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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Origines, domestication et diversification variétale chez l’olivier (Olea europaea L.) à l’ouest de la Méditerranée / Origins, domestication and varietal diversification in Olive (Olea europaea L.) in western Mediterranean area.

Haouane, Hicham 22 December 2012 (has links)
Les oliviers cultivés et leurs parents sauvages (oléastres), représentent deux variétés botaniques de l'espèce Olea europaea, subsp. var. europaea et var. sylvestris, respectivement. Selon des études génétiques et archéobotaniques antérieures, l'existence de populations d'oléastres dans l'est et l'ouest du bassin méditerranéen remonte à avant le néolithique. La domestication de l'olivier aurait eu lieu au moins dans ces deux zones. Néanmoins, la lignée maternelle qui caractérise les oléastres de l'est de la Méditerranée est majoritaire au sein des variétés méditerranéennes. Une telle signature génétique est probablement le résultat de migrations humaines essentiellement d'est en ouest. En dépit de ces travaux, les origines et les processus de diversification à l'ouest de la méditerranée demeurent méconnus. L'objectif de cette thèse est d'étudier les origines et les processus de diversification chez l'olivier à l'ouest de la Méditerranée. Deux hypothèses sont formulées: (i) une co-existence entre variétés sélectionnées localement et variétés introduites à partir de l'est de la Méditerranée et maintenues par clonage, (ii) une sélection à partir des formes de l'est introgressées par les populations locales à l'ouest de la Méditerranée. Dans une première partie, nous avons examiné les processus de diversification par une analyse des pratiques paysannes à une échelle localisée et dans une zone d'extrême diffusion : le Maroc. Il s'agissait de comprendre comment les paysans traitent la diversité variétale dans un contexte fortement impacté par une seule et même variété, la ‘Picholine marocaine'. Sur la base d'enquêtes semi-dirigées menées auprès des paysans dans les agro-écosystèmes traditionnels et selon une approche d'ethnobiologie, nous avons mis en évidence l'importance des logiques de classifications locales (usage, origine, âge, conservation de l'huile, méthode de propagation…) dans le traitement, le maintien et la gestion de la diversité variétale. Nos résultats montrent la présence d'un système de dénomination basée sur des catégories englobantes où les types d'oliviers sont regroupés sous des noms génériques en fonction des critères socioculturels et techniques plutôt que sur des critères morphologiques. Nous avons montré que ces catégories sont définies par des contours permissifs permettant aux types d'oliviers d'être classées dans plusieurs catégories. Nous soutenons l'hypothèse que ce système de classification permet de maintenir la diversité et est une force motrice pour la diversification variétale dans ces agro-écosystèmes caractérisés par une faible diversité d'oliviers. Dans une seconde partie, nous avons examiné les processus de diversification variétale par une approche basée sur la phylogéographie à l'échelle de la Méditerranée. Les analyses génétiques des variétés méditerranéennes d'olivier basées sur l'utilisation des marqueurs microsatellites nucléaires et chloroplastiques selon une approche bayésienne montrent une structure génétique est-ouest. La plupart des variétés de l'ouest de la méditerranée ont une lignée maternelle de l'est mais un génome nucléaire proche du "pool" génétique de l'ouest de la Méditerranée, ce qui indique une sélection à partir des formes de l'est introgressées par le "pool" génétique ouest et suggère que la sélection des oliviers à partir du semis n'a pas cessé aux premières étapes de domestication. Nos analyses sur les pratiques paysannes montrant que l'oléastre issu de semis fait partie intégrante de l'agro-écosystème et fait l'objet de sélection et d'usage (greffage sur oléastre, utilisation de l'huile de l'oléastre), ce qui plaide en faveur de l'hypothèse de l'introgression. En adoptant l'approche ABC (Approximative Bayesianne Computation), nous montrons que le scénario basé sur l'introgression des oliviers de l'est par les oléastres de l'ouest est le plus probable avec une introgression. / Olive cultivars and their wild relatives (also named oleasters) represent two botanical varieties of Olea europaea subsp. europaea, respectively var. europaea and var. sylvestris. Archaeobotanical and genetic studies showed the occurrence of Oleasters populations in east and west Mediterranean areas before the Neolithic. The domestication of the olive tree has taken place at least in these two areas. However, the maternal lineage that characterizes the eastern Mediterranean oleasters predominates among Mediterranean olive varieties. Such genetic signature is probably the result of human migrations mainly from east to west. Nevertheless, the origins and processes of olive diversification in the western Mediterranean remain unknown. The objective of this thesis is to study the origins and processes of olive diversification in the western Mediterranean areas. Two assumptions are formulated: (i) a co-existence between locally selected and introduced olive varieties from the eastern Mediterranean and maintained by cloning, (ii) a selection from the eastern olive varieties and their introgression by local populations of the western Mediterranean pool. Firstly, we examined the process of olive diversification through analysis of farming practices on a localized scale and in an area of extreme diffusion, in Morocco. Our aim is to understand how farmers treat the olive varietal diversity in a highly impacted context by a single variety, the ‘Picholine marocaine'. Based on semi-structured surveys conducted with farmers in traditional agro-ecosystems and using an approach of ethnobiology, we highlighted the importance of local classification logic (use, origin, age, conservation oil, propagation methods ...) in the treatment, maintenance and management of the varietal diversity. Our results show the presence of a naming system based on inclusive categories which olives types are grouped under generic names based on cultural and technical criteria rather than morphological criteria. We have shown that these categories are defined by permissive contours allowing the olive types to be classified in several categories. We support the hypothesis that this classification system helps to maintain diversity and is a driving force for varietal diversification in these agro-ecosystems characterized by a low diversity of olive trees. Secondly, we examined the varietal olive diversification process by an approach based on a phylogeographic study at a Mediterranean scale. Genetic analyses of Mediterranean olive varieties based on the nuclear and chloroplast microsatellites markers and a Bayesian approach show an east-west genetic structure. Most of western olive varieties have a maternal lineage of the oleasters Mediterranean east, but a nuclear genome close to the gene pool of western Mediterranean, indicating a selection from the eastern forms that were introgressed by the western Mediterranean gene pool and suggests that selection from seedling has not ceased in the early stages of domestication. Our analyzes on the farmers' practices show that oleasters from seedling is an integral part of the agroecosystem and are subject to selection and use (grafting, use of oil oleasters), which argues in favor of the introgression hypothesis. By adopting the ABC approach (Approximate Computation Bayesianne), we show that the scenario based on the introgression of olive varieties of the east by the western oleasters is the most likely scenario. We enrich the knowledge about the domestication process in the western Mediterranean by crossing analysis of farmers' practices and phylogeographic study of olive trees in the Mediterranean basin. Results were discussed with respect to ex-situ versus in-situ conservation and with the questions raised by the evolution of plant diversity involving clonal and sexual propagation.
92

Genetic analysis of seed and flower colour in flax (Linum usitatissimum L.) and identification of a candidate gene in the D locus

2013 August 1900 (has links)
Flax (Linum usitatissimum L.) is a commercial oilseed crop in Canada. Globally flax is known for industrial oil and fiber. Flaxseed contains Omega 3 fatty acid, lignans like secoisolariciresinol diglucoside (SDG), flavonoids and polysaccharides which offer potential health benefits. Conventional flax cultivars are brown seeded and few mutant lines are yellow seeded. The darkness of seed colour depends on the presence of polymerized proanthocyanidins (PA; condensed tannins) in the seed coat. PAs are the product of the phenylpropanoid pathway. Previous genetic studies by Mittapalli and Rowland (2003) on G1186/94 showed the seed colour trait was governed by the homozygous recessive alleles at D locus and the same locus is closely linked to white or pink flower petals. To start with, single seeds of already developed stable recombinant inbred lines (RILs) (of F8:9 generation) from a cross of yellow seeded European recessive line (G1186/94) and brown seeded CDC Bethune (popular variety) were grown. In this study, seed colour phenotyping was done by measuring seed colour of each RIL in Red-Green-Blue (RGB) values. To understand the genetic basis of flax seed and flower colour, mapping with single sequence repeats (SSRs) and CAPS (Cleaved Amplified Polymorphic Sequences) markers were used. For the first time, a framework genetic linkage map was constructed from populations of CDC Bethune/ G1186/94 containing 19 linkage groups (LGs). LG 1 with four SSR markers was found to be linked with the seed colour locus D. During the fine-mapping, two SSR markers (LuM566 and Lu2351) were found to be linked with the seed colour trait. The D locus has been confined in a 2.8 cM region and the closest marker was LuM566 at a distance of 0.6 cM. This was observed to be a stable locus in two growth trials and in different environments with logarithm of odds (LOD) above 39 and more than 84 % of the trait expressed by the major locus in both trials. As there were no recombinants (off types) for flower colour in F8:9 plants i.e brown-seeded lines produced blue flowers and yellow-seeded lines produced white flowers, the same locus holds well for the flower colour trait. The marker associated with seed and flower colour in G1186/94 (European recessive yellow line) was identified and can be used in flax breeding. Additionally, an interesting putative candidate gene of potential significance was identified through genomics assisted gene search from the flax whole genome sequence database. The gene expression analyses showed lower expression of putative flavonoid 3’ hydroxylase (F3’H) (a gene involved in flavonoid biosynthesis pathway) in both seed coat and flower petal tissues of G1186/94 as compared to CDC Bethune. Therefore, this study represents the first report on genetic mapping based putative candidate gene finding for recessive yellow seed colour mutation in the D locus in flax.
93

Modelagem espacial do fluxo de sementes de Jatobá (Hymenaea courbaril), através de marcadores moleculares, na paisagem fragmentada do Pontal do Paranapanema, SP. / Spatial modeling of the seed flow for Hymenaea courbaril with ssr, in a fragmented landscape at Pontal do Paranapanema, Brazil.

Toledo, Renato Miazaki de 17 June 2005 (has links)
Intervenções conservacionistas baseadas em receitas generalistas e uniformes têm eficácia comprometida por serem incapazes de incorporar as particularidades de cada ecossistema e as diferentes características regionais da atividade humana. Este trabalho teve como objetivo desenvolver uma metodologia que incorporasse a avaliação espacial do fluxo gênico contemporâneo de plantas ao planejamento territorial de paisagens fragmentadas. Adotou-se o Jatobá (Hymenaea courbaril), espécie zoocórica, como espécie guarda-chuva. Localizada no Pontal do Paranapanema, a área amostral utilizada possui 49km2, que abrigam sete sub-populações de Jatobá e 1,32 km2 de remanescentes florestais divididos em 4 fragmentos. Executamos o censo de árvores adultas e amostragem regular de indivíduos juvenis. Amostrou-se 359 indivíduos, dos quais 75 foram considerados como adultos, todos foram georreferenciados por GPS e genotipados por SSR. Analisando-se três locos de DNA genômico e um de c-DNA, foram realizados 21.225 testes de maternidade, nos quais 62 plantas jovens tiveram suas mães identificadas. A distribuição das distâncias de dispersão de sementes verificada indica que o isolamento para recolonização entre sub-populações ocorre em distâncias superiores a 1600m. Foram localizados 13 fragmentos que permaneceriam em condição de isolamento, mesmo após a recuperação de todas as APPs. Recomenda-se a inclusão do aumento de conectividade destas manchas, bem como do reflorestamento de todas as APPs, na lista de prioridades do planejamento da conservação da biodiversidade desta região. / Conservationist interventions, based on general and uniform protocols, lose effectiveness by being incapable to incorporate the particularities of each ecosystem and the different regional patterns of the human activity. This research meant to develop a method that incorporates the spatial evaluation of the contemporary gene flow of plants to the territorial planning of fragmented landscape. We adopted Hymenaea courbaril as an umbrella species. Located in the Pontal of the Paranapanema (São Paulo State, Brazil), the study area has 49km2, that shelters seven subpopulations of Hymenaea courbaril with 1,32km2 are covered by forest that is separated in four patches. We censused adult trees and also regular seedlings and juveniles were regularly sampled. A total of 359 individuals were identified and georreferencered by GPS and genotyped by SSR. Analyzing 3 loci of genomic DNA and one of c-DNA, we applied a maternity test. 62 young plants had them mothers identified. The distribution of distances of seed dispersal indicates that the isolation for recolonization between subpopulations occurs in distances greater than 1600m, indicating that the connectivity in the studied landscape is very low for Hymenaea courbaril. 13 habitat patches were located in isolation condition, even after the recuperation of all the law-protected riparian-corridor areas. These results emphasized the increase of connectivity of these spots, as well as the restoration in the protected riparian areas, as some of the top priorities in the planning of the biological conservation of this region.
94

Transferibilidade e variabilidade genética de marcadores microssatélites gênicos em Egenia klotzschiana Berg (Myrtaceae) / Transferability and genetic variability of microsatellite markers genec Eugenia klotzschiana Berg (Myrtaceae)

Siqueira, Mariana Natalice de 11 August 2014 (has links)
Submitted by Luanna Matias (lua_matias@yahoo.com.br) on 2015-02-06T20:08:28Z No. of bitstreams: 2 Dissertação - Mariana Natalice de Siqueira - 2014..pdf: 2279133 bytes, checksum: 6e154dbf06fec9fd7fd142269ced0028 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-02-19T14:38:22Z (GMT) No. of bitstreams: 2 Dissertação - Mariana Natalice de Siqueira - 2014..pdf: 2279133 bytes, checksum: 6e154dbf06fec9fd7fd142269ced0028 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-02-19T14:38:22Z (GMT). No. of bitstreams: 2 Dissertação - Mariana Natalice de Siqueira - 2014..pdf: 2279133 bytes, checksum: 6e154dbf06fec9fd7fd142269ced0028 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-08-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Eugenia klotzschiana Berg is a species of Myrtaceae with restricted distribution in the Cerrado. Its fruits present nutritional potential and can be used in extractive way, as raw material for production of jams, jellies and juices. In this context, it is necessary to evaluate population-genetic aspects in order to provide information to assist in targeting strategies for management and conservation. To assess the genetic variability in a population context microsatellite markers have been used in recent years. The sequences flanking the microsatellite regions of the genome are highly conserved between related species, enabling the portability of these markers, reducing thereby the costs of developing the same for each species under study. In this context, the aim of this study was to test the potential for transferability to the genome of E. klotzschiana of genic microsatellite markers developed for Eucalyptus, as well as to characterize the genetic variability in their populations. For this purpose, DNA was extracted from leaf tissue of E. klotzschiana individuals and used to test the cross 120 pairs of amplification primers. Samples from seven locations were used to characterize the population genetic variability. The amplification products were analyzed on agarose and polyacrylamide capillary electrophoresis gel in different stages. Of total primers tested, 67 (55.83%) did not amplify, 42 (35%) had many nonspecific amplification products and 11 (9.2%) were successfully transferred. Of the 11 transferred eight showed polymorphism. For the eight polymorphic markers, the probability of identity was high (2.02 x10-3) and the power of paternity exclusion was moderated (0.74). In this population the average value of expected heterozygosity (He) was 0.28 and observed heterozygosity (Ho) was 0.44, as in subpopulations of He mean values ranged from 0.18 to 0.27 and the mean values Ho ranged from 0.36 to 0.53, respectively. No significant for the fixation index (f) were observed in the populations values indicating allele frequencies below the expected Hardy-Weinberg proportions.The extent of genetic divergence among subpopulations showed relatively high genetic differentiation, with a value of θ equal to 0.20, and peerto- peer values ranging between 0.00 and 0.34. The strategy of transferability of microsatellite markers was efficient to generate a panel of polymorphic microsatellite markers and learn a little of the genetic variability of the species. It was possible to verify that there is a low genetic variability within subpopulations for biomarkers. However, this work is a starting point for future studies to better understand the reproductive biology of the species Eugenia klotzschiana. / Eugenia klotzschiana Bergé uma espécie da família Myrtaceae com distribuição restrita no Cerrado. Seus frutos apresentam potencial alimentício e podem ser utilizados de forma extrativista,como matéria-primapara produção de doces, geleias e sucos. Neste contexto, torna-se necessário a avaliação de aspectos genético-populacionais a fim de disponibilizar informações que auxiliem no direcionamento de estratégias de manejo e conservação. Marcadores microssatélites têm sido utilizados nos últimos anospara avaliar a variabilidade genética em um contexto populacional. As sequências que flanqueiam as regiões microssatélites no genoma encontram-se altamente conservadas entre espécies relacionadas, o que possibilita a transferibilidade destes marcadores, reduzindo, desta forma, os custos de desenvolvimento dos mesmos para cada uma das espécies que se pretende estudar. Nesse contexto, o objetivo do presente estudo foi testar o potencial de transferibilidade para o genoma de Eugenia klotzschiana, de marcadores microssatélites gênicos desenvolvidos para Eucalyptus, assim como caracterizar a variabilidade genética existente em suas populações. Para tanto, o DNA foi extraído a partir de tecido foliar de indivíduos de E. klotzschianae utilizado para testar a amplificação cruzada de 120 pares de primers. Amostras oriundas de sete localidades foram utilizadas para a caracterização da variabilidade genética populacional. Os produtos de amplificação foram analisados em gel de agarose, poliacrilamida e emeletroforese capilar, em diferentes etapas. Do total deprimers testados, 67 (55,83%) não amplificaram, 42 (35%) apresentaram muitos produtos de amplificação inespecíficos e 11 (9,2%) foram considerados transferidos com sucesso. Dos 11 transferidos, oito apresentaram polimorfismo. Para os oito marcadores polimórficos, a probabilidade de identidade foi alta (2,02x10-3) e o poder de exclusão de paternidade foi moderado (0,74). Na população, o valor médio da heterozigosidade esperada (He) foi de 0,28 e a heterozigosidade observada (Ho) foi de 0,44, já nas subpopulações os valores médios de He variaram de 0,18 a 0,27 e os valores médios de Ho variaram de 0,36 a 0,53.Não foram observados valores significativos para o índice de fixação (f) nas subpopulações, indicando que as frequências alélicas seguem as proporções esperadas pelo equilíbrio de Hardy-Weinberg. A medida de divergência genéticaentre as subpopulações apresentou diferenciação genética relativamente alta,com valor de θigual a0,20, e com valores par-a-par variando entre 0,00 e 0,34. A estratégia de transferibilidade de marcadores microssatélites foi eficiente para gerar um painel de marcadores microssatélites polimórficos e conhecer um pouco da variabilidade genética da espécie. Foi possível verificar que existe uma baixa variabilidade genética dentro das subpopulações para os marcadores avaliados. Todavia, esse trabalho é um ponto de partida para futuros estudos que permitam conhecer melhor a biologia reprodutiva da espécie Eugenia klotzschiana.
95

Just Tweet It: Sports Teams' Communication of CSR on Twitter

Stephan, David Paul 01 June 2016 (has links)
The sports industry has been made distinct from traditional business for many reasons including its body of stakeholders and its position in popular media. For these reasons, corporate social responsibility (CSR) efforts and the communication of them in professional sports is known to be addressed differently. The following research has been conducted in order to learn how well professional sports teams are doing to communicate CSR to the particular stakeholders who are also their social media followers. Sports teams' Twitter accounts were analyzed and tweets concerning CSR were identified. Findings suggested that only 3.94% of professional sports teams' tweets were related to CSR. It was also found that intrinsically, market size and on-field team performance do not affect CSR tweeting. When viewed together, however, it has been found that smaller market losing teams tweet more CSR than larger market losing teams while smaller market winning teams tweet less CSR than larger market winning teams. This finding lends insights into the strategic purposes of CSR in the professional sports industry. When small market sports teams do not have a successful season, they seem to restore their reputation via the CSR function more so than larger market teams in a similar situation do. Additionally, winning teams of the larger market tweet more CSR than smaller market winners. The conclusion is that, although relatively little CSR tweeting is done in professional sports, smaller market professional sports teams' CSR tweeting is spurred by poor performance, whereas larger market sports teams' CSR tweeting is spurred by winning.
96

Characterization and molecular mapping of drought tolerance in kabuli chickpea (<i>Cicer arietinum L.</i>)

Rehman, Aziz Ur 12 January 2009
Abstract Drought is the most common abiotic stress limiting chickpea production in the world. Ninety percent of the worlds chickpea is produced in areas relying upon conserved, receding soil moisture, therefore, crop productivity is largely dependent on efficient utilization of available soil moisture. Because of the variability in drought pattern from year to year, trait based selection could have an advantage over selection on the basis of grain yield alone. Trait based breeding, however, requires trait dissection into components. Successful marker identification would facilitate integration of MAS procedures in breeding programs enabling the pyramiding of favourable alleles.<p> The genetic map produced in this study was based on a population of recombinant inbred lines of a cross of ILC 588 x ILC 3279 containing 52 SSR markers spanned 335 cM of the chickpea genome at an average density of 6.4 cM. A total of 13 genomic regions were shown to be associated with drought tolerance traits. Some of these genomic regions showed pleiotropic effect on multiple traits. This was also supported by the analysis of phenotypic data where these traits were found to be correlated. For example, early flowering and maturity had a strong association with high grain yield. High grain yield was also associated with better portioning ability between biomass and grain yield, i.e. harvest index. Drought tolerance score (DTS) was associated with various important traits including biomass, early flowering, early maturity.<p> This study also concluded that chickpea genotypes differed in terms of root length, root length density, root weight density and root length to weight ratio at every 20 cm soil layer up to 100 cm depth in response to water deficits. Consideration of an efficient root system vs. a larger root system is also important, since in this research, large root systems were offset by low harvest index, presumably due to the lack of assimilate available for grain growth. A restricted root system is important in environments like Western Canada, where crop growth termination is usually required prior to fall frost. This study also reported significant associations of stomatal conductance (gs) with each of HI, grain yield under drought, drought susceptibility index and drought tolerance score (DTS). Stomatal conductance can also be used to assess plant stress due to drought. Values of gs less than 250 mmol m-2s-1 during flowering indicated drought stress under greenhouse conditions. A higher degree of plant stress due to drought was shown by increased stomatal closure at midday (gs <150 mmol m-2s-1). The study of 157 RILs under natural drought stress during 2005-07 revealed that the 17 RILs which had high grain yield under drought (Group A), also tended to have higher gs than the 42 RILs that had lower grain yield (Group B). Group A had mean gs values of 390 mmol m-2s-1 during the week before flowering, while Group B had mean gs value of 330 mmol m-2s-1. Stomatal conductance increased at flowering and then sharply decreased later in the reproductive period, particularly in Group B. These findings were also supported by canopy temperature differential measurements as Group A was also able to maintain lower canopy temperature than Group B, indicating the ability of these plants to maintain adequate transpiration and a cooler canopy under drought stress. This research indicated that gs and canopy temperature can be used to assess chickpea drought stress and to screen drought tolerant genotypes. This study identified a QTL on LG7 for gs, QTLs on LG1, LG3 and LG6 associated with canopy temperature differential, as well as QTLs associated with grain yield under drought, HI, DTS, days to flower, days to maturity, reproductive period and plant height. These QTLs identified for traits related to higher chickpea productivity under drought stress could have important implications for accelerating the process of pyramiding of favourable genes into adapted genotypes and on future marker-assisted breeding for drought prone areas.
97

Genetic analysis, QTL mapping and gene expression analysis of key visual quality traits affecting the market value of field pea

Ubayasena, Lasantha Chandana 15 April 2011
Visual quality is one of the major factors that determine the market value of field pea (Pisum sativum L.). Breeding for improved visual quality of pea seeds is currently a challenging task, because of the complexity and lack of sound genetic knowledge of the traits. The objectives of this research were to characterize the genetic basis and identify the genomic regions associated with four key visual quality traits (cotyledon bleaching in green pea, greenness in yellow pea, and seed shape and seed dimpling in both green and yellow types) in field pea. Biochemical and gene expression profiling to understand the molecular basis of post-harvest cotyledon bleaching in green pea was also addressed. Two F5:6 recombinant inbred line (RIL) populations (90 lines from Orb X CDC Striker cross, and 120 lines from Alfetta X CDC Bronco cross) were developed and evaluated for visual quality traits in two locations in Saskatchewan, Canada in 2006 and 2007. The four quality traits evaluated all displayed a continuous range of expression with moderate to high heritability. Two genetic linkage maps utilizing 224 markers (29 simple sequence repeat (SSR) (from Agrogene) and 195 amplified fragment length polymorphism (AFLP)) and 223 markers (27 SSR and 196 AFLP ) were constructed for the Orb X CDC Striker population and the Alfetta X CDC Bronco population, respectively. Multiple quantitative traits (QTL) mapping detected major QTLs on linkage group (LG) IV and LG V, as well as location- and year-specific QTLs on LG II and LG III associated with green cotyledon bleaching resistance. Nine QTLs controlling yellow seed lightness, three for yellow seed greenness, 15 for seed shape and nine for seed dimpling were detected. Among them, 5 QTLs located on LG II, LG IV and LG VII were consistent in at least two environments. The QTLs and their associated markers will be useful tools to assist pea breeding programs attempting to pyramid positive alleles for the traits. The bleaching resistant cultivar CDC Striker had a slower rate of chlorophyll degradation in cotyledons and a higher carotenoid to chlorophyll ratio in seed coats than the bleaching susceptible cultivar Orb when seed samples were exposed to high intensity light. An oligo-nucleotide microarray (Ps6kOLI1) was utilized to investigate the gene expression profiles of CDC Striker and Orb seed coats at different developmental stages. It clearly indicated that the expression of genes involved in the production and accumulation of secondary metabolites was significantly different between these cultivars. The results of both biochemical and gene expression studies suggested the bleaching resistance in CDC Striker was not due to the accumulation of chlorophyll pigments in the cotyledons, but rather due to the ability of seed coats to protect them from photooxidation. Accumulation of specific carotenoids which could bind with the reaction center protein complex more effectively and accumulation of phenolic secondary metabolites which could enhance the antioxidant properties and structural integrity of the seed coats may lead to the bleaching resistant phenotype. Therefore, breeding green pea cultivars with higher seed coat antioxidant properties would improve both visual and nutritional quality. This research has provided several insights into molecular approaches to improve field pea visual quality for food markets.
98

Elucidating the genetic basis of bast fibre production in flax (Linum usitatissimum L.)

2012 March 1900 (has links)
Flax is often considered a total utilization crop because of the potential to extract value from two distinct products - seeds and stem fibres. However, very little genetic information is available on flax fibre genetics in comparison to oil improvement studies. In order to gain a detailed understanding of genetic control of the fibre concentration and search for the possibilities of developing dual purpose flax lines using both seed oil and stem fibre, the following studies were initiated: The first study evaluated the fibre and oil-related traits in a recombinant inbred population derived from a cross between a fibre flax variety Viking and an oilseed flax genotype E1747 over multiple locations under western Canadian field conditions. The study confirmed the presence of a significant genotype by environment interaction (p < 0.01) for fibre concentration indicating selection for this trait will be challenging. However, a lack of significant correlation between fibre and oilseed characteristics in field trials was encouraging and strengthened the hypothesis that breeding dual purpose flax types for western Canada is possible. The study also identified potential recombinant inbred lines (RILs) with enhanced fibre concentration as well as oil characteristics for use in future breeding endeavors. The second study established an anatomical basis for further research into flax fibre improvement by studying differences between the stem anatomy of 14 diverse flax genotypes in the field and under controlled environments such as a growth chamber. The results from the study supported the use of controlled environments for the purpose of quick screening of high fibre containing genotypes, especially at the green capsule stage of plant growth. The results also indicated that it was possible to select high fibre oilseed flax lines based on anatomical markers such as average area of single fibre cells, total fibre area and fibre to stem area ratio. In the third study, 17 simple sequence repeat (SSR) and 2 cleaved amplified polymorphic sequences (CAPS) molecular markers were used to assess the extent of genetic variability in the Viking × E1747 RIL population. CAPS markers LuFAD3A and LuFAD3B had the highest marker trait association (p < 0.0001) with linoleic and linolenic acid concentration. SSR markers such as CV8824, 5B6 and LU32 were found to be associated with plant height, oil concentration and protein concentration respectively using single marker analysis and step wise regression analysis. The molecular study confirmed the importance of Viking × E1747 mapping population in identifying genes/ markers related to both fibre and oilseed related traits in flax. In the fourth study, global transcript profiling using cDNA - based microarrays was performed to identify differentially expressed fibre related transcripts between Viking and E1747. The largest group of transcripts (7 %) found more abundant in Viking relative to E1747 fell under the functional group of cell wall development using gene ontology (GO) analysis. Transcripts such as callose synthases, expansins, cytochrome P450, fasciclin-like arabino galactan proteins and β-galactosidases were highly abundant in Viking relative to E1747. The transcripts more abundant in E1747 relative to Viking were UDP – glucose glucosyltransferase, auxin repressed protein, ubiquitin conjugating enzyme, peroxidases and lipid transfer proteins. Quantitative real time PCR results confirmed the suitability of the microarray platform to accurately discriminate transcript profiles between the two diverse flax types. In conclusion, this research has provided a number of new insights into flax fibre genetics. This information lays the foundation for further genetic studies on flax bast fibres and will complement research on developing dual purpose flax varieties.
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Characterization and molecular mapping of drought tolerance in kabuli chickpea (<i>Cicer arietinum L.</i>)

Rehman, Aziz Ur 12 January 2009 (has links)
Abstract Drought is the most common abiotic stress limiting chickpea production in the world. Ninety percent of the worlds chickpea is produced in areas relying upon conserved, receding soil moisture, therefore, crop productivity is largely dependent on efficient utilization of available soil moisture. Because of the variability in drought pattern from year to year, trait based selection could have an advantage over selection on the basis of grain yield alone. Trait based breeding, however, requires trait dissection into components. Successful marker identification would facilitate integration of MAS procedures in breeding programs enabling the pyramiding of favourable alleles.<p> The genetic map produced in this study was based on a population of recombinant inbred lines of a cross of ILC 588 x ILC 3279 containing 52 SSR markers spanned 335 cM of the chickpea genome at an average density of 6.4 cM. A total of 13 genomic regions were shown to be associated with drought tolerance traits. Some of these genomic regions showed pleiotropic effect on multiple traits. This was also supported by the analysis of phenotypic data where these traits were found to be correlated. For example, early flowering and maturity had a strong association with high grain yield. High grain yield was also associated with better portioning ability between biomass and grain yield, i.e. harvest index. Drought tolerance score (DTS) was associated with various important traits including biomass, early flowering, early maturity.<p> This study also concluded that chickpea genotypes differed in terms of root length, root length density, root weight density and root length to weight ratio at every 20 cm soil layer up to 100 cm depth in response to water deficits. Consideration of an efficient root system vs. a larger root system is also important, since in this research, large root systems were offset by low harvest index, presumably due to the lack of assimilate available for grain growth. A restricted root system is important in environments like Western Canada, where crop growth termination is usually required prior to fall frost. This study also reported significant associations of stomatal conductance (gs) with each of HI, grain yield under drought, drought susceptibility index and drought tolerance score (DTS). Stomatal conductance can also be used to assess plant stress due to drought. Values of gs less than 250 mmol m-2s-1 during flowering indicated drought stress under greenhouse conditions. A higher degree of plant stress due to drought was shown by increased stomatal closure at midday (gs <150 mmol m-2s-1). The study of 157 RILs under natural drought stress during 2005-07 revealed that the 17 RILs which had high grain yield under drought (Group A), also tended to have higher gs than the 42 RILs that had lower grain yield (Group B). Group A had mean gs values of 390 mmol m-2s-1 during the week before flowering, while Group B had mean gs value of 330 mmol m-2s-1. Stomatal conductance increased at flowering and then sharply decreased later in the reproductive period, particularly in Group B. These findings were also supported by canopy temperature differential measurements as Group A was also able to maintain lower canopy temperature than Group B, indicating the ability of these plants to maintain adequate transpiration and a cooler canopy under drought stress. This research indicated that gs and canopy temperature can be used to assess chickpea drought stress and to screen drought tolerant genotypes. This study identified a QTL on LG7 for gs, QTLs on LG1, LG3 and LG6 associated with canopy temperature differential, as well as QTLs associated with grain yield under drought, HI, DTS, days to flower, days to maturity, reproductive period and plant height. These QTLs identified for traits related to higher chickpea productivity under drought stress could have important implications for accelerating the process of pyramiding of favourable genes into adapted genotypes and on future marker-assisted breeding for drought prone areas.
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Genetic analysis, QTL mapping and gene expression analysis of key visual quality traits affecting the market value of field pea

Ubayasena, Lasantha Chandana 15 April 2011 (has links)
Visual quality is one of the major factors that determine the market value of field pea (Pisum sativum L.). Breeding for improved visual quality of pea seeds is currently a challenging task, because of the complexity and lack of sound genetic knowledge of the traits. The objectives of this research were to characterize the genetic basis and identify the genomic regions associated with four key visual quality traits (cotyledon bleaching in green pea, greenness in yellow pea, and seed shape and seed dimpling in both green and yellow types) in field pea. Biochemical and gene expression profiling to understand the molecular basis of post-harvest cotyledon bleaching in green pea was also addressed. Two F5:6 recombinant inbred line (RIL) populations (90 lines from Orb X CDC Striker cross, and 120 lines from Alfetta X CDC Bronco cross) were developed and evaluated for visual quality traits in two locations in Saskatchewan, Canada in 2006 and 2007. The four quality traits evaluated all displayed a continuous range of expression with moderate to high heritability. Two genetic linkage maps utilizing 224 markers (29 simple sequence repeat (SSR) (from Agrogene) and 195 amplified fragment length polymorphism (AFLP)) and 223 markers (27 SSR and 196 AFLP ) were constructed for the Orb X CDC Striker population and the Alfetta X CDC Bronco population, respectively. Multiple quantitative traits (QTL) mapping detected major QTLs on linkage group (LG) IV and LG V, as well as location- and year-specific QTLs on LG II and LG III associated with green cotyledon bleaching resistance. Nine QTLs controlling yellow seed lightness, three for yellow seed greenness, 15 for seed shape and nine for seed dimpling were detected. Among them, 5 QTLs located on LG II, LG IV and LG VII were consistent in at least two environments. The QTLs and their associated markers will be useful tools to assist pea breeding programs attempting to pyramid positive alleles for the traits. The bleaching resistant cultivar CDC Striker had a slower rate of chlorophyll degradation in cotyledons and a higher carotenoid to chlorophyll ratio in seed coats than the bleaching susceptible cultivar Orb when seed samples were exposed to high intensity light. An oligo-nucleotide microarray (Ps6kOLI1) was utilized to investigate the gene expression profiles of CDC Striker and Orb seed coats at different developmental stages. It clearly indicated that the expression of genes involved in the production and accumulation of secondary metabolites was significantly different between these cultivars. The results of both biochemical and gene expression studies suggested the bleaching resistance in CDC Striker was not due to the accumulation of chlorophyll pigments in the cotyledons, but rather due to the ability of seed coats to protect them from photooxidation. Accumulation of specific carotenoids which could bind with the reaction center protein complex more effectively and accumulation of phenolic secondary metabolites which could enhance the antioxidant properties and structural integrity of the seed coats may lead to the bleaching resistant phenotype. Therefore, breeding green pea cultivars with higher seed coat antioxidant properties would improve both visual and nutritional quality. This research has provided several insights into molecular approaches to improve field pea visual quality for food markets.

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