<p>Bryophytes, by their haploid dominant life cycle, possess several unique qualities ideal for study of mating patterns. In particular, the possibility of intragametophytic selfing in some species, and the vegetative propagation of gametes allow for a unique window into the haploid stage that is intractable in other groups. Despite these advantages, there have been relatively few studies on mating patterns bryophytes in natural populations. <italic>Sphagnum</italic> (peatmoss) is an excellent case study in the interactions between sexual condition, ecology, and mating patterns. In the first Chapter, we use microsatellites to characterize the genetic diversity and mating patterns in fourteen species of <italic>Sphagnum</italic>, diverse in sexual condition (separate vs combined sexes in the haploid stage) and ecology (microhabitat variance along the water table). We find that genetic diversity and mating patterns are related only in species with separate sexes, that sexual condition and ecology have interacting effects on inbreeding coefficients, and that inbreeding depression is not a common phenomenon in <italic>Sphagnum</italic>. In the second Chapter, we conduct an intensive survey of one population of <italic>Sphagnum</italic> macrophyllum, to detect whether variance in haploid fecundity and mating success is related to diploid fitness. We find a relationship between mating success and fecundity (a signal of sexual selection), and fitness of the diploid generation is connected to the parentage of the haploid generation. Finally, in Chapter 3 we use phylogenetic comparative methods to track the phylogenetic signal in microhabitat preference in <italic>Sphagnum</italic>. We find extremely fast rates of evolution along the micronutrient gradient, but high phylogenetic signal along a hydrological gradient. Given that <italic>Sphagnum</italic> species living high above the water table have reduced water availability, phylogenetic signal in the hydrological gradient has macroevolutionary implications for mating systems in <italic>Sphagnum</italic>.</p> / Dissertation

Salinity is a critical challenge facing productivity of crops around the world, causing major reduction in growth, yield, and quality. It is necessary to produce varieties with the ability to tolerate salinity. However, the lack of genetic variation among H. vulgare genotypes prevents progress in developing salt tolerant varieties. H. bulbosum is a source of tolerance to stress conditions. Consequently, five accessions of domestic barley and six of wild barley were used in this study. Accessions were screened for salinity tolerance. Genotypes 7, 9, and 10 germinated at 2% NaCl. Lines of H. vulgare showed reduction of root and shoot length greater than H. bulbosum. Crosses were made between diploid and tetraploid H. vulgare ♀ and tetraploid H. bulbosum ♂. Immature embryos were rescued. Murashige and Skoog medium was found to be generally better for most crosses. Number of successful crosses varied among families. Female 5, for diploid crosses, and female 2, for tetraploid crosses, have high GCA and compatibility with bulbosum males, and 17.9% and 17.6% of their progeny exceeding the mean grain yield, respectively. Parent 9 had also high GCA and compatibility with vulgare parents (2x), and its progeny seem to exceed the mean in many cases with most families. During germination screening, progeny of diploid females 1 and 2 were found to be highly desirable for saline tolerance. Among the tetraploid crosses, Family 1 had greatest percentage of superior progeny (18.8%), while Families 2 and 3 had greatest number of superior individuals (8 and 7, respectively). For seedling growth, diploid Families 2 and 3 crosses had the greatest shoot dry weight and tolerant saline index (SSI<1). Families 2 and 4 of tetraploid crosses had 12 of 39 and eight of 26 crosses show greatest shoot dry weight and tolerance as measured by SSI, respectively. Final germination percentage (FG%) showed positive association with plant height, while associating negatively with tiller number, fertility, cSW, and grain yield. In diploid crosses, FG% associated positively with tiller number. Shoot dry weight showed negative association with plant height, while it associated positively with tiller number, fertility, cSW, and grain yield.

A produção de linhagens completamente homozigotas em programas de melhoramento genético de citros é difícil e demorada, e a obtenção de plantas duplo-haplóides pode ser utilizada para aumentar a eficiência de programas de melhoramento. No entanto, muitos são os fatores associados ao sucesso na regeneração de plantas haploides e/ou duplo-haplóides. Os objetivos deste projeto foram a obtenção de plantas haploides e/ou duplo-haplóides de laranja doce (Citrus sinensis) utilizando as técnicas de cultura de anteras e partenogênese in situ e in vitro, que consistem na obtenção e regeneração de embriões gaméticos a partir do desenvolvimento dos micrósporos e óvulos, respectivamente. Para tal, foram realizados estudos preliminares de biologia reprodutiva de C. sinensis, bem como a realização de trabalhos de cultura de anteras de laranja-doce, foram conduzidos testando-se aproximadamente 100 genótipos, além dos efeitos de tratamentos térmicos aplicados as anteras de laranja doce. Para os experimentos de partenogênese in situ foram testados os efeitos das doses de radiação aplicadas aos grãos de polens utilizados para a polinização e do uso de pólens de espécies consideradas distantes na obtenção de embriões e plantas haploides e duplo-haplóides de C. sinensis. Para a partenogênese in vitro foram testados os efeitos de meios de cultura na indução de embriogênese a partir de calos provenientes dos ovários. Os resultados obtidos permitiram a indução de calos, calos embriogênicos, e a regeneração de embriões a partir do cultivo in vitro de anteras. Também foi possível a seleção de genótipos mais responsivos a essa técnica e que permitirão a realização de trabalhos futuros para o processo de obtenção de plantas haploides e duplo-haplóides em laranja doce. Na maioria dos casos, os calos embriogênicos, embriões e plântulas obtidas da cultura de anteras foram diploides (2n) e molecularmente similares às plantas doadoras dos explantes. No entanto, houve a obtenção de um calo embriogênico, proveniente do cultivo de anteras de um híbrido (Citrus clementina x C. sinensis ,,Hamlin\"), que até o momento demonstrou um padrão de bandamento diferente e em homozigose para quatro conjuntos de primers microssatélites testados. A confirmação da ploidia e da origem gamética desse calo ainda é dependente da realização de análises com os embriões provenientes desses calos e de um maior número de marcadores moleculares. Nos experimentos de partenogênese in situ foram obtidos embriões e plântulas provenientes da polinização com polens irradiados, sendo identificadas plântulas com grande variação no nível de ploidia e com diferenças moleculares entre as progênies e os parentais, porém heterozigotas. A realização de cruzamentos com espécies distantes permitiram a obtenção de embriões e plântulas que apresentavam alta taxa de genes em homozigose, porém não em sua totalidade. Nas técnicas de partenogênese in vitro foi possível a obtenção de um protocolo para regeneração de embriões somáticos a partir de calos de ovários, no entanto, também não foram observadas a obtenção de plantas haploides e/ou duplo-haplóides. Os resultados obtidos confirmam a genótipo-dependência das respostas relacionadas à embriogênese gamética em Citrus, bem como do melhor entendimento dos aspectos reprodutivos de laranja doce / The production of completely homozygous lines in citrus breeding program is hard, and double-haploid plantlets (completely homozygous lines) can be used to improve these breeding programs. However, many factors are associated with the success of the regeneration of haploid or double-haploid plants. The aim of this study was the induction and regeneration of haploid and double-haploid plantlets from sweet oranges (Citrus sinensis) using the techniques of anther culture and in situ and in vitro parthenogenesis, that can result in the production of gametic embryos from microspores and ovules, respectively. To this, there were conducted preliminary studies with reproductive biology of C. sinensis, as well as, experiments with anther culture of more than 100 genotypes of sweet orange and the effects temperature treatments. To experiments of in situ parthenogenesis there were tested the effects of genotype, doses of radiation applied to the pollen grains, and also the use of pollen grains from distant species used in crossings with the aim of obtaining haploid and double-haploid embryos from sweet oranges. To in vitro parthenogenesis there was tested the effects of culture media in induction of embryogenesis from ovaries. The results showed the induction of callus and regeneration of embryos from in vitro anther culture and obtaining some responsive genotypes to anther culture, which will be useful in future works with induction and regeneration of haploid and double-haploid plants in sweet orange. The most of embryogenic callus and embryos obtained from anther culture were diploids (2n) and molecularly similar to the donor plants. However, one embryogenic callus obtained from anther culture of a hybrid (Citrus clementina x C. sinensis ,,Hamlin\") showed be different from donor plants and homozygous to four pair of microsatellite primers tested. Ploidy and the gametic origin confirmation of this embryogenic callus are still dependent of the analysis of a larger number of primers and the development and regeneration of embryos. In the in situ parthenogenesis experiments, the embryos and seedlings obtained from the pollination with irradiated pollen grains showed a larger variation of ploidy, determined by flow cytometric analysis. The analysis with molecular markers showed that these plantlets were different from the donor plants, but were heterozygous. The performance of crossings with distant species from Citrus sinensis results in production of embryos with a high rate of homozygosis, but not for all primers tested. In vitro parthenogenesis techniques shows be interesting to obtaining somatic embryos from ovary culture, however, no haploid or double-haploid embryos were obtained. The results confirm the genotype-dependent responses related to the gametic embryogenesis in Citrus, as well as, improve the knowledge about reproductive biology of sweet orange

A produção de linhagens completamente homozigotas em programas de melhoramento genético de citros é difícil e demorada, e a obtenção de plantas duplo-haplóides pode ser utilizada para aumentar a eficiência de programas de melhoramento. No entanto, muitos são os fatores associados ao sucesso na regeneração de plantas haploides e/ou duplo-haplóides. Os objetivos deste projeto foram a obtenção de plantas haploides e/ou duplo-haplóides de laranja doce (Citrus sinensis) utilizando as técnicas de cultura de anteras e partenogênese in situ e in vitro, que consistem na obtenção e regeneração de embriões gaméticos a partir do desenvolvimento dos micrósporos e óvulos, respectivamente. Para tal, foram realizados estudos preliminares de biologia reprodutiva de C. sinensis, bem como a realização de trabalhos de cultura de anteras de laranja-doce, foram conduzidos testando-se aproximadamente 100 genótipos, além dos efeitos de tratamentos térmicos aplicados as anteras de laranja doce. Para os experimentos de partenogênese in situ foram testados os efeitos das doses de radiação aplicadas aos grãos de polens utilizados para a polinização e do uso de pólens de espécies consideradas distantes na obtenção de embriões e plantas haploides e duplo-haplóides de C. sinensis. Para a partenogênese in vitro foram testados os efeitos de meios de cultura na indução de embriogênese a partir de calos provenientes dos ovários. Os resultados obtidos permitiram a indução de calos, calos embriogênicos, e a regeneração de embriões a partir do cultivo in vitro de anteras. Também foi possível a seleção de genótipos mais responsivos a essa técnica e que permitirão a realização de trabalhos futuros para o processo de obtenção de plantas haploides e duplo-haplóides em laranja doce. Na maioria dos casos, os calos embriogênicos, embriões e plântulas obtidas da cultura de anteras foram diploides (2n) e molecularmente similares às plantas doadoras dos explantes. No entanto, houve a obtenção de um calo embriogênico, proveniente do cultivo de anteras de um híbrido (Citrus clementina x C. sinensis ,,Hamlin\"), que até o momento demonstrou um padrão de bandamento diferente e em homozigose para quatro conjuntos de primers microssatélites testados. A confirmação da ploidia e da origem gamética desse calo ainda é dependente da realização de análises com os embriões provenientes desses calos e de um maior número de marcadores moleculares. Nos experimentos de partenogênese in situ foram obtidos embriões e plântulas provenientes da polinização com polens irradiados, sendo identificadas plântulas com grande variação no nível de ploidia e com diferenças moleculares entre as progênies e os parentais, porém heterozigotas. A realização de cruzamentos com espécies distantes permitiram a obtenção de embriões e plântulas que apresentavam alta taxa de genes em homozigose, porém não em sua totalidade. Nas técnicas de partenogênese in vitro foi possível a obtenção de um protocolo para regeneração de embriões somáticos a partir de calos de ovários, no entanto, também não foram observadas a obtenção de plantas haploides e/ou duplo-haplóides. Os resultados obtidos confirmam a genótipo-dependência das respostas relacionadas à embriogênese gamética em Citrus, bem como do melhor entendimento dos aspectos reprodutivos de laranja doce / The production of completely homozygous lines in citrus breeding program is hard, and double-haploid plantlets (completely homozygous lines) can be used to improve these breeding programs. However, many factors are associated with the success of the regeneration of haploid or double-haploid plants. The aim of this study was the induction and regeneration of haploid and double-haploid plantlets from sweet oranges (Citrus sinensis) using the techniques of anther culture and in situ and in vitro parthenogenesis, that can result in the production of gametic embryos from microspores and ovules, respectively. To this, there were conducted preliminary studies with reproductive biology of C. sinensis, as well as, experiments with anther culture of more than 100 genotypes of sweet orange and the effects temperature treatments. To experiments of in situ parthenogenesis there were tested the effects of genotype, doses of radiation applied to the pollen grains, and also the use of pollen grains from distant species used in crossings with the aim of obtaining haploid and double-haploid embryos from sweet oranges. To in vitro parthenogenesis there was tested the effects of culture media in induction of embryogenesis from ovaries. The results showed the induction of callus and regeneration of embryos from in vitro anther culture and obtaining some responsive genotypes to anther culture, which will be useful in future works with induction and regeneration of haploid and double-haploid plants in sweet orange. The most of embryogenic callus and embryos obtained from anther culture were diploids (2n) and molecularly similar to the donor plants. However, one embryogenic callus obtained from anther culture of a hybrid (Citrus clementina x C. sinensis ,,Hamlin\") showed be different from donor plants and homozygous to four pair of microsatellite primers tested. Ploidy and the gametic origin confirmation of this embryogenic callus are still dependent of the analysis of a larger number of primers and the development and regeneration of embryos. In the in situ parthenogenesis experiments, the embryos and seedlings obtained from the pollination with irradiated pollen grains showed a larger variation of ploidy, determined by flow cytometric analysis. The analysis with molecular markers showed that these plantlets were different from the donor plants, but were heterozygous. The performance of crossings with distant species from Citrus sinensis results in production of embryos with a high rate of homozygosis, but not for all primers tested. In vitro parthenogenesis techniques shows be interesting to obtaining somatic embryos from ovary culture, however, no haploid or double-haploid embryos were obtained. The results confirm the genotype-dependent responses related to the gametic embryogenesis in Citrus, as well as, improve the knowledge about reproductive biology of sweet orange

Identification of allelic variation through quantitative trait loci (QTL) mapping offers possibilities for the improvement of quantitatively inherited traits. This requires a genetic map along with the phenotypic characterization of a mapping population. A doubled haploid (DH) Polo X Topas population consisting of 194 lines and a recombinant inbred line population of 92 lines was developed. Individual genetic maps derived from each population were integrated into a consensus map. The DH-based genetic map was used for QTL mapping. The DH-based map was comprised of 620 loci that were assembled into 19 linkage groups that were anchored to the B. napus chromosomes. The DH-based map covered 2244.1 cM genomic distance with an average marker interval of 3.7 cM. The DH population was phenotyped in four environments with each line replicated twice in a randomized complete block design. Days to flowering was recorded and oil content and fatty acid composition were determined using Near Infrared spectroscopy (NIR) and Gas Chromatography, respectively. Fourteen QTL were identified for oil content, 33 QTL for palmitic acid content, 18 QTL for stearic acid content, 21 QTL for oleic acid content, 20 QTL for linoleic acid content, 23 QTL for linolenic acid content, 16 QTL for arachidic acid content and 14 QTL for flowering time. Oil content QTL were identified on five linkage groups, A3, A10, C1, C5, and C6. An oil content QTL, qOIL-A10c appeared in all four environments, whereas qOIL-A10a appeared in only one environment but explained 26.99% variation. The oil content in the population ranged from 35% to 55.5% with the parents having values of 42% to 46%. Two genomic regions on C3, with map positions at 147.83 cM and 154.55 cM harbored QTL (rQTL) for all the fatty acids studied. The additive effects of the rQTL reveal a correlation pattern which is supported by the phenotypic correlation observed between the fatty acids. This suggests rQTL have role in the fatty acid composition and possibly determine total seed oil content. The rQTL and flanking markers of the identified QTL offer utility in further development of B. napus. / October 2015

Genes novos, definidos como aqueles presentes em um grupo ou espécie mas ausentes em seu grupo irmão e grupo externo, são conhecidos por terem mais marcadores de seleção positiva que genes antigos. Sabe-se também que a seleção positiva ocorre de forma mais rápida em sistemas haplóides do que em sistemas diplóides. Aqui unimos esses dois sistemas para propor um modelo de seleção haplóide de genes novos. Para isso utilizamos dados de expressão, idade evolutiva, e assinatura de seleção provenientes de genes de Drosophila melanogaster. Mostramos que genes novos adquirem uma vantagem seletiva se expressos nas fases tardias da espermatogênese, que são haplóides. Não só há mais genes novos com alta expressão nas fases haplóides (meiótica e pós-meiótica) da espermatogênese em relação à fase diplóide (mitótica), mas também os genes novos possuem expressão mais acentuada que genes antigos nessas fases haplóides. Mostramos que os genes com alta expressão nas fases haplóides possuem mais marcadores de seleção positiva, e.g. valores de dN/dS, alpha e para outros modelos que estimam seleção positiva. Dessa forma, propomos um modelo que explica a maior expressão de genes novos nos testículos (fases haplóides da espermatogênese) e como tais genes se fixam na espécie. Por fim, explicamos a maior incidência de genes extremamente novos ligados ao X e com expressão preferencial em machos. Isso ocorre por que genes ligados ao cromossomo X em machos tem expressão funcionalmente haplóide, visto que o X está em hemizigose em todas as células somáticas de machos. Essa situação torna benéfico para genes muito novos ligados ao X que sua seleção em machos ocorra, pois em todas as células tais genes tem o benefício da seleção haplóide. Em particular, genes extremamente novos, ao contrário de genes antigos, do cromossomo X são capazes de burlar a inativação do cromossomo sexual durante a meiose. Isso os torna um bom sistema para novos alelos recessivos e com antagonismo sexual serem expressos e selecionados / New genes, those present in one group or species but absent in their sister group and outgroup, are frequently under positive selection, as shown by their higher rates and values of positive selection markers. It is also known that beneficial genes in haploid systems tend to be fixed more quickly than in diploid ones. Here we propose to merge this two systems by proposing a model for new genes selection in haploid systems. To do so we use Drosophila melanogaster\'s spermatogenesis process. We show that new genes have a selective advantage if they are expressed in the haploid (meiotic and post-meiotic) phases of spermatogenesis. This is shown not only by the greater proportion of new genes with high expression in those phases against the diploid (mitotic) phase, but also by the intensity of the expression of new genes being greater than that of old genes during the haploid phases. We also show that genes with higher expression in the haploid phases present more markers of positive selection. They have both a greater value of dN/dS, alpha and a greater proportion of genes that best fit a model with selection than one without it. Therefore, we propose a model explaining the higher expression of new genes in the testis (haploid phases of spermatogenesis) and how those genes become fixed in the population and species. At last we explain the abundance of new male-biased genes on the X. This enrichement is due to the functionally haploid expression of the X-linked genes in males. This assures an advantage to those genes, as they will benefit from haploid selection system in the X on males. It is then beneficial for X-linked genes to be selected uppon in the males, as it will resemble haploid selection. Also, extremely new X-linked genes, as opposed to old ones, can bypass the sex cromosome inactivation, being a good system for new antagonistic recessive alleles to be expressed and sellected upon

Dentre as diversas questões envolvendo a tecnologia duplo haploides (DH) em milho, uma que tem sido pouco discutida é a geração em que se deve induzir haploides, no caso, F1 ou F2. Destas, a F1 tem sido a mais utilizada. No entanto, o seu uso constante pode levar a perdas de ganhos genéticos, devido ao menor número de recombinações. Com isso, alguns autores aconselham o uso da F2 na indução, o que possibilitaria maiores ganhos em variabilidade genética. Desse modo, os objetivos foram verificar o efeito das gerações F1 e F2 na expressão do R1-navajo em germoplasma tropical, na eficiência relativa de cada uma das etapas da metodologia e na variabilidade genética das linhagens DH obtidas. Para isso, cinco fontes de germoplasma, em gerações F1 e F2, foram cruzadas com o indutor de haploidia tropicalizado LI-ESALQ. As sementes deste cruzamento foram agrupadas por meio do marcador R1-navajo em três classes: haploides putativos, diploides e inibidas. Após esta etapa, as sementes dos haploides putativos foram submetidas à duplicação cromossômica e as plantas duplicadas foram transplantadas a campo para a obtenção de linhagens DH. As unidades de sementes, plântulas e plantas em cada etapa da metodologia foram quantificadas para o estudo da eficiência relativa na obtenção de DH. Também foram coletadas amostras foliares das linhagens DH para genotipagem por meio de marcadores SNP (Single nucleotide polymorphism). As taxas de indução de haploides (HIR), sementes diploides (DSR) e inibidas (ISR) foram analisadas por meio de um modelo linear generalizado misto considerando distribuição logit multinomial. As eficiências relativas das fontes de germoplasma e gerações em cada etapa da metodologia DH foram estimadas por meio de porcentagem. Os marcadores SNP foram utilizados em estudos de diversidade genética, estrutura populacional e desequilíbrio de ligação. Os valores médios observados para as taxas de HIR, ISR e DSR foram, respectivamente, 1,23%, 23,4% e 75,2% para a geração F1 e 1,78%, 19,6% e 82,3% para a geração F2. O maior valor de HIR na F2 ocorreu devido à segregação dos genes que inibem o marcador R1-navajo durante a indução de haploides. Entretanto, apesar da geração F2 apresentar maior HIR, ela não deve substituir a F1, uma vez que se perde tempo com um ciclo adicional. A eficiência relativa na obtenção de linhagens DH apresentou o mesmo valor (0,4%) para as gerações F1 e F2, indicando que a escolha da geração não interfere na quantidade de DH produzidos. As estimativas dos parâmetros populacionais para as linhagens DH obtidas de geração F1 apresentaram valores para variância genética (VG) de 700,55, tamanho efetivo populacional (Ne) de 43,1, diversidade genética de Nei (GD) de 0,28 e conteúdo de informação polimórfica (PIC) de 0,23. Para a geração F2 as estimativas foram de VG=648,88, Ne=39,61, GD=0,26 e PIC=0,22. Os valores de desequilíbrio de ligação foram de 0,069 na geração F1 e de 0,067 na geração F2. Ou seja, as linhagens DH oriundas destas duas gerações apresentaram magnitudes semelhantes de diversidade genética e de desequilíbrio de ligação. O uso da geração F2 teoricamente permitiria obter maior variabilidade genética, devido à recombinação adicional. Entretanto, neste trabalho esta tendência não foi observada. Com isto, em milho tropical, recomenda-se o uso da geração F1 para a obtenção de DH, por apresentar o melhor balanço entre tempo e variabilidade genética. / Among the several questions involving doubled haploid technology (DH), one that has been little discussed is the generation in which one should induce haploids, in the F1 or F2. Overall, the F1 generation has been the most used. However, their constant use can lead to losses of genetic gains with the selection cycles due to the lower number of recombination. Thereby, some authors advise the use of F2 in inductions, which would allow greater gains in genetic variability. Thus, the objectives were to check the effect of the F1 and F2 generations on the expression of the R1-navajo in tropical germplasm, on the relative efficiency of each step of the methodology and the genetic variability of the DH lines obtained. For this purpose, five germplasm sources, in F1 and F2 generations, were crossed with the tropicalized haploid inducer LI-ESALQ. The seeds from this cross were grouped using the R1-navajo marker into three classes: putative haploids, diploid and inhibited. Then, putative haploid seeds were submitted to chromosome duplication, and the duplicate seedlings were transplanted to the field in order to obtain DH lines. Hence, seed, seedling, and plant at each stage of the methodology were quantified to study the relative efficiency in developing DH lines. Moreover, leaf samples from the D0 lines were collected for genotyping using SNP (Single nucleotide polymorphism) markers. Finally, the haploid inducer rate (HIR), diploid seed rate (DSR) and inhibited seed rate (ISR) were analyzed using a generalized linear mixed model considering multinomial logit distribution. The relative efficiency of germplasm sources and generation in each stage of the DH methodology was estimated by percentage. SNP markers were used in studies of genetic diversity, population structure, and linkage disequilibrium. The observed mean values of HIR, ISR and DSR were, respectively, 1.23%, 23.4% and 75.2% for the F1 generation and 1.78%, 19.6% and 82.3% for the F2 generation. The higher value of HIR in F2 occurred due to the segregation of genes, which inhibit the R1-navajo marker during haploid induction. However, in spite of the higher value of HIR for F2 generation, it should not replace F1 since time is lost with an additional cycle. The relative efficiency observed in the obtention of DH lines was the same value (0.4%) for generations F1 and F2, indicating that the choice between those generations does not interfere with the quantity of produced DH. Estimates of the population parameters for the DH lines obtained from F1 generation presented values for genetic variance (VG) of 700.55, effective population size (Ne) of 43.1, Nei\'s genetic diversity (DG) of 0.28 and polymorphic information content (PIC) of 0.23. For F2 generation the estimates were VG = 648.88, Ne = 39.61, GD = 0.26 and PIC = 0.22. Linkage disequilibrium values were 0.069 in the F1 generation and 0.067 in the F2 generation. Thus, DH lines from these two generations showed similar values of genetic diversity and linkage disequilibrium. Nonetheless, the use of the F2 generation theoretically would allow obtaining greater genetic variability, due to the additional cycle of crossing-overs. However, this trend was not observed in this study. Thus, in tropical maize, the use of the F1 generation to obtain DH lines is recommended, because it performs the best balance between time and genetic variability.

O milho é uma espécie alógama cujo produto comercial são os híbridos, os quais originam-se do cruzamento de duas linhagens endogâmicas. Uma forma para obtenção de tais linhagens é por meio das técnicas de indução de haploidia e posterior obtenção dos duplo-haploides, permitindo até 100% de homozigose. Essas técnicas retornam resultados importantes no melhoramento de milho. Uma variável de interesse importante, obtida a partir dessas técnicas é a taxa de indução de haploidia, a qual trata-se de uma proporção entre o número de sementes haploides e o número total de sementes. O conjunto de dados foi obtido pelo cruzamento da linhagem indutora LI- ESALQ, com cinco genótipos comerciais de milho (2B587PW, 30F53H, BM820, DKB390 e STATUS VIPTERA), em duas gerações F1 e F2, por meio de um delineamento em blocos ao acaso, na área experimental do Departamento de Genética da ESALQ/USP. A teoria dos modelos lineares generalizados (MLGs) possibilita mais opções para a distribuição da variável resposta, exigindo somente que a mesma pertença à família exponencial sob a forma canônica. Tal classe de distribuições pode ser ainda expandida para modelos que permitem efeitos aleatórios no preditor linear, caracterizando a classe dos modelos lineares generalizados mistos (MLGMs). O objetivo deste trabalho foi analisar a taxa de indução de haploidia em milho tropical, utilizando um modelo binomial misto, com efeito aleatório em nível de indivíduo. O método de estimação foi o de máxima verossimilhança. Com base em tal modelagem, verificou-se que o genótipo 30F53H, destacou-se em relação aos demais quanto à eficiência da taxa de indução de haploidia. Todas as análises foram implementadas no software R. / The maize is an allogeneic species whose commercial product are the hybrids, which are gerated by the crossing of two endogenous lines. An alternative to obtain these lines is using the haploid induction techniques and subsequent doubled haploid production, that allows up to 100% homozygous. Artificial production of doubled haploids is important in plant breeding. An important variable, that results from these techniques, is the haploid induction rate, which is a proportion between the number of haploid seeds and the total number of seeds. The data set was obtained by crossing the inductive line LI-ESALQ, with five commercial genotypes of corn (2B587PW, 30F53H, BM820, DKB390 and STATUS VIPTERA), in two generations F1 e F2, in a randomized block design, in the experimental area of Department of Genetics, ESALQ/USP. The generalized linear models (GLMs) allow more options for the variable response distribution, requiring only that it belongs to the exponential family in canonical form. The GLM class can be expanded to models that allow random effects in the linear predictor, the mixed generalized linear models (MGLM) class. This work aimed to analyze the haploid induction rate in the tropical maize. The binomial mixed model, that included random effects in individual level, was proposed. The maximum likelihood method was used to estimate the parameters. The result revealed that the genotype 30F53H stands out in relation to the others regarding the efficiency in the haploid induction rate. All the analyzes were implemented in the software R.

Peculiarities of edible onions (Allium cepa L.) gynogenesis investigated in the dissertation work. Conditions for creation of dihaploid plants evaluated. Biological assumptions for preparation of methodical suggestions, that would enable improving of gynogenesis, determined. Stimulation effect of using TDZ and NAR in media on the formation of edible onion embryogenic tissue has been revealed for the first time. Characteristic higher frequency of gynogenesis of unfertilized flower of edible onion isolated from the flower stems soaked in 2,4-D solution has been evaluated. By using experimental method it has been established that 3 day length gynogenesis induction period, using media containing 2,4-D and BA, is enough to induce gynogenesis of edible onion. High heterogeneity of edible onion variety population ‘Lietuvos didieji’ has been demonstrated from the point of organogenesis in isolated unfertilized flower culture. It has been established that the efficiency of edible onion gynogenesis can be increased by decreasing plant donor growing temperature in the final phases of flower development and using of exogenous growth regulators TDZ and NAA in plant regeneration media as well as by flower stems soaking in 2,4-D solution for 14 days. Plants with characteristic high gynogenesis frequency have been determined according to evaluation of edible onion variety population ‘Lietuvos didieji’ organogenetic response. 10 homozygous lines of edible onion have been created. 2 lines with... [to full text]

Fusarium head blight (FHB), a fungal disease caused principally by Fusarium graminearum, and barley yellow dwarf (BYD) caused by BYD luteoviruses are two serious fungal and viral diseases of wheat resulting in high economic losses annually. Wuhan, a Chinese wheat cultivar resistant to FHB, and Maringa, a Brazilian cultivar tolerant to BYDV were inter-crossed and crossed with Roblin, a Canada western red spring wheat susceptible to both FHB and BYDV, to determine the genetic basis of resistance/tolerance and to combine the two traits. Four hundred ninety nine F1-derived doubled haploid (DH) lines were generated from reciprocal crosses using corn pollen-mediated DH technology. The DH lines and the parents were evaluated for disease symptoms, reduction in height and spike mass for BYD and for disease incidence, disease severity and Fusarium-damaged kernels for FHB in field and controlled environments. A subset (20/150) of the best performing DH lines from Wuhan/Maringa populations for both BYD and FHB were further evaluated. Plants were point inoculated with F. graminearum in greenhouse experiments, and macroconidial spray inoculations and spread of corn inoculum were used in field environments to evaluate FHB. BYDV inoculations were performed by placing ten to fifteen viruliferous aphids (Rhopalosiphum padi infected with BYDV-PAV isolate 9301PAV), at the one to two leaf stage for both greenhouse and field trials. The studies showed that both FHB and BYDV are quantitatively inherited. Transgressive segregants were observed and the broad sense heritability was high (0.90 to 0.97) for all traits evaluated. Results from independent testing of diseases on Wuhan/ Maringa populations showed fourteen DH lines were as, or more resistant than Wuhan for FHB and Maringa for BYDV tolerance and have combined both BYDV tolerance and FHB resistance. Identifying such lines facilitates the pyramiding of independent genes to obtain adequate levels of enduring resistance. A further experiment was conducted on the 14 lines by inoculating them with BYDV and F. graminearum successively on the same plant. Six out of 14 selected DH lines demonstrated high resistance to FHB and tolerance to BYDV. These six lines can be used in FHB/BYDV resistance/tolerance breeding programs.