Made available in DSpace on 2014-06-11T19:35:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-18Bitstream added on 2014-06-13T21:06:58Z : No. of bitstreams: 1 cruz_jcs_dr_botfca.pdf: 308912 bytes, checksum: 39a12254aaeafdcfc7adbf88eea87463 (MD5) / A doença conhecida por hérnia das crucíferas é causada pelo patógeno Plasmodiophora brassicae Woronin, sendo uma das mais importantes e de difícil controle em brássicas. Em virtude da dificuldade de preservação das estruturas de resistência de P. brassicae em condições laboratoriais, por se tratar de um parasita obrigatório, foi desenvolvido um ensaio visando a obtenção de uma técnica eficiente e prática de preservação. Para isto, raízes de diferentes brássicas naturalmente infectadas por P. brassicae, contendo hérnias, foram coletadas de uma mesma propriedade (município de Pardinho - SP), em diferentes períodos, e imediatamente congeladas em freezer a -20°C±2°C. Os tratamentos foram: T1: hérnias congeladas por 389 dias, (rúcula); T2: hérnias congeladas por 242 dias (brócolis); T3: hérnias congeladas por 21 dias (couve-chinesa) e T4: testemunha (sem inóculo). Os testes de patogenicidade, após os diferentes períodos de armazenamento, foram realizados em condições controladas de casa de vegetação (25±2°C), onde em cada planta, de uma variedade suscetível de couve-chinesa (Pak choi), foi inoculado 2mL da suspensão de esporos, dos diferentes tratamentos, na concentração de 107 esporos.mL–1. Cada tratamento contou com seis repetições distribuídas ao acaso. Passadas cinco semanas, após a inoculação, as raízes foram lavadas e avaliadas. Houve diferença estatística significativa entre os materiais avaliados quanto aos diferentes períodos de armazenamento em “freezer”. Os materiais congelados entre 21 a 242 dias preservaram suas características infectivas, sendo este método uma boa opção para a preservação das estruturas de repouso nesse período. Foram realizados testes de patogenicidade e análises moleculares de populações de P. brassicae,... / Disease known as clubroot of crucifers is caused by the pathogen Plasmodiophora brassicae Woronin, and is one of the most important and difficult control crucifer diseases in brassicas. Because of the difficulty in preserving the resistance structures of P. brassicae under laboratory conditions, given that it is an obligate parasite, an assay was carried out to develop a practical and effective technique that would allow further studies to be conducted. On this proposal, roots of different brassica species naturally infected by P. brassicae showing clubroot symptoms were collected in the some grower (Pardinho, SP-city, Brazil) during different seasons, and were immediately frozen at approximately 20°C±2°C. The treatments were: T1: clubroots frozen for 389 days (arugula); T2: clubroots frozen for 242 days (broccoli); T3: clubroots frozen for 21 days (Chinese cabbage), and T4: control (no inoculum). The pathogenicity tests after different storage periods were conducted under controlled greenhouse conditions (25±2°C); each plant of a susceptible variety of Chinese cabbage was inoculated with 2mL of a spore suspension of the various treatments at a concentration of 107spores.mL-1. Each treatment consisted of six replicates distributed at random. The roots were washed and evaluated five weeks after inoculation. There were statistical differences between the materials evaluated with respect to different storage periods in the freezer. Materials kept frozen between 21 and 242 days retained their infective traits. Therefore, this method is a good option to preserve resting spores during this period. In addition, pathogenicity tests and molecular analyses were conducted with P. brassicae populations obtained from infected roots of several production regions of Brazil, on some...(Complete abstract click electronic access below)

Orientador: Edson Luiz Furtado / Banca: Marli Teixeira de Almeida Minhoni / Banca: Romulo Fujito Kobori / Banca: Louise Larissa May de Mio / Banca: César Júnior Bueno / Resumo: A doença conhecida por hérnia das crucíferas é causada pelo patógeno Plasmodiophora brassicae Woronin, sendo uma das mais importantes e de difícil controle em brássicas. Em virtude da dificuldade de preservação das estruturas de resistência de P. brassicae em condições laboratoriais, por se tratar de um parasita obrigatório, foi desenvolvido um ensaio visando a obtenção de uma técnica eficiente e prática de preservação. Para isto, raízes de diferentes brássicas naturalmente infectadas por P. brassicae, contendo hérnias, foram coletadas de uma mesma propriedade (município de Pardinho - SP), em diferentes períodos, e imediatamente congeladas em freezer a -20°C±2°C. Os tratamentos foram: T1: hérnias congeladas por 389 dias, (rúcula); T2: hérnias congeladas por 242 dias (brócolis); T3: hérnias congeladas por 21 dias (couve-chinesa) e T4: testemunha (sem inóculo). Os testes de patogenicidade, após os diferentes períodos de armazenamento, foram realizados em condições controladas de casa de vegetação (25±2°C), onde em cada planta, de uma variedade suscetível de couve-chinesa (Pak choi), foi inoculado 2mL da suspensão de esporos, dos diferentes tratamentos, na concentração de 107 esporos.mL-1. Cada tratamento contou com seis repetições distribuídas ao acaso. Passadas cinco semanas, após a inoculação, as raízes foram lavadas e avaliadas. Houve diferença estatística significativa entre os materiais avaliados quanto aos diferentes períodos de armazenamento em "freezer". Os materiais congelados entre 21 a 242 dias preservaram suas características infectivas, sendo este método uma boa opção para a preservação das estruturas de repouso nesse período. Foram realizados testes de patogenicidade e análises moleculares de populações de P. brassicae, ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Disease known as clubroot of crucifers is caused by the pathogen Plasmodiophora brassicae Woronin, and is one of the most important and difficult control crucifer diseases in brassicas. Because of the difficulty in preserving the resistance structures of P. brassicae under laboratory conditions, given that it is an obligate parasite, an assay was carried out to develop a practical and effective technique that would allow further studies to be conducted. On this proposal, roots of different brassica species naturally infected by P. brassicae showing clubroot symptoms were collected in the some grower (Pardinho, SP-city, Brazil) during different seasons, and were immediately frozen at approximately 20°C±2°C. The treatments were: T1: clubroots frozen for 389 days (arugula); T2: clubroots frozen for 242 days (broccoli); T3: clubroots frozen for 21 days (Chinese cabbage), and T4: control (no inoculum). The pathogenicity tests after different storage periods were conducted under controlled greenhouse conditions (25±2°C); each plant of a susceptible variety of Chinese cabbage was inoculated with 2mL of a spore suspension of the various treatments at a concentration of 107spores.mL-1. Each treatment consisted of six replicates distributed at random. The roots were washed and evaluated five weeks after inoculation. There were statistical differences between the materials evaluated with respect to different storage periods in the freezer. Materials kept frozen between 21 and 242 days retained their infective traits. Therefore, this method is a good option to preserve resting spores during this period. In addition, pathogenicity tests and molecular analyses were conducted with P. brassicae populations obtained from infected roots of several production regions of Brazil, on some...(Complete abstract click electronic access below) / Doutor

Submitted by (edna.saturno@ufrpe.br) on 2016-11-23T13:41:55Z No. of bitstreams: 1 Andre Malacarne Milanez.pdf: 1324658 bytes, checksum: adee6c780c08c674412b2e646d09b54f (MD5) / Made available in DSpace on 2016-11-23T13:41:55Z (GMT). No. of bitstreams: 1 Andre Malacarne Milanez.pdf: 1324658 bytes, checksum: adee6c780c08c674412b2e646d09b54f (MD5) Previous issue date: 2009-02-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Trichoplusia ni (Hübner) (Lep.: Noctuidae) is a pest of great importance in horticulture, because of the use of wide range of hosts. The control of this pest is basically done with chemical insecticides. The use of egg parasitoids of the genus Trichogramma is an alternative for biological control of lepidopteran-pest. However, for the efficiency of these parasitoids are needed studies regarding selection of species and/or strains considering the environment and hosts. Thus, the performance of two strains of Trichogramma exiguum Pinto & Platner, six strains of Trichogramma pretiosum Riley, Trichogramma atopovirilia Oatman & Platner, Trichogramma acacioi Brun, Moraes & Soares, Trichogramma marandobai Brun, Moraes & Soares and Trichogramma demoraesi Nagaraja (Hym.: Trichogrammatidae) parasitizing eggs of T. ni were studied. The biological parameters evaluated were: percentage of parasitism and viability, sex ratio and number of individuals emerging per egg of the host. T. pretiosum strain (Tpsd) obtained the best performance in the parameters of the percentage of parasitism and viability. Based on these results, the influence of the host densities and age of the host was investigated for T.pretiosum strain (Tspd) at 20, 25 and 30 ºC. The proportion of eggs of T. ni offered, at the threetemperatures, influence number of eggs parasitized, percentage of parasitism and individuals emerged per egg. In addition, the best ratio of host egg per Trichogramma, regardless of temperature studied, was 15:1. Eggs up to 24 hours in any temperature allowed the best performance in the biological parameters measured, except in the number of individuals per egg. Thus, T. pretiosum exhibited better performance parasitizing eggs up to 24 hours of age and with host ratio of 15 eggs per female. / Trichoplusia ni (Hübner) (Lep.: Noctuidae) é uma praga de grande importância na olericultura, e seu controle é feito basicamente com produtos químicos. A utilização de parasitóides de ovos do gênero Trichogramma é uma alternativa no controle biológico de lepidópteros-praga. No entanto, para que haja eficiência no uso destes parasitóides são necessários à realização de estudos básicos visando à seleção de espécies e/ou linhagens em relação ao ambiente e seus hospedeiros. Desta forma, comparou-se o desempenho de duas linhagens de Trichogramma exiguum Pinto & Platner, seis linhagens de Trichogramma pretiosum Riley, Trichogramma atopovirilia Oatman & Platner, Trichogramma acacioi Brun, Moraes & Soares, Trichogramma marandobai Brun, Moraes & Soares e Trichogramma demoraesi Nagaraja (Hym.: Trichogrammatidae) parasitando ovos de T. ni. Os parâmetros biológicos avaliados foram: porcentagem de parasitismo e viabilidade; razão sexual e número de indivíduos por ovo. T. pretiosum linhagem (Tpsd) obteve o melhor desempenho nos parâmetros de porcentagem de parasitismo e viabilidade. Com base nesses resultados, estudos visando esclarecer a influência do número e idade dos ovos da praga sobre os parâmetros biológicos de T. pretiosum linhagem(Tspd) nas temperaturas de 20, 25 e 30 ºC foram realizados. A proporção de ovos de T. ni, nas três temperaturas, influênciou o número de ovos parasitados, a porcentagem de parasitismo e o número de individuo por ovos, sendo que a relação ideal de ovos da praga por Trichogramma, independente da temperatura estudada, é de 15:1. Ovos com até 24 horas, em qualquer temperatura, proporcionam os melhores desempenhos nos parâmetros biológicos avaliados. Desta forma, T. pretiosum tem melhor desempenho em ovos com até 24 horas de desenvolvimento embrionário e que esteje em proporção próximos a 15 ovos por fêmea.

Submitted by (edna.saturno@ufrpe.br) on 2016-12-01T11:35:30Z No. of bitstreams: 1 Vanessa Correa Santos.pdf: 426382 bytes, checksum: 7f2a707e64c6b920d1e709bfb3336891 (MD5) / Made available in DSpace on 2016-12-01T11:35:30Z (GMT). No. of bitstreams: 1 Vanessa Correa Santos.pdf: 426382 bytes, checksum: 7f2a707e64c6b920d1e709bfb3336891 (MD5) Previous issue date: 2010-02-01 / Plutella xylostella (L.) (Lepidoptera: Plutellidae), popularly known as diamondback moth, is a major pest of brassicaceae crops (e.g., kale, cauliflower, broccoli, and cabbage) throughout the world. Several insecticides have been intensively used during several cultivation cycles and, even in some areas, up to 15 to 20 applications per season have been observed. Besides the problems they may cause to human and environmental health, the frequent use of these products has been associated to the evolution of resistance in P. xylostella populations to various insecticides such as the pyrethroids, carbamates, organophosphates, and even Bacillus thuringiensis. The current study objective was to identify the resistance in P. xylostella populations from Pernambuco State, when exposed to abamectin, methomyl, lufenuron, indoxacarb, and diafentiuron. Concentration-response regressions were established using 2nd-instar larvae of P. xylostella. All P. xylostella populations showed significant resistance ratio (RR) to at least one insecticide. The smallestCL50s values were estimated for abamectin, which varied from 0.01 to 0.74 mg/L and the highest CL50s were estimated for diafentiuron, which varied from 47.9 to 122.2 mg/L. The Bezerro County population presented the highest resistance ratios to indoxacarb (25.3-fold), abamectin (61.7-fold), and lufenuron (705.2-fold), compared to the reference population. TheBonito and Jupi Counties populations were 33.0- and 12.0-times more resistant to lufenuron and abamectina, respectively. These results demonstrate that intensive and indiscriminate use of insecticides in Pernambuco must be a concern, which suggests the immediate establishment of a resistance management program associated to integrated pest management in these areas. / Plutella xylostella (L.) (Lepidoptera: Plutellidae), conhecida popularmente como traça-das-crucíferas é considerada a principal praga do cultivo de brássicas (ex: couve, couve-flor, brócolis e repolho) em todo o mundo. Diversos inseticidas têm sido utilizados intensivamente durante o ciclo da cultura, e em algumas áreas já foram detectadas 15 a 20 aplicações por ciclo. Além dos problemas gerados à saúde do agricultor e ao meio ambiente, o uso excessivo desses produtos tem proporcionado o aparecimento de populações resistentes deste inseto-praga a diversos compostos químicos, como é o caso dos inseticidas piretróides, carbamatos, organofosforados e Bacillus thuringiensis. O presente estudo teve como objetivo identificar a resistência em populações de P. xylostella do Estado de Pernambuco, utilizando os inseticidas abamectina, metomil, lufenurom, diafentiuron e indoxacarbe. Curvas de concentração-resposta foram estabelecidas usando lagartas de 2º instar de P. xylostella. Todas as populações pernambucanas de P. xylostella apresentaram razão de resistência (RR) significativa a pelomenos um inseticida. As menores CL50s foram registradas para o inseticida abamectina, variando de 0,01 a 0,74 mg/L e as maiores CL50s foram para o inseticida diafentiuron, 47,9 a 122,2 mg/L. A população do município de Bezerros apresentou as maiores razões de resistência 25,3 a indoxacarbe, 61,7 a abamectina e 705,2 a lufenurom, quando comparadas àpopulação suscetível. A população do município de Bonito apresentou uma razão de resistência 33,0 a lufenurom e Jupi 12,0 para abamectina. Estes resultados demonstram que o uso intensivo e indiscriminado de inseticidas na região Agreste de Pernambuco é preocupante, sugerindo o estabelecimento de um programa de manejo da resistência associado ao manejo integrado de pragas nesta área.

Genetic composition of hybrid zones often reflects geographical and ecological gradients. Hybrid zone of Arabidopsis lyrata and A. arenosa in Central Europe can be convenient model system for testing such hypothesis. These are well circumscribed but still interfertile, and their offspring is fully fertile. Besides repeated hybridisation events, the current state is complicated by the autopolyploidisation events of one of the parents, namely A. lyrata, which is present in the area studied both as diploid and tetraploid. This hybrid zone was already described in previous publications, which showed certain gradient of introgression. Moreover, the area of the hybrid zone represents a transition between Alpine and Pannonian climate along an altitudinal gradient leading from the Prealps to the lowland Wienerwald. The current thesis is the as yet most detailed study of this hybrid zone both in respect of number of studied populations and the amount of data acquired using the methods of RAD Sequencing, multivariate morphometrics and flow cytometry. The analysis of genetic data showed a gradient of introgression, where parental populations are placed at opposite ends, whereas genetically intermediate hybrids are placed in its centre. Analysis of the genome size showed an additional gradient, where hybrids...

Yes / Capsella bursa-pastoris (L.) Medik. is a species with a cosmopolitan distribution which shows considerable morphological variation. Numerous authors have recognised widely differing numbers of varieties, microspecies or other infraspecific subdivisions (segregates) of this species. In an attempt to clarify this situation, we grew British material of the species under controlled conditions through to the F) generation to remove environmental variation, and assessed the plants on the basis of a range of morphological criteria, namely leaf shape, capsule size and also length of time taken to flower. Analysis of these characteristics consistently produced four basic groups, which had been previously described. Herbarium specimens could also nearly always be assigned to one of these groups. Limited chromosome counts suggest that two of these groups are diploid and two are tetraploid. We suggest this fourfold division into broad groups reflects the major genetic separations within the species, but that there is also considerable phenotypic plasticity shown by C. bursapastoris in response to factors such as shade or trampling. These four groups appear to differ in their geographic.al distribution in Britain. KEYWORDS: Shepherd's Purse, morphological variation, leaf characters, capsule characters, chromosome

Yes / The coexistence of hermaphrodites and female-sterile individuals, or androdioecy, has been documented in only a handful of plants and animals. This study reports its existence in the plant species Cardamine amara (Brassicaceae), in which female-sterile individuals have shorter pistils than seed-producing hermaphrodites. Morphological analysis, in situ manual pollination, microsatellite genotyping and differential gene expression analysis using Arabidopsis microarrays were used to delimit variation between female-sterile individuals and hermaphrodites. Female sterility in C. amara appears to be caused by disrupted ovule development. It was associated with a 2.4- to 2.9-fold increase in clonal propagation. This made the pollen number of female-sterile genets more than double that of hermaphrodite genets, which fulfils a condition of co-existence predicted by simple androdioecy theories. When female-sterile individuals were observed in wild androdioecious populations, their ramet frequencies ranged from 5 to 54 %; however, their genet frequencies ranged from 11 to 29 %, which is consistent with the theoretically predicted upper limit of 50 %. The results suggest that a combination of sexual reproduction and increased asexual proliferation by female-sterile individuals probably explains the invasion and maintenance of female sterility in otherwise hermaphroditic populations. To our knowledge, this is the first report of the coexistence of female sterility and hermaphrodites in the Brassicaceae.

Yes / Rapid advances in short-read DNA sequencing technologies have revolutionized population genomic studies, but there are genomic regions where this technology reaches its limits. Limitations mostly arise due to the difficulties in assembly or alignment to genomic regions of high sequence divergence and high repeat content, which are typical characteristics for loci under strong long-term balancing selection. Studying genetic diversity at such loci therefore remains challenging. Here, we investigate the feasibility and error rates associated with targeted long-read sequencing of a locus under balancing selection. For this purpose, we generated bacterial artificial chromosomes (BACs) containing the Brassicaceae S-locus, a region under strong negative frequency-dependent selection which has previously proven difficult to assemble in its entirety using short reads. We sequence S-locus BACs with single-molecule long-read sequencing technology and conduct de novo assembly of these S-locus haplotypes. By comparing repeated assemblies resulting from independent long-read sequencing runs on the same BAC clone we do not detect any structural errors, suggesting that reliable assemblies are generated, but we estimate an indel error rate of 5.7×10−5. A similar error rate was estimated based on comparison of Illumina short-read sequences and BAC assemblies. Our results show that, until de novo assembly of multiple individuals using long-read sequencing becomes feasible, targeted long-read sequencing of loci under balancing selection is a viable option with low error rates for single nucleotide polymorphisms or structural variation. We further find that short-read sequencing is a valuable complement, allowing correction of the relatively high rate of indel errors that result from this approach. / This study was supported by a grant from the Swedish Research Council to T.S.

Les angiospermes (ou plantes à fleurs) regroupent environ 350 000 espèces ayant divergé il y a 150 à 200 millions d’années en deux familles botaniques principales, les monocotylédones (les orchidées, les palmiers, les bananiers, les joncs, les graminées...) et les eudicotylédones (les Brassicaceae, les Rosaceae, les légumineuses...) représentant respectivement 20% et 75% des plantes à fleurs. Les angiospermes font l’objet de nombreux travaux de recherche, en particulier en génomique depuis 2000 avec le séquençage du premier génome de plantes (Arabidopsis thaliana) qui a précédé le décryptage des génomes d’un nombre important d’autres espèces modèles et/ou d’intérêt agronomique (environ 100 aujourd’hui). L’accès croissant à la séquence des génomes de plantes a permis de mettre à jour une importante diversité structurale de leur génome, en termes de taille physique, de nombre de chromosomes, de nombre de gènes et de richesse en éléments transposables. Les forces évolutives ayant permis une telle diversité structurale des génomes au cours de l’évolution sont au cœur des travaux de cette thèse. La paléogénomique se propose d’étudier à travers la reconstruction de génomes ancestraux, comment ces espèces ont divergé à partir d’ancêtres communs et quels mécanismes ont contribué à une telle plasticité de structure génomique. Dans cet objectif, les travaux de cette thèse ont mis en œuvre des méthodes basées sur la génomique comparée permettant l’étude de l’évolution structurale des génomes via la reconstruction des génomes ancestraux fondateurs des espèces modernes. Ainsi, un génome ancestral des angiospermes a été reconstruit constitué de 5 chromosomes et porteur de 6707 gènes ordonnés sur ceux-ci, permettant d’intégrer dans un même modèle les monocotylédones et les eudicotylédones et élucider leur histoire évolutive, notamment pour les espèces d’intérêt agronomique majeur telles que les céréales, les rosids et les Brassicaceae. L’inférence de ces génomes ancestraux des plantes modernes a permis l’identification et l’étude de l’impact des évènements de polyploïdie (doublement génomique), ubiquitaires chez les plantes. Nous avons montré que les génomes tendent à revenir à une structure diploïde suite à un évènement de polyploïdie. Cette diploïdisation structurale se fait au niveau caryotypique (par le biais de réarrangements chromosomiques impliquant la perte des centromères et télomères ancestraux) mais aussi géniques (par le biais de pertes de gènes ancestraux en double copies). Il a été montré que cette perte se faisait préférentiellement sur un des sous-génomes post-polyploïdie, menant au phénomène de « dominance des sous-génomes ». Ces biais de plasticité structurale (on parle de compartimentation de la plasticité) se font différentiellement entre les espèces, les chromosomes, les compartiments chromosomiques mais aussi les types de gènes, aboutissant à la diversité structurale observée entre les génomes modernes de plantes. Ces travaux qui rentrent dans le cadre de la recherche fondamentale ont également un fort aspect appliqué à travers la recherche translationnelle en ayant permis de créer des passerelles entre les différentes espèces travaillées en agriculture. Le passage d’une espèce à une autre via les génomes ancestraux fondateurs reconstruits permet notamment le transfert de connaissances des gènes ou de régions d’intérêt des espèces modèles aux espèces cultivées. Les travaux de thèse, par la reconstruction d’ancêtres, permettent une comparaison de haute-résolution des génomes de plantes et in fine l’étude de leur plasticité acquise au cours de l’évolution, et revêtent donc à la fois un aspect fondamental (pour comprendre l’évolution des espèces) mais aussi appliqué (pour l’amélioration des espèces d’intérêt agronomique à partir des modèles). / Angiosperms (or flowering plants) consist in approximatively 350 000 species that have diverged 150 to 200 million years ago in two main families, monocots (orchids, palm trees, banana, bulrushes, grasses...) and dicots (Brassicaceae, Rosaceae, legumes...) representing respectively 20% and 75% of flowering plants. Angiosperms are the subject of intense researches, in particular in genomics since 2000 with the sequence release of the first plant genome (Arabidopsis thaliana) preceding a large number of genomes of plant models and/or species of agronomical interest (around 100 today). Increasing access to plant genome sequences has allowed the identification of their structural diversity, in terms of genome size, number of chromosomes and genes as well as transposable element content. The evolutionary forces that have shaped such structural genomic divergence are at the center of this thesis. Our paleogenomics approach will investigate, through ancestral genome reconstructions, how modern species have diverged from common ancestors and which mechanisms have contributed to such present-day genome plasticity. In this thesis, we have developed methods based on comparative genomics to study plant genome evolution and reconstruct ancestral genomes, extinct progenitors of the modern angiosperm species. An ancestral angiosperm genome has been reconstructed made of 5 chromosomes and 6707 ordered genes allowing the integration in the same model of monocots and eudicots and finally elucidating evolutionary trajectories for species of major agricultural interest such as cereals, rosids and Brassicaceae. The reconstructed paleohistory of modern flowering plants enabled the identification as well as the investigation of the impact of polyploidy events (WGD, whole genome duplications), ubiquitous in plants, as a major driver of the observed structural plasticity of angiosperms. We established that genomes tend to return to a diploid status following a polyploidy event. This structural diploidization is performed at the karyotypic level through chromosomal rearrangements (involving ancestral centromeres and telomeres losses) as well as the gene level (through ancestral duplicates loss). It has been shown that this diploidization is preferentially done on one of the post-polyploidy subgenome, leading to the "sub-genome dominance" phenomenon. This structural plasticity bias (also referenced as plasticity partitioning) is acting differentially between species, chromosomes, chromosomal compartments, gene types, resulting in the structural diversity observed between the present-day plant genomes. This thesis is clearly within the scope of fundamental researches but also has a strong applied objective through translational research in creating bridges between species of major relevance for agriculture. The comparison of one species to another through the reconstructed ancestral genomes allows transferring knowledge gained on genes or any region of interest from model species to crops. Paleogenomics, in reconstructing ancestral genome and unveiling the forces driving modern plant genome plasticity, is therefore of fundamental (toward understanding species evolution) but also applied (toward improving orphan species from knowledge gained in models) objectives.

Au sein des écosystèmes, les Composés Organiques Volatils (COVs) émis par les plantes jouent un rôle majeur dans les interactions trophiques. Ces signaux olfactifs vont renseigner les insectes phytophages sur la présence de leurs hôtes mais permettent aussi de recruter les ennemis naturels. Il a été montré que certains de ces composés pouvaient être utilisés pour manipuler le comportement des insectes phytophages s’attaquant aux cultures. La stratégie push-pull, vise à combiner des stimuli positifs et négatifs pour un insecte ravageur afin de le repousser d’une culture tout en l’attirant sur une plante piège implantée en périphérie du champ où il pourra être contrôlé. L’objectif de cette thèse est d’améliorer notre compréhension et nos connaissances sur la manipulation de la communication chimique entre les plantes et les insectes phytophages à l’aide de COVs de synthèse et de préférence d’hôte afin de mettre en place sur le terrain une stratégie de type push-pull pour protéger une culture de la mouche du chou (Delia radicum). Dans un premier chapitre, nous montrons que dans un système push-pull composé (i) de diffuseur de diméthyldisulfure DMDS (composante push) et (ii) d’une bordure de choux chinois supplémenté avec de l’acétate d’hexenyl (Z-3-HAC) (composante pull), il est possible de modifier fortement le comportement d’oviposition de D. radicum sans impacter de façon négative ses principaux ennemis naturels. Les limites agronomiques et d’utilisation du DMDS atteintes, nous avons recherché d’autres COVs ayant un effet répulsif. Lors d’une seconde expérimentation en push-pull, l’eucalyptol (1-8 cinéol) à permis de réduire le nombre de pupes de D. radicum retrouvées aux pieds des plants de brocoli de 60%. Suite à ce résultat encourageant, nous avons qualifié au laboratoire l’effet inhibiteur de ce monoterpène sur l’oviposition de la mouche du chou et en avons conclu qu’il permet de masquer le bouquet de COVs attractif d’un hôte. L’efficacité de la composante push étant fortement liée à la diffusion des COVs, nous avons ensuite testé au laboratoire et sur le terrain un nouveau type de diffuseur à base de cires végétales, permettant d’émettre l’eucalyptol de manière passive mais régulière pendant plusieurs semaines. L’étude réalisée montre le fort potentiel du diffuseur qui est à la fois bon marché, facile d’utilisation et fiable en terme de diffusion, permettant ainsi d’envisager son utilisation dans des stratégies de lutte intégrée à grande échelle. Parallèlement à l’étude de la composante push, nous avons cherché à améliorer l’efficacité de la composante pull. Le chou chinois (Brassica rapa) permet grâce à sa forte attractivité de capter et détourner la pression de phytophagie de la culture d’intérêt. Nous montrons qu’au sein de sa grande diversité, certaines variétés comme Richi (appartenant à la sous espèce pekinensis) sont préférentiellement attaqué par la mouche du chou, ce qui en fait de bons candidats au développement d’une composante pull efficace. A la lumière de la bibliographie et de nos résultats, nous proposons une réflexion générale sur le système étudié. Ainsi, nous concluons que, au moins dans le cas de la mouche du chou, les COVs ne peuvent probablement pas être les seuls outils considérés dans le développement d’une stratégie push-pull. / Within ecosystems, Volatile Organic Compounds (VOCs) emitted by plants play a major role in trophic interactions. These olfactive signals will inform phytophagous insects about the presence of their hosts, but they also allow to recruit their natural enemies. It has been shown that some of these compounds could be used to manipulate the behaviour of insect crop pests. The push-pull strategy aims at combining positive and negative stimuli to push a pest out of a crop and lure it into a trap crop located in the periphery of the field, where it can be controlled. The objective of this thesis is to improve our understanding and our knowledge on the manipulation of chemical communication between plants and phytophagous insects, using synthetic VOCs and host preference as tools, to protect a crop against the cabbage root fly (Delia radicum). In a first chapter, we show that in a push-pull made of (i) DMDS dispensers as a push component and (ii) chinese cabbage strips supplemented with hexényl acetate (Z-3-HAC) as a pull component, it is possible to strongly reduce oviposition behaviour in D. radicum without impacting its natural enemies. Agronomic limits to the use of DMDS led us to search for other repulsive VOCs. In a second push-pull field experiment, using eucalyptol (1-8 cinéol), reduced by 60% the number of D. radicum pupae produced in the crop. This encouraging result led us to characterize the inhibition effect of this monoterpene in the lab and concluded that it allows to mask the attractive blend of VOCs released by the host. The efficiency of the push component being strongly linked to that of the VOC diffusion, we have then tested both in the laboratory and in the field a new kind of dispenser made of vegetal waxes, allowing to diffuse eucalyptol passively but regularly during several weeks. This study shows the good potential of this device, which is affordable, easy to use and reliable in terms of diffusion, in integrated pest management strategies at a large scale. In parallel of our studies on the push component, we have also sought to increase the efficiency of the pull component. Thanks to its strong attractivity toward D. radicum, Chinese cabbage (Brassica rapa), allows to divert pest pressure from the cash crop. We show that within its important genetic diversity, some cultivars such as Richi (of the pekinensis subspecies) are preferentially attacked by D. radicum, which makes them good candidates to develop an efficient pull component. Using both the literature and our own results, we finally propose a general discussion on the system studied. We conclude that, at least in the case of the cabbage root fly, VOCs are probably not the sole tools to consider when trying to develop a push-pull strategy.