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Gibberellins (GAs) are endogenous plant hormones that control key aspects of growth and development such as seed germination, shoot growth, flower induction and development, and fruit expansion. Chemical growth regulators that modify GA biosynthesis are used extensively in horticulture to modify plant stature, increasing production costs, manpower and associated environmental risks. An alternative strategy is genetic manipulation of GA metabolism in plants to induce similar phenotypic changes.

Face à l’épuisement du pétrole, l’Europe s’oriente vers la production de bioéthanol 2ème génération à partir de biomasse végétale. L’espèce Miscanthus x giganteus est prometteuse de par son fort rendement et ses faibles impacts environnementaux. Cependant, sa diversité génétique est faible et sa composition de biomasse pas forcément optimale pour produire du bioéthanol 2ème génération. Cette thèse explore donc différentes espèces de Miscanthus pour définir des idéotypes et des pistes en sélection afin d’améliorer le miscanthus pour ce débouché. Trois approches ont été menées : une étude bibliographique, une étude expérimentale au champ et des tests en pilote industriel. L’étude bibliographique montre une forte variabilité environnementale et génotypique pour les caractères associés à la production et à la composition de biomasse. L’analyse des données expérimentales révèle des caractères antagonistes : une forte production de biomasse est associée à de fortes teneurs en cellulose et lignines, mais à de faibles teneurs en hémicelluloses, solubles et cendres. De fortes teneurs en lignines contribuent également à réduire l’efficacité de la transformation de la biomasse en bioéthanol 2ème génération. Enfin, des outils de phénotypage ont été définis : la hauteur de végétation et le volume aérien de la plante permettent de prédire la production de biomasse des stades adultes à partir des stades jeunes. La spectroscopie proche infra-rouge permet aussi de prédire la composition de la biomasse. Ce travail contribue à la définition d’idéotypes de miscanthus pour une valorisation en bioéthanol 2ème génération en proposant des critères, des outils et des perspectives en sélection. / In front of the depletion of oil resources, Europe is moving towards the 2nd-generation bioethanol production from plant biomass. The Miscanthus x giganteus species is promising due to its high biomass production and its low environmental impacts. However, the genetic diversity of this species is low and its biomass composition is not necessary optimal for the 2nd-generation bioethanol production. This thesis therefore aims to explore several Miscanthus species in order to define ideotypes and to propose guidelines to target miscanthus breeding for 2nd-generation bioethanol production. It was based on three approaches: a literature review, an experimental field study, and tests in pilot at industrial scale. The review of literature showed a strong environmental and genotypic variability for traits related to biomass production and composition. Moreover, the experimental data analysis showed antagonisms between the traits of interest: a high biomass production was associated with high cellulose and lignin contents, but low hemicellulose, soluble, and ash contents. High biomass lignin content also reduced the efficiency of the biomass conversion to 2nd-generation bioethanol. Lastly, breeding tools were defined: canopy height and aboveground plant volume enabled to predict the biomass production of mature crops from early stages. The near infrared spectroscopy also provided accurate prediction of the miscanthus biomass composition. This contributes to the definition of miscanthus ideotypes for 2nd-generation bioethanol production by providing selection criteria, breeding tools, and breeding prospects.

Made available in DSpace on 2016-08-29T15:37:39Z (GMT). No. of bitstreams: 1 tese_8368_Tese Final João Felipe de Brites Senra20150914-93412.pdf: 793682 bytes, checksum: 4b0c0e4fa9a46d0ae2e7e1c4102106b4 (MD5) Previous issue date: 2015-02-19 / CAPES / A espécie Euterpe edulis Martius é nativa da Mata Atlântica e conhecida popularmente como palmeira juçara. Esta é uma espécie chave da Mata Atlântica, pois produz frutos que são consumidos por cerca de 30 espécies de aves e 13 espécies de mamíferos além de possuírem um grande potencial econômico para ser explorado na forma de polpa de fruta, doce e sovertes. Atualmente a palmeira juçara encontra-se na lista oficial das espécies ameaçadas de extinção no Brasil. Este trabalho teve por objetivos: estimar o coeficiente de repetibilidade e de determinação de características dos frutos e das sementes, analisar o número de medições para um nível de confiança de 95% e testar diferentes metodologias de estimação da repetibilidade; estudar a diversidade genética entre os acessos e avaliar o padrão de germinação das sementes via modelos não lineares Logístico, Gompertz, Von Bertalanffy e Will Bill; quantificar a diversidade genética interpopulacional da espécie baseada na correlação entre caracteres vegetativos e relacionados à produção de frutos. A coleta dos frutos da palmeira juçara foi realizada em 20 fragmentos florestais nos município da região Sul do estado do Espírito Santo: Alegre (oito fragmentos); Guaçuí (quatro fragmentos); Ibitirama (três fragmentos); Jerônimo Monteiro (um fragmento); Mimoso (três fragmentos); e Muqui (um fragmento). Para o estudo de repetibilidade foram utilizados 198 acessos, 25 frutos por planta, sendo avaliado: diâmetro longitudinal e equatorial do fruto e da semente (DLF, DLS, DEF e DES) em milímetros (mm); massa do fruto e da semente (MF e MS) em gramas (g). A deviance foi estimada pelo método da máxima verossimilhança restrita (REML). Os coeficiente de repetibilidade e determinação e o número de medições necessárias foi realizado utilizando os métodos da REML, componentes principais via matriz de correlações e covariâncias e análise estrutural baseada nas matrizes de correlações e covariâncias. As estimativas dos coeficientes de repetibilidade e determinação de todas as variáveis analisadas são superiores a 0,78 e 98% respectivamente, para todas as metodologias testadas, realizando 25 medições. Para 95% de confiabilidade são necessárias 5 medições para as variáveis DLF, DEF, DLS, DES e MS e 4 medições para a variável MF. As metodologias utilizadas não diferem quanto à estimativa do coeficiente de repetibilidade para as variáveis DLF, DES, MF e MS, enquanto que para as demais variáveis as diferenças foram mínimas. Para a análise de identidade de modelos foram utilizados sementes de 45 acessos sendo avaliado: germinação; índice de velocidade de germinação; tempo médio de germinação; primeira contagem de germinação e a porcentagem de germinação. Com base nos dados quantitativos foi calculada a matriz de distância generalizada de Mahalanobis (D²) e posteriormente os acessos foram agrupados pelo método de otimização de Tocher formando quatro grupos. Em cada grupo a germinação foi analisada via regresão não linear utilizando os modelos de Logístico, Gompertz, Von Bertalanffy e Will Bill. O ajuste dos modelos foi avaliado pelo coeficiente de determinação (R²), quadrado médio do resíduo (QMR), desvio médio absoluto (DMA), critério de informação de Akaike (AIC) e critério de informação Bayesiano (BIC). O teste de identidade de modelos foi realizado pelo teste F. O modelo de Gompertz apresentou valores de β1, β2 e β3 intermediários aos demais modelos o que evita a sub ou super estimação destes parâmetros da regressão, além disso, este modelo apresenta os maiores valores de R2 e os menores valores do QMR, DMA, AIC e BIC sendo o mais indicado para descrever o padrão de germinação. O teste de identidade de modelos foi não significativo e desta forma uma única regressão não é eficiente para descrever o processo germinativo. Os grupos três e quatro possuem os maiores valores da TG indicando um maior vigor e para produção de mudas o tempo ideal para o transplantio seria de 30 dias para os grupos um, dois e quatro e 22 dias para o grupo três. Para o estudo de diversidade genética foram utilizados os dados dos frutos dos 198 acessos utilizados na análise de repetibilidade. Neste caso foram avaliados os caracteres: massa de cem frutos (MCF) e massa de cem sementes (MCS) em gramas; rendimento em polpa (RP) em porcentagem; diâmetro do caule a 1,5 m do solo (D1,5), diâmetro do caule a 1,0 m do solo (D1,0) e diâmetro do caule a 0,5 m do solo (D0,5) em milímetros; número de cachos (NC); comprimento do cacho (CC) em centímetros; número de ráquilas (NR); e altura até o cacho (AC) em metros. Com base nestes dados foi estimada a correlação genética, uma análise de componentes principais e análise de correspondência. A correlação genética entre os caracteres MCF x NR (0,44) é positiva. A característica NR é a principal determinante na variação da MCF e a seleção indireta poderá ser eficaz, dependendo de suas estimativas da herdabilidade. Os fragmentos GU3, AL4, JM1, MI1 e MQ1 oriundos de municípios diferentes são os que apresentam maior divergência genética interpopulacional entre os 20 fragmentos estudados. Os fragmentos GU2, GU3 e AL4 possuem indivíduos produtores de massa de cem frutos extragrandes (211,54 a 352,24 g) o que os tornam importantes fontes de seleção para utilização em programas de melhoramento genético da palmeira juçara visando a produção de polpa de fruta. / The species Euterpe edulis Martius is native to the Atlantic Forest and popularly known as jussara palm. It is a key species of the Atlantic Forest, producing fruits that are consumed by about 30 bird species and 13 mammal species, and also presenting great economic potential for exploitation of its fruit in the form of pulp, sweets and ice creams. Currently the jussara palm is on the official list of endangered species in Brazil. The objectives of this study were to: estimate the coefficient of repeatability and determination of the characteristics of fruits and seeds, analyze the number of measurements for a 95% confidence level and test different methods for estimation of repeatability, study the genetic diversity among accessions and evaluate the pattern of seed germination via the Logistic, Gompertz, von Bertalanffy and Will Bill nonlinear models, quantify the inter-population genetic diversity of the species based on the correlation between plant traits and related to fruit production. Collection of the jussara palm fruits was performed in 20 forest fragments in the following municipalities in the southern region of the state of Espírito Santo: Alegre (eight fragments), Guaçuí (four fragments), Ibitirama (three fragments), Jerônimo Monteiro (one fragment), Mimoso (three fragments) and Muqui (one fragment). For the study of repeatability 198 accessions were used, 25 fruits per plant, evaluating: longitudinal and equatorial diameter of the fruit and seed (DLF, DLS, DEF and DES) in millimeters (mm), and fruit and seed mass (MF and MS) in grams (g). Deviance was estimated by the restricted maximum likelihood (REML). The coefficient of repeatability and determination and the required number of measurements was determined using the REML methods, principal components via the correlation matrix, and covariances and structural analysis based on correlation and covariance matrices. Estimates of the repeatability coefficients and determination of all variables analyzed were greater than 0.78 and 98% respectively, for all tested methodologies, performing 25 measurements. For 95% reliability, 5 measurements are required for the variables DLF, DEF, DLS, DES and MS and 4 measurements for the variable MF. The methods used do not differ with respect to estimate of the repeatability coefficient for the variables DLF, DES, MF and MS, while for the other variables the differences were minimal. To analyze the identity of the models, seeds from 40 accessions were used to evaluate: germination, germination speed index, mean germination time, first germination count and the germination percentage. Based on the quantitative data the generalized Mahalanobis distance matrix (d²) was calculate and later accessions were clustered by the Tocher optimization method divided into four groups. In each group germination was analyzed via non-linear regression using the Logistic, Gompertz, von Bertalanffy and Will Bill models. Fit of the models was evaluated by the determination coefficient (R²), residual mean error (QMR), mean absolute deviation (MAD), Akaike information criterion (AIC) and Bayesian information criterion (BIC). The identity test of the models was performed by the F-test. The Gompertz model showed intermediary values of β1, β2 and β3 compared to other models which avoid under or over estimation of these regression parameters; in addition, this model presents the highest R 2 values and the lowest values of QMR, DMA, AIC and BIC, and is the most indicated to describe the pattern of germination. The identity test of the models was not significant and therefore a single regression is not efficient to describe the germination process. Groups three and four have the highest values of TG, indicating greater vigor, and for seedling production the ideal time for transplanting would be 30 days for groups one, two and 4, and 22 days for group three. For the study of genetic diversity, data from fruit of the 198 accessions utilized in the analysis of repeatability were used. In this case we evaluated the traits of: mass of one hundred fruits (MCF) and mass of one hundred seeds (MCS) in grams, pulp yield (RP) in percentage, stem diameter at 1.5 m above the ground (D1,5), stem diameter at 1.0 m above the ground (D1,0) and stem diameter at 0.5 m above the ground (D0,5) in millimeters, number of clusters (CN), cluster length (CC) in centimeters, number of rachilles (NR), and height of the cluster (AC) in meters. Based on these data the genetic correlation was estimated, and a principal components analysis and correspondence analysis were performed. Genetic correlation between the traits MCF x NR (0.44) is positive. The characteristic NR is the main determinant in variation of MCF and indirect selection can be effective, depending on estimates of heritability. The fragments GU3, AL4, JM1, MI1 and MQ1 from different municipalities are those that presented the greatest inter-population genetic divergence among the 20 fragments studied. The fragments GU2, GU3 and AL4 have exceptionally large individual producers regarding the mass of one hundred fruits (211.54 to 352.24 g) which make them important sources of selection for use in jussara palm breeding programs focused on the production of fruit pulp.

Le climat, la qualité de l’air et la sécurité énergétique ont changé la façon de produire l’énergie, accroissant la demande en cultures énergétiques comme M. x giganteus. Néanmoins, élargir la diversité de cette espèce est nécessaire afin de couvrir une large gamme de pédo-climats. L’objectif est donc de définir des caractères d’intérêt pour mener à bien une collecte de miscanthus en Chine, un des pays où cette plante est originaire. 44 clones sauvages de trois espèces de Miscanthus (M. sinensis, M. sacchariflous, M. floridulus) ont été collectés dans différentes régions Centre, Sud et Ouest de la Chine et multipliés à Linan dans la province chinoise de Zhejiang. En France, nous avons étudié 21 clones implantés à l’INRA d’Estrées-Mons appartenant à 3 espèces (M. x giganteus, M. sinensis and M. sacchariflorus). La thèse comporte cinq chapitres. 1) La bibliographie décrit le miscanthus au niveau de sa taxonomie, de son origine géographique, de son aptitude à produire de la biomasse et de sa résistance à différents stress. 2) Les caractères les plus importants ont été identifiés pour reconnaître les espèces. 3) Nous avons découvert que les M. x giganteus ont un génome maternel commun à des M. sacchariflorus chinois. 4) Parmi les clones sauvages Chinois, M. floridulus présente le plus d’intérêt pour produire de la biomasse. 5) Enfin, nous avons mis en évidence les facteurs physiologiques et biochimiques expliquant l’effet de la disponibilité en azote sur la photosynthèse sur 3 espèces. Ainsi, la plupart des caractères qui ont été mis en évidence au sein de cette thèse vont être utiles pour la collecte de matériel végétal et les programmes de sélection du miscanthus. / Climate, air quality and energy security have recently changed the way energy is supplied and increases the demand for bioenergy crops such as M. x giganteus. However, this species needs to enlarge its diversity to fit different growth conditions. The objective is therefore to identify traits of interest to drive the collecting of miscanthus in China, one of the countries where this plant comes from. 44 wild clones of three species of Miscanthus (M. sinensis, M. sacchariflous, and M. floridulus) were collected from the different regions of central-south-east in China and were propagated in Linan of Zhejiang province of China. In France, we studied 21 clones of three species (M. x giganteus, M. sinensis and M. sacchariflorus) which were established at INRA experimental unit in Estrées-Mons. The thesis is composed of five chapters. 1) The bibliography described miscanthus on the base of its taxonomy, geographical origin, biomass production ability and resistance to different stresses. 2) The most important traits were identified for the recognition of the species. 3) We discovered that the clones of M. x giganteus had maternal genome identical to wild relatives of some of the wild M. saccahariflorus. 4) Among the wild Chinese clones, M. floridulus was the most interesting for biomass production. 5). Finally, we highlighted the physiological and biochemical factors under the influence of nitrogen supply on the photosynthesis of miscanthus. Finally, we concluded that most of the traits we highlighted here will be helpful for future germplasm collection and breeding program of miscanthus.