Blackleg is a disease of canola and rapeseed cultivars that is caused by the fungus Leptosphaeria maculans (Desm.) Ces. & de Not., and it is by far the most destructive pathogen of canola in North America. In recent years, blackleg strains belonging to pathogenicity groups (PG) 3 and 4 have been discovered in North Dakota. Recent outbreaks of the disease have added a sense of urgency to characterize the risk these new strains represent for the canola industry and to identify sources of resistance against them. Thus, the objectives of this study were to screen germplasm collections of Brassica rapa, B. napus. and B. juncea for their reaction to PG3 and PG4 and to evaluate the reaction of a sample of currently used canola commercial cultivars grown in North Dakota to PG3 and PG4 as means to estimate the risk these new strains represent. All canola germplasm and commercial cultivars were evaluated in replicated trials in greenhouse conditions using cotyledon bioassays. In 2009 and 2010, the effect of these strains, using five inoculation sequences, on the reaction of canola seedlings was also evaluated. Field trials were not conducted because of the limited geographical distribution of the new strains. No adequate sources of resistance were identified among the 277 B. rapa and 130 B. napus accessions evaluated; however, 22 of the 406 accessions of Brassicajuncea evaluated were considered to have moderate levels of resistance. B. juncea seedlings that survived these inoculations were self-pollinated and their progeny (F1) were also screened. As before, surviving seedlings were self-pollinated. These F2 seeds are the elite materials that could be used in future breeding programs. The complementary study evaluating the role of sequence inoculations in reaction of canola seedlings to blackleg indicated that an increased susceptibility to PG3 occurred when seedlings were first inoculated with PG4; however, reaction to PG4 was not enhanced by a prior inoculation with PG3. All 75 commercial cultivars evaluated were susceptible to PG3 and PG4, indicating that the risk these new strains represent to the canola industry of the region is serious. Further, when a subsample of 16 cultivars were challenged with PG2, they were either resistant or moderately resistant, suggesting the ratings the industry are using relate to reaction of those cultivars to PG2 but not to the new strains; thus, growers should use caution when using these ratings while deciding on which cultivars to plant. / North Dakota State University. Department of Plant Pathology / USDA North Central Canola Research Program / Northern Canola Growers Association

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Les symbiotes d'insectes peuvent considérablement influencer leurs hôtes de diverses manières. Nous avons étudié ici la communauté de microbes de la mouche du chou (Delia radicum) et plus particulièrement le rôle de son microbiote intestinal et de Wolbachia, une bactérie intracellulaire. La transmission verticale et maternelle de Wolbachia était de 100% et nous n’avons trouvé aucune preuve de manipulation de la reproduction telles que l’incompatibilité cytoplasmique, la parthénogenèse thélytoque, la féminisation ou la dégénérescence des embryons mâles. Les effets de Wolbachia sur D. radicum étaient significatifs mais modérés, et se compensaient mutuellement (réduction du taux d’éclosion, meilleure survie larvo-nymphale, temps de développement plus long et augmentation de la mortalité des femelles en conditions de stress), ce qui suggère une infection quasi neutre chez cette espèce, même si nous avons observé une augmentation de la fréquence d’infection en conditions idéales. L'influence du microbiote intestinal a été étudiée en utilisant un antibiotique, la tétracycline, avec un protocole sur trois générations, ce qui a permis de discerner l’effet direct (toxique) de la tétracycline de ses effets indirects (perte de symbiotes) sur l’hôte. Le traitement antibiotique de D. radicum a eu de multiples effets, généralement négatifs, sur les traits d’histoire de vie des descendants, ces effets pouvant être détectés jusqu'à deux générations après le traitement. La perturbation du microbiote intestinal semble avoir un rôle plus important qu'un simple effet toxique de la tétracycline elle-même. De plus, l’étude suggère que le microbiote semble avoir un rôle bénéfique chez cette espèce, et qu’il est au moins partiellement hérité de la mère. Pour finir, nous avons étudié si Wolbachia pouvait modifier le dialogue plante-insecte entre D. radicum et l’une de ses plantes-hôtes, le colza (Brassica napus). La présence du symbiote a diminué les concentrations de glucosinolates dans les feuilles, ce qui suggère que Wolbachia pourrait améliorer la fitness de son hôte en diminuant les signaux chimiques de la plante pouvant être utilisés par les conspécifiques et/ou ennemis naturels de D. radicum. Cette étude a montré le potentiel d'une bactérie intracellulaire à influencer les relations plantes-insectes et a permis de discuter des interactions tri-trophiques entre les symbiotes, leurs insectes-hôtes et un troisième niveau trophique : la plante. Cette thèse démontre qu'il est maintenant nécessaire de prendre en compte les symbiotes dans de prochaines études, afin de mieux comprendre les relations possibles entre différents partenaires, ainsi que leurs implications écologiques ou évolutives. / Microbial symbionts can deeply influence their animal hosts in various ways. Here, we studied the community of microbes of the cabbage root fly (Delia radicum) and more precisely the role of its gut microbiota and of Wolbachia, an intracellular bacterium. The vertical maternal transmission of Wolbachia was perfect, and we found no evidence of manipulation of reproduction such as cytoplasmic incompatibility, thelytokous parthenogenesis, feminization nor male killing. Wolbachia infection had significant but moderate and mutually compensating effects on D. radicum (reduced hatch rate, improved larvo-nymphal viability, longer development time and increased female mortality in stress conditions), suggesting that infection might be nearly neutral in this strain, although we observed an increase in infection frequency in ideal rearing conditions. The influence of the gut microbiota was studied using an antibiotic, tetracycline, with a protocol spanning three generations, which allowed to discriminate the possible direct (toxic) effect of tetracycline from its indirect effects (due to the loss of gut symbionts). Antibiotic treatment of adults led to multiple and mostly negative effects on life history traits of their offspring and grandchildren. Data suggested a larger role of gut microbiota perturbation than of a toxic effect, that the microbiota was partially inherited maternally, and that the “wild-type” gut microbiota was beneficial in this species. Finally, we investigated whether Wolbachia could modify the insect-plant dialogue between D. radicum larvae feeding on roots of oilseed rape (Brassica napus). The presence of the symbiont decreased glucosinolate concentrations in the leaves, suggesting that Wolbachia could increase the fitness of its host by decreasing plant cues used by D. radicum conspecifics and/or natural enemies. This study showed the potential of an intracellular bacteria to influence plant-insect relationships, and allowed to discuss the tri-trophic interactions between symbionts, their insect hosts and a third trophic level: the plant. This thesis demonstrates the necessity to consider intracellular and extracellular symbionts in further studies, in order to unravel all the possible relationships between different partners, as well as their ecological or evolutionary implications.

Projeções de crescimento populacional, do aumento do consumo de alimentos e da escassez de terras agricultáveis apontam para a necessidade de intensificar a produção agrícola, a fim de suprir a demanda mundial. O Brasil é o maior produtor mundial de cana-de-açúcar, sendo o estado de São Paulo responsável por 56% da produção nacional. Nos mais de 4,5 milhões de hectares no estado, a cultura apresenta período de latência do crescimento. Nesse momento de crescimento lento da cana-de-açúcar a introdução de uma cultura de ciclo anual curto faz-se possível. Com base nessa hipótese, a presente dissertação de mestrado se propôs avaliar o desempenho fitotécnico da consorciação de cana-de-açúcar e canola e, particularmente analisar a capacidade produtiva da oleaginosa em ambiente de clima tropical, quantificar a interação com a radiação fotossinteticamente ativa desses cultivos e avançar no estudo de modelagem da cultura da canola. Para isso, foram conduzidos experimentos a campo, durante três anos agrícolas, delineado em blocos casualizados com 4 repetições e 5 tratamentos: cana-de-açúcar + canola Hyola 61; cana-de-açúcar + canola Hyola 401 ou Hyola 571; cana-de-açúcar monocultivo; canola Hyola 61 monocultivo; canola Hyola 401 ou Hyola 571 monocultivo. Além disso, foi conduzido um experimento adicional de produção de canola irrigada delineado no esquema de blocos casualizados com 4 repetições para a calibração do modelo APSIM-Canola. Medidas meteorológicas, de solo e biométricas foram realizadas para caracterizar os sistemas de produção. Os principais resultados evidenciaram que o sistema de consorciação de cana-de-açúcar e canola foi capaz de intensificar o uso da terra, com produtividade das culturas consorciadas similar às obtidas em monocultivo. O aumento da produção do sistema consorciado ocorreu devido a utilização mais eficiente dos recursos ambientais, principalmente da radiação fotossinteticamente ativa. O modelo APSIM-Canola calibrado demonstrou potencialidade de uso para projetar a expansão agrícola da canola, podendo contribuir para o aperfeiçoamento do zoneamento agroclimático da cultura no Brasil. / Projections of population growth, increased food consumption and scarce agricultural land indicate the need to intensify agricultural production in order to meet the world demand. Brazil is the world\'s largest producer of sugarcane, with São Paulo state accounting for 56% of national production. In the more than 4.5 million hectares in the State, the crop has a latency period of growth. At this time of slow growth of sugarcane, the introduction of a short-season crop is possible. Based on this hypothesis, the present Master\'s thesis aimed to evaluate the phytotechnical performance of sugarcane and canola intercropping and, in particular, to analyze the productive capacity of the oilseed in a tropical climate environment, to quantify the interaction with the photosynthetically active radiation of these crops and to advance in the modeling study of canola. For this, field experiments were conducted during three agricultural years, delineated in randomized complete block with 4 replicates and 5 treatments: sugarcane + Hyola canola 61; canola + canola Hyola 401 or Hyola 571; cane sugar monoculture; canola Hyola 61 monoculture; canola Hyola 401 or Hyola 571 monoculture. In addition to that, it was conducted an experiment of irrigated canola production outlined in randomized complete block design with 4 replications for the calibration of APSIM-Canola model. Meteorological, soil and biometric measurements were performed to characterize the production systems. The main results showed that the sugarcane and canola intercropping system was able to intensify land use, with yields of intercropped crops similar to those obtained in monoculture. The increase in the production of the intercropping system occurs due to the more efficient use of the environmental resources, mainly of photosynthetically active radiation. The calibrated APSIM-Canola model showed potential use to project the agricultural expansion of canola, and can contribute to the improvement of the crop\'s agroclimatic zoning in Brazil.

Le colza (Brassica napus) est cultivée pour la richesse de ses graines en lipides et protéines. Cette plante possède aussi des métabolites secondaires bioactifs pouvant moduler la santé du consommateur. Ainsi différentes actions ont été mises en place par les industries agroalimentaires pour réduire le taux de métabolites antinutritionnels. A l’inverse peu sont consacrés à l’exploitation des métabolites favorables à la santé. L’une des pistes est d’identifier les conditions de culture en interaction avec les génotypes pour générer des graines de qualité nutritionnelle optimale. D’une manière générale, les résultats ont montré que certaines variétés sont résilientes à l’environnement. D’autres au contraire se sont montrées plus sensibles. L'impact des IGEC observé a été évaluée sur un modèle préclinique de souris ob/ob par une approche multi-omique, et comparée à celle d’un extrait de référence issu de Brassica oleracea (Brocoli) commercialisé pour ces vertus santé. Les résultats ont montré que la réponse biologique « omique » mesurée dans l’intestin, le foie et le plasma présentait une forte proximité entre l’un des extraits de colza (ES-Mambo) avec l’extrait de référence (Brocoli). Nous pensons que cela résulte de la présence de composés bioactifs communs et minoritaires entre les deux plantes et dont nous avons pu identifier la nature de certains (composés phénoliques et glucosinolates). L’approche métabolomique a démontré que les conditions de culture et le génotype du colza ayant modifié leur contenu bioactif induisaient une réponse biologique différentielle chez le consommateur. Cette preuve de concept pourrait s’appliquer à d’autres plantes de grande consommation. / Rapeseed (Brassica napus) is the first oleaginous crop in France. It is cultivated for the abundance of its seeds in lipids, proteins as wellas for its richness in secondary metabolites that can modulate the health of the consumer. For instance, different actions have beenimplemented by food and feed industries to reduce the rate of anti-nutritional metabolites. Conversely few are devoted to theexploitation of health promoting molecules. A strategy is to identify the genotype x environment x agronomic management interactions(GEAI) to generate seeds of optimal nutritional quality.The results showed that some varieties are resilient to the environment. On the other hand, others appeared more sensitive. The environment and genetic impact was evaluated on a preclinical model ob/ob mouse by a multi-omic approach, and compared to a reference extract from Brassica oleracea (Broccoli), marketed for its health benefits. The results showed that the "omic" biological response measured in the intestine, liver and plasma showed a strong proximity between one of the rapeseed extract (ES-Mambo) and the reference extract (Broccoli). We believe that these results occured from the presence of common bioactive compounds between the two plants (rapeseed and broccoli), that some of them were identified (phenolic compounds and glucosinolates). The metabolomic approach was efficient to estimate the health impact of phytochemical extracts that have never been evaluated before. We demonstrated that the GEAI of rapeseed that modified their bioactive contents induced a differential biological response in the consumer. This proof of concept study could be applied to other food plant products.

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