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.

Annual ryegrass (Lolium multiflorum Lam.) can be divided into two cytotypes: diploid (2n = 2x = 14) or tetraploid (2n = 4x = 28). Transforming annual ryegrass from diploid to tetraploid often results in increased seedling vigor, more robust growth and, thus, supposedly greater yield. There has been conflicting research that suggests no difference in yield between diploid and tetraploid cultivars, but livestock producers’ question whether benefits exist to utilizing tetraploid cultivars for grazing cattle. This study sought to determine if annual ryegrass cytotype affected cattle average daily gain. Although there were no differences in average daily gain between cytotypes, there were differences among cultivars. In 2017, Jumbo (4x) produced the greatest weight gain, while in 2018, Tam-90 (2x) generated the greatest gain. This study suggests that there are no advantages attributed to average daily gain by utilizing tetraploid, as opposed to diploid cultivars.

In most plant species artificial polyploidy generally enhances the vigor of determinate plant parts and may be favorable where vegetative organs and biomass constitute the economic product. Furthermore, artificial polyploidy has been considered a method of increasing production potential of plants secondary metabolites. However, despite considerable research on polyploid plants, very few cases of polyploid medicinal plants have been reported. Artemisia annua L. synthesizes artemisinin, an antimalarial sesquiterpene lactone. Artemisinin can be synthesized, but it is costly compared to the naturally derived product. Hairy root cultures of Artemisia annua L. (clone YUT16) show rapid growth and produce artemisinin. This culture offers a good model system for studying artemisinin production. Others have shown that tetraploid Artemisia annua L. plants produce more artemisinin/mg DW than diploids. These yields were offset, however, by decreases in biomass productivity. Little is known about how polyploidy may affect growth production of hairy roots. Using colchicine, we have produced four stable tetraploid clones of Artemisia annua L. from YUT16 hairy root clone. Compared to the diploid clone, these tetraploid clones showed major differences in growth and development. Nevertheless, artemisinin yields of these tetraploid clones were 2-5 times higher than the diploid and their production seemed to be by the age of the inoculum. This work will prove useful in furthering our understanding of the effects of artificial polyploidy on the growth and secondary metabolite production of hairy roots.

Some aspects of the presence of systemic endophytic fungi in agriculturally important New Zealand grasses were studied in relation to plant breeding. Seedling resistance to adult Argentine stem weevil feeding in perennial ryegrass, Italian ryegrass and tall fescue was found to be related to the presence of their respective Acremonium endophytes in the seed rather than to plant genetic resistance. In addition a study of perennial ryegrass revealed that this resistance was independent of endophyte viability. The seedling resistance conferred by the endophyte of Italian ryegrass was found to be beneficial for field establishment. This endophyte differs from that in perennial ryegrass and tall fescue in that it does not confer resistance to Argentine stem weevil on mature plants, but only on seedlings. The extent of plant genetic seedling tolerance to adult Argentine stem weevil feeding was limited to broad inter-specific differences, with tall fescue more tolerant than perennial ryegrass and both of these more tolerant than Italian ryegrass. This ranking corresponds with previous observations on feeding preference on mature plants. A study of factors affecting the concentration of endophyte mycelia in infected seed of perennial ryegrass revealed that plant genetic factors had little effect. The major factors studied were: 1) the endophyte concentration in the maternal parent plant directly influenced the endophyte concentration in the seed. 2) nitrogen fertilizer applications to a seed crop reduced the concentration of mycelia in the seed, with earlier applications having a greater effect. 3) application of the fungicide propiconazole (Tilt) to a seed crop reduced the endophyte concentration in the seed. 4) the endophyte concentration in the seed was found to directly influence the endophyte concentration in seedlings, six month old plants and that of seed harvested from a first year seed crop. As there have been no previous reports of tetraploid perennial ryegrass cultivars with endophyte an experiment was conducted to determine if these could be developed by the standard procedure of colchicine treatment. The results revealed that endophyte was retained following colchicine treatment.

The development of mouse (Mus musculus) haploid parthenogenetic embryos does not reach the same level as normal embryos. The aim of this diploma thesis was to find out whether haploid parthenogenetic embryos of mice differ in the nucleocytoplasmic ratio. The volume of the nucleus increases with ploidity. The nucleocytoplasmic ratios of haploid embryos do not significantly change between the two-cell and four-cell stage (p = 0.052), there is a significant difference (p < 0.001) for diploid and tetraploid embryos. Non-standard nucleocytoplasmic ratio could be related to the problematic development. Understanding the regulation of preimplantational development of parthenogenetic embryos will increase the efficiency of haploid embryonic stem cell derivation.

Fairway crested wheatgrass, which is identified taxonomically as Agropyron cristatum (L . ) Gaertn. (45 ), A. cristatiforme (38) , or A. pectiniforme Roem. and Schult (22), is an economically important range grass belonging to the "crested wheatgrass complex" (24, 38). The crested wheatgrass complex includes diploid, 2n = 14, tetraploid, 2n = 28, and hexaploid, 2n = 42, forms (1, 11, 22). The variety Fairway and Fairway-like derivatives are the only known diploid members of the species complex (24, 38). Meiotic chromosome behavior of Fairway diploids appears to be typical of other diploid species; however, the number of plants examined cytologically has been relatively small. Although Fairway crested wheatgrass is a good seed producer, interplant variation in fertility is high (13, 22, 25, 42). Irregular chromosome behavior is a common source of sterility and may be contributing to the variable seed set in diploid crested wheatgrass. No information is available concerning the relation of meiotic chromosome behavior to fertility in Fairway crested wheatgrass. Polyploid crested wheatgrasses are generally considered to be of autoploid origin, i.e., they are derived by duplication of the chromosome complement of a diploid prototype. Chromosome pairing in the polyploid species (31), in interspecific hybrids (12), and in polyhaploid plants (11) substantiate the autoploid derivation of polyploid crested wheatgrass. Diploid and tetraploid forms of crested wheatgrass have been hybridized by Knowles (24), and chromosome pairing in the hybrids suggest a close relation between the diploid and tetraploid genomes. Colchicine-induced tetraploids of Fairway crested wheatgrass have been produced by Knowles, 1 and these artificial tetraploids are currently being utilized in his crested wheatgrass breeding program. If the full breeding and cytogenetic potentials of diploid crested wheatgrass are to be realized, the meiotic chromosome behavior and the cytotaxonomic status of this species must be fully understood. The present investigation was designed to provide further information concerning the cytogenetic characteristics of Fairway crested wheatgrass and its autotetraploid derivatives. This investigation was established with the following objectives: 1. To examine meiotic chromosome behavior of Fairway crested wheatgrass. 2. To determine the relation of meiotic chromosome behavior to fertility in Fairway crested wheatgrass. 3. To evaluate the effectiveness of several colchicine treatments in doubling the chromosome complement of Fairway crested wheatgrass. 4. To determine the effect of induced polyploidy on plant morphology in colchicine-induced tetraploids of Fairway crested wheatgrass. 5. To determine the meiotic chromosome behavior and fertility of induced tetraploids of Fairway crested wheatgrass.

Perennial warm-season grasses constitute the backbone of many forage production systems, whether for grazing or harvested feed. North American native plants, specifically grasses, forbs and legumes offer unique ecosystem benefits along with forage quality and digestibility that are unmatched by introduced species. The disparity in breeding and research focused on improvement of introduced species as opposed to native genera has led to inflated use of introduced species as forage types in lieu of native options, due to their unimproved nature. Eastern gamagrass [Tripsacum dactyloides (L.) L.] is proven to be a widely adapted, highly productive forage species in the southeast, Great Plains and northeast United States. A major limitation to more widespread use of eastern gamagrass is high seed dormancy, which leads to increased seed cost. Here, research used recurrent phenotypic selection breeding methods to reduce seed dormancy, with the ultimate goal of developing a population of individuals that produce non-dormant eastern gamagrass seed.

The genus Chenopodium contains many economically important species in the New World, but is relatively understudied and poorly understood, especially in terms of evolutionary relationships. A better understanding of the structure of this genus could significantly help in breeding efforts on its cultivated members, notably the tetraploid C. quinoa and also certain varieties of C. berlandieri, also tetraploid. Of special concern is determining which diploid weed species are the most likely ancestors for C. quinoa, C. berlandieri, and the other tetraploid members of subsection Cellulata. The phylogeny can be understood in part by examining the ribosomal RNA loci and observing how many copies of the 5S and 45S loci each New World species contains. In this work, the 5S and 45S ribosomal RNA loci are characterized by means of fluorescence in situ hybridization in 23 Chenopodium species collected in the New World, with the 5S locus labeled red and the 45S locus labeled green. Based on these results, the pool of most likely candidate ancestor species for C. quinoa and C. berlandieri includes C. fremontii, C. incanum, C. neomexicanum, and C. watsonii.

Whole genome duplication, or polyploidy, is a common process in plants by which failures in meiosis or fertilization result in offspring with twice the number of chromosomes. This doubles the number of copies of every gene, an effect thought to generate new ‘raw material' upon which natural selection can act. Few studies exist examining the consequences of polyploidy for plant physiological traits. Doubling the number of gene copies may have unknown effects on leaf structure and function. In this study, I compare diploid, tetraploid, and hexaploid species within the genus Helianthus (wild sunflowers). Forty different accessions of wild sunflowers were grown under standardized greenhouse conditions and phenotyped for both leaf functional traits and leaf hyperspectral reflectance. Interestingly, I find that whole genome duplication can have effects on leaf functional traits relevant to both size and ecophysiology, and thus that polyploidy may lead to functional trait differentiation between polyploids and their diploid progenitors.

O gênero Drosera (Droseraceae) compreende cerca de 200 espécies, 30 delas ocorrendo no Brasil. Nesta dissertação, é realizada a revisão taxonômica do clado tetraploide-brasileiro de Drosera, compreendendo 17 espécies e uma variedade. São apresentados e discutidos dados sobre morfologia, ecologia, distribuição geográfica e status de conservação para estas espécies, com mapas de distribuição, ilustrações, fotografias e tabelas comparativas. Os complexos D. graminifolia, D. Montana e D. villosa são discutidos nos capítulos 1, 2 e 3, respectivamente. Além disso, essas três espécies são recircunscritas com base em evidências morfológicas e de sua ecologia. Drosera ascendens, D. spiralis, D. tomentosa e suas duas variedades são restabelecidas, e D. villosa var. latifólia é elevada ao status específico. Drosera chrysolepis é lectotipificada e três novas espécies são descritas. Drosera camporupestris, D. grantsaui, D. graomogolensis, D. quartzicola, D. tentaculata e D. schwackei também pertencem ao clado e são aqui tratadas. Na seção Taxonomia, é apresentada uma chave de identificação e, no anexo II, uma lista com todos os táxons de Drosera ocorrentes no Brasil e aqui aceitos / The genus Drosera (Droseraceae) comprises around 200 species, 30 occurring in Brazil. In this dissertation is carried out the taxonomic revision of the Brazilian-tetraploid clade of Drosera, comprising 17 species and a variety. Here are presented and discussed data on the morphology, ecology, geographic distribution, and conservation status for these species, with distribution maps, drawings, photographs, and comparative tables. The complexes D. graminifolia, D. Montana, and D. villosa are discussed in chapters 1, 2, and 3, respectively. These three species are recircumscribed based on of morphological and ecological evidences. Drosera ascendens, D. spiralis, D. tomentosa and its two varieties are reestablished, and D. villosa var. latifolia is raised to specific rank. Drosera chrysolepis is lectotypified and three new species are described. Drosera camporupestris, D. grantsaui, D. graomogolensis, D. quartzicola, D. tentaculata, and D. schwackei also belong to this clade and are here treated. In section Taxonomy it is presented a dicotomic key and, in appendix II, a list with all Drosera taxa occurring in Brazil here accepted