, M. lateralis and M. marksii in this survey was not unusual, as they were previously known in South Africa. However, they were found only to occur at low levels and, as such, do not seem to contribute significantly to outbreaks of MLD.Various taxonomic and DNA-based methods have been used for the identification of Mycosphaerella spp. However, some taxonomic characters are of little value at the species level. In Chapter 4, RFLP's were considered as an option to differentiate between species of Mycosphaerella on Eucalyptus. Results of this study showed that the restriction enzyme HaeIII may be used for RFLP identification of Mycosphaerella spp. From a total of twenty-one Mycosphaerella spp. tested, RFLP digestion with HaeIII could resolve six of these species to species level. However, other species formed groups that had similar restriction profiles. They could be further separated based on ascospore germination patterns. This study forms a foundation for future studies in which other enzymes may be used together with HaeIIi to elucidate groups of species. It is suggested though, that this technique be combined with existing methods such as ascospore germination patterns and anamorph associations to identify species of Mycosphaerella occurring on Eucalyptus spp. with confidence. This should negate the use of expensive sequencing techniques, which are currently necessary. In virtually every country where Eucalyptus is grown commercially, MLD is prevalent. However, the specific Mycosphaerella spp. in countries are generally not the same. In Chapter 5, I used DNA sequence data from the ITS region of the rDNA operon as well as morphological data to identify M. heimii from Brazil and Hawaii, U.S.A. This represents the first report of the species from these countries. M heimii was previously thought to occur only in Madagascar and Indonesia, where it is recognized as a primary pathogen of several Eucalyptus spp, including E. urophylla. This is one of the main Eucalyptusspp. in Brazil. It has thus been suggested that this species may have been introduced into these countries via infected seed lots. This highlights the need for effective quarantine measures within these and other South American countries to inhibit the further spread of this pathogen through South America. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Microbiology and Plant Pathology / Unrestricted
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Engineered Disease Resistance in Cotton Using RNA-Interference to Knock down Cotton leaf curl Kokhran virus-Burewala and Cotton leaf curl Multan betasatellite ExpressionAhmad, Aftab, Zia-Ur-Rehman, Muhammad, Hameed, Usman, Qayyum Rao, Abdul, Ahad, Ammara, Yasmeen, Aneela, Akram, Faheem, Bajwa, Kamran, Scheffler, Jodi, Nasir, Idrees, Shahid, Ahmad, Iqbal, Muhammad, Husnain, Tayyab, Haider, Muhammad, Brown, Judith 14 September 2017 (has links)
Cotton leaf curl virus disease (CLCuD) is caused by a suite of whitefly-transmitted begomovirus species and strains, resulting in extensive losses annually in India and Pakistan. RNA-interference (RNAi) is a proven technology used for knockdown of gene expression in higher organisms and viruses. In this study, a small interfering RNA (siRNA) construct was designed to target the AC1 gene of Cotton leaf curl Kokhran virus-Burewala (CLCuKoV-Bu) and the beta C1 gene and satellite conserved region of the Cotton leaf curl Multan betasatellite (CLCuMB). The AC1 gene and CLCuMB coding and non-coding regions function in replication initiation and suppression of the plant host defense pathway, respectively. The construct, V b, was transformed into cotton plants using the Agrobacterium-mediated embryo shoot apex cut method. Results from fluorescence in situ hybridization and karyotyping assays indicated that six of the 11 T-1 plants harbored a single copy of the V beta transgene. Transgenic cotton plants and non-transgenic (susceptible) test plants included as the positive control were challenge-inoculated using the viruliferous whitefly vector to transmit the CLCuKoV-Bu/ CLCuMB complex. Among the test plants, plant V beta-6 was asymptomatic, had the lowest amount of detectable virus, and harbored a single copy of the transgene on chromosome six. Absence of characteristic leaf curl symptom development in transgenic V beta-6 cotton plants, and significantly reduced begomoviral-betasatellite accumulation based on real-time polymerase chain reaction, indicated the successful knockdown of CLCuKoV-Bu and CLCuMB expression, resulting in leaf curl resistant plants.
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Quantifying Vein Patterns in Growing LeavesAssaf, Rebecca January 2011 (has links)
How patterns arise from an apparently uniform group of cells is one of the classical problems in developmental biology. The mechanism is complicated by the fact that patterning occurs on a growing medium. Therefore, changes in an organism’s size and shape affect the patterning processes. In turn, patterning itself may affect growth. This interaction between growth and patterning leads to the generation of complex shapes and structures from simpler ones. Studying such interactions requires the possibility to monitor both processes in vivo. To this end, we developed a new technique to monitor and quantify vein patterning in a growing leaf over time using the leaves of Arabidopsis thaliana as a model system. We used a transgenic line with fluorescent markers associated with the venation. Individual leaves are followed in many samples in vivo through time-lapse imaging. Custom-made software allowed us to extract the leaf surface and vein pattern from images of each leaf at each time point. Then average spatial maps from multiple samples that were generated revealed spatio-temporal gradients. Our quantitative description of wild type vein patterns during leaf development revealed that there is no constant size at which a part of tissue enclosed by vasculature will become irrigated by a new vein. Instead, it seemed that vein formation depends on the growth rate of the tissue. This is the first time that vein patterning in growing leaves was quantified. The techniques developed will later be used to explore the interaction between growth and patterning through a variety of approaches, including mutant analysis, pharmacological treatments and variation of environmental conditions.
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Characterization of Brillouin Scattering Spectrum in LEAF FiberLiu, Xuan January 2011 (has links)
Fiber optic sensors are designed to measure various parameters. The distributed fiber optics sensor has been a very promising candidate for the structural health monitoring. In this thesis, we characterized LEAF (Large Effective Area Fiber) fiber’s Brillouin scattering spectrum and investigated its potentiality for the distributed Brillouin temperature and strain sensor.
Optical fibers with complex refractive index profiles are applied to improve the Brillouin threshold by varying the Brillouin linewidth. As LEAF fiber has a modified refractive index profile, we investigated its Brillouin linewidth’s dependence on the square of the pump light’s frequency. We verified the Brillouin frequency’s variation with input SOP experimentally for LEAF fiber in the spontaneous regime. This sets a limitation for the frequency resolution of distributed Brillouin sensors. We also realized a simultaneous temperature and strain sensor with LEAF fiber applying the Brillouin optical time domain analysis. Based on the direct detection of LEAF beat frequencies, a simultaneous strain and temperature sensor was demonstrated.
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Chemical and biological characterization of antibacterial compounds present in Ochna pretoriensis (Ochnaceae) leaf extractsMakhafola, Tshepiso Jan 10 August 2010 (has links)
In preliminary work done in a tree leaf screening project in the Phytomedicine Programme (www.up.ac.za/phyto) Ochna pretoriensis acetone leaf extracts had good antibacterial activity against several important bacterial pathogens. The main aim of this study was to isolate and characterize antibacterial compounds present in the acetone leaf extract of Ochna species growing in South Africa. In a preliminary screening, the minimum inhibitory concentration of acetone leaf extracts of Ochna natalitia, Ochna pretoriensis, Ochna pulchra, Ochna gamostigmata, and Ochna. Serullata, against Staphylococcus aureus, Escherichia coli, Enterococcus faecalisand Pseudomonas aeruginosa were determined by using a serial microplate dilution assay. The number of antibacterial compounds in the extracts was also determined by bioautography against the same bacteria. The MIC values of the five species ranged from 0.039 mg/ml to 1.25 mg/ml. The lowest average MIC values observed were for O. Pretoriensis especially against E. Faecalis and E. Coli. The most sensitive organism to all the plants was E. coli. O. Pretoriensis had the lowest average MIC value and the highest total activity value of 1538 ml/g. Based on bioautography some of the Ochna species had antibacterial compounds with similar Rf values. The thin layer chromatography chemical profiles of the five plant extracts may be useful in the taxonomy of the genus. O. Pretoriensis was chosen for fractionation and isolation of antibacterial compound because it has the lowest average MIC values and highest total activity especially against E. Faecalis and E. coli. The acetone extract of O. Pretoriensis was fractionated into seven fractions (hexane, carbon tetrachloride, chloroform, ethyl acetate, 35% water in methanol, 70% water in methanol and butanol) by solvent-solvent fractionation. Only three of the seven fractions (carbon tetrachloride, chloroform, ethyl acetate fractions) had clearly defined antibacterial spots/lines on bioautograms. The three fractions were further fractionated using column chromatography from which three compounds were successfully isolated. The chemical structures of the isolated compounds were determined using NMR spectroscopy as β-Sitosterol (SS), ochnaflavone (OF) and ochnaflavone 7-O- methyl ether (OFME). Compounds that are related to sitosterol have activity against neurodegenerative disorders as well as estrogenic, analgesic, anti-inflammatory, anthelminthic and antimutagenic activity. OF and OFME are biflavonoids which belong to the group ochnaflavones previously characterized from Ochna obtusata. These compounds have anti-atherosclerotic, anti-inflammatory, and anti-tumor activity. They also inhibit lymphocytes proliferation, archidonic acid release and phospholipase activity. Moreover, OFME was reported to inhibit HIV-1 activity as well as HIV-1 reverse transcriptase activity. The antibacterial activity, and potential cytotoxic, genotoxic and antigenotoxic effects of the isolated compounds were determined. The MIC values ranged from 31.3 to 250 μg/ml. SS was more active against P. Aeruginosa with an MIC of 62.5 μg/ml, OF against P. Aeruginosa and E. Faecalis with MICs of 0.03 mg/ml and OFME against P. Aeruginosa with an MIC of 31.3 μg/ml. The isolated compounds were much less active than the positive control gentamycin. The compounds had low cytotoxic activity, with LC50 values of 193.8 μg/ml for β-Sitosterol, 125.9 μg/ml for OF and 125.9 μg/ml for OFME against Vero cells. The therapeutic indexes of the crude extract and the isolated compounds varied between 0.77 and 3.27, which is an indication of non-specific antibacterial activity i.e. general toxicity, thus the crude plant extract and compounds isolated from O. Pretoriensis can only be recommended for external applications. e.g. topical treatments. None of the compounds tested had potential genotoxic and/or antigenotoxic effects. The number of revertants in the mutagenicity experiments was less than twice the number of revertants in the negative control. The percentage inhibition of 4NQO in the antimutagenicity experiments were less than 45%. The results obtained in this case may be principally associated with the general toxicity of the test samples to the bacteria used in this study. Comparison of the total activity of the crude extract and the fractions gave a clear indication of synergic interaction of compounds in the crude extract to successfully inhibit the growth of the test pathogens. Approximately 76% of activity was lost in the 34% of dry mass lost during fractionation. Twelve percent of activity was present in the chloroform fraction and 6% in the carbon tetrachloride fraction. Despite the evidence for synergistic activity, the crude extract was also relatively toxic to the Vero cells with a therapeutic index of 0.8. As far as could be established, the antibacterial activity of members of the Ochna genus and the cytotoxicity of ochnaflavones were determined for the first time in the current study. The two most active antibacterial compounds (ochnaflavone and ochnaflavone 7-O- methyl ether) are being reported from this species for the first time. The relative safety of the crude extract and the compounds isolated from this plant was relatively low. Preparations of O. Pretoriensis may be safe in a topical application but internal use cannot be recommended for treating antibacterial infections before animal toxicity studies have been carried out. Caution is also required in using the isolated compounds or crude extracts for other applications. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Paraclinical Sciences / unrestricted
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A perda de área foliar e sua relação com o gênero Ectatomma (Formicidae: Ectatomminae) em uma comunidade de cerrado / The loss of leaf and its relation to genus Ectatomma (Formicidae:Ecatomminae) in a cerrado communityErdogmus, Graziella Diogenes Vieira Marques 01 March 2010 (has links)
A perda de área foliar, em sua maior parte resultante da ação de herbívoros, é um dos fatores que regulam o sucesso reprodutivo de uma planta e indiretamente de todos os consumidores relacionados na comunidade. A maior parte dos estudos feitos com perda foliar e herbivoria são pontuais, ou seja, referem-se a uma ou poucas espécies vegetais. Para os cerrados, a savana tropical brasileira, a maior savana em extensão e diversidade no mundo, não há nenhum estudo que investigue a dinâmica de perda de área foliar ao longo do tempo na comunidade, considerando os fatores climáticos e fenológicos que podem influenciar este processo, além da presença dos principais predadores de herbívoros atrópodes na vegetação de cerrado, as formigas, sendo este o principal objetivo do presente estudo. O estudo foi desenvolvido em uma área de reserva de Cerrado de 628 ha, situada em Uberlândia, MG (18º59S, 48º18O), tendo os dados sido coletados de janeiro a dezembro de 2007 (bimestralmente) e de 2008 (mensalmente). Foram estabelecidos aleatoriamente na área de cerrado sensu stricto da reserva, 15 quadrantes de 10m x 10m onde todos os indivíduos com diâmetro à altura do peito igual ou superior a três centímetros foram marcados e incluídos na amostra. Em cada quadrante observou-se (sem remoção), seis folhas (escolhidas aleatoriamente duas da parte alta, duas da parte mediana e duas de ramos mais baixos), por planta de cada espécie, sendo registrada a porcentagem de área foliar perdida. Foram amostrados um total de 1006 indivíduos distribuídos em 82 espécies e 34 famílias. A espécie Ouratea spectabilis (137 indivíduos) foi a mais abundante na área de estudo, seguida de Banisteriopsis malifolia (122), Machaerium acutifolium (59) e Tabebuia ochracea (41). A perda de área foliar variou significativamente ao longo do tempo (meses) e entre as famílias e espécies de plantas. Os meses mais secos do ano apresentaram a maior perda de área foliar tanto em 2007 (abril, junho e agosto) quanto em 2008 (de maio a agosto). Os fatores climáticos influenciaram significativamente a perda de área foliar, pois ela variou ao longo do tempo. Portanto, os resultados do presente estudo indicaram que a perda de área foliar da comunidade de plantas de cerrado varia sazonalmente e ocorre com maior intensidade na estação seca. Fatores abióticos como temperatura e precipitação influenciam a fenologia das espécies de plantas, que buscam o melhor momento para maximizar seu desenvolvimento e evitar que inimigos naturais causem perdas significativas para sua sobrevivência e sucesso reprodutivo. As características de cada espécie promovem diferenças na perda de área foliar, devido às defesas e/ou associações mutualísticas que possuem. A presença de nectários extraflorais associados às formigas desempenha um papel significativo para as plantas. Dentre os fatores bióticos, a presença de ninhos de formigas Ectatomma teve um impacto positivo para as plantas reduzindo a perda de área foliar. / The loss of leaf area, mostly resulting from the action of herbivores is one of the factors that regulate the reproductive success of a plant and indirectly to all consumers connected to the community. Most studies of herbivory and leaf loss are punctual, i.e., refer to one or a few plant species. In the cerrado, a tropical savanna in Brazil, the largest savanna in scope and diversity in the world, there are no studies to investigate the dynamics of loss of leaf area over time in the community, considering the climatic factors, phenology and carnivorous ants that can influence this process, which is the main objective of this study. The study was conducted in a closed area of 628 ha of Cerrado, located in Uberlandia, Brazil (18 º 59\'S, 48 18\'W) and the data were collected from January to December 2007 (bimonthly) and 2008 (monthly). Were established randomly in the area of cerrado of the reserve, 15 quarters of 10m x 10m where all trees with diameter at breast height greater than or equal to three centimeters were marked with numbered label and sampled. In each quadrant was observed (without removal), six leaves (randomly chosen two of high part, two of the middle, and two of the lower branches), in plant species, and recorded the percentage of leaf area lost. We sampled a total of 1006 individuals belonging to 82 species and 34 families. The species Ouratea spectabilis (137 individuals) was the most abundant in the study area, followed by Banisteriopsis malifolia (122), Machaerium acutifolium (59) and Tabebuia ochracea (41). The loss of leaf area varied significantly over time (months) and between families and species of plants. The driest months of the year showed the greatest loss of leaf area in both 2007 (April, June and August) and in 2008 (May-August). Climatic factors also significantly influenced the loss of leaf area, as it varied over time, depending on the rainfall and temperature variation. Therefore, the results of this study indicated that the loss of leaf area community of cerrado plants varies seasonally and occurs mostly in the dry season. Abiotic factors like temperature and rainfall influence the phenology of species of plants, seeking the best time to maximize their development and prevent natural enemies result in significant losses for their survival and reproductive success. The characteristics of each species promote differences in leaf area loss due to defenses and / or mutualistic associations they have. The presence of extrafloral nectaries associated with ants play a significant role for plants. For this reason, among the biotic factors, the presence of Ectatomma nests had a significant positive impact on reducing the loss of leaf area, since these ants are predators of herbivores.
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Arctic Environmental Change across the Pliocene-Pleistocene TransitionKeisling, Benjamin Andrew 17 July 2015 (has links)
Environmental change in the Arctic proceeds at an unprecedented rate. The Pliocene epoch (5-2.65 million years ago) represents an analog for future climate conditions, with pCO2 and continental configurations similar to present. Yet conditions in the Pliocene Arctic are poorly characterized because of sparse sampling. The records that do exist indicate periods of extreme warmth, as well as the first expansion of large ice-sheets in the Northern Hemisphere, took place from the end of the Pliocene into the early Pleistocene. Understanding these deposits and their implications for our future requires developing a sense of climatic evolution across the Plio-Pleistocene transition and especially during the intensification of Northern Hemisphere Glaciation (iNHG) ~2.7 million years ago. Here we reconstruct environmental change in the Arctic using a suite of organic geochemical proxies in a sedimentary archive recovered from Lake El'gygytgyn, Arctic Northeast Russia. We use the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) and the hydrogen isotopic composition (δD) of plant leaf-waxes (n-alkanes) to reconstruct relative temperature change across the interval spanning 2.8 to 2.4 million years ago. Our work demonstrates that, following the first major glaciation of the Northern Hemisphere, it took multiple glacial cycles for the Arctic to become synchronized with the climatic changes recorded in the deep ocean. This work has implications for understanding the role of sea-level, sea-ice, vegetation and carbon-cycle feedbacks in a changing Arctic.
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Konstrukční návrh nesymetrické parabolické pružiny / Design of Asymmetrical Parabolic SpringŽák, Ondřej January 2018 (has links)
This thesis is focused on design of parabolic spring for a truck. Characteristics of the spring are designed with respect to loads during heavy braking. Thesis contains a brief summary of current truck suspension, the spring design and suggestion for testing methodology for longitudinal load.
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Cellular events and regulations during leaf margin morphogenesis in Arabidopsis thaliana / Événements cellulaires et régulations au cours de la morphogenèse foliaire chez Arabidopsis thalianaSerra, Léo 25 April 2019 (has links)
Comprendre comment la coordination des cellules entre elles permet l’émergence d’une forme est une des questions les plus fascinantes en biologie du développement. Au cours de cette thèse, nous avons utilisé les premiers stades de développement des feuilles dentelées d'Arabidopsis thaliana comme modèle pour étudier la relation entre les évènements cellulaires et la morphogenèse. Pendant le développement des feuilles d'Arabidopsis thaliana, le contrôle fin de la prolifération et de l'expansion cellulaire permet la croissance différentielle au niveau de la marge foliaire, nécessaire à la formation des indentations. Dans ce modèle, la croissance différentielle est le résultat de l'interaction entre la signalisation de l’auxine et l’activité des facteurs de transcription CUP SHAPED COTYLEDONS impliqués dans le maintien de l'identité des domaines frontières. Pour affiner la compréhension des relations complexes entre les facteurs de transcriptions CUC, les réponses auxiniques et les événements cellulaires à l'origine des indentations foliaires, nous avons utilisé des expériences d’imagerie en temps réel sur des primordia foliaires de lignées exprimant des rapporteurs de développement et/ou de réponse auxinique. Nos résultats ont révélé un contrôle dynamique de la croissance différentielle à la marge des feuilles et l'implication critique de CUC3 dans la répression locale de la croissance cellulaire. / How a shape arises from the coordinated behavior of cells is one of the most fascinating questions in developmental biology. Here we used the early stages of development of serrated leaves in Arabidopsis thaliana as a model to study the tight relation between cellular behaviour and morphogenesis. During Arabidopsis thaliana leaf development the fine control of cell proliferation and cell expansion sustains differential growth at the margin required for the formation of leaf outgrowth named teeth. In this model, differential growth is the result of interplay between auxin signaling and CUC transcription factors that are involved in the maintenance of boundary domain identity. To clarify the interconnected relations between patterns of CUC TFs and auxin responses as well as the cellular events behind serrations we used time-lapse experiments on vegetative primordia of lines expressing developmental and/or auxin response reporters. Our results revealed a tight and dynamic control of differential growth at the leaf margin and the critical involvement of CUC3 in the local repression of cell growth in combination with low auxin responses.
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