Genetic analysis of self-fertilization traits in Nicotiana plumbaginifolia, a derivate of N. longiflora [abstract]

N. plumbaginifolia evolved from N. longiflora and is characterized by a short corolla and the tendency to prior self-fertilize. N. longiflora is a dedicated out-crosser characterized by long, protandrous (male-first) flowers that exhibit little or no self-fertilization. In some native populations where these two species coexist, three morphs can be found (short, intermediate and long). Plants of intermediate characteristics were the subject of study because they showed traits of both N. plumbaginifolia (ability to prior self-pollinate) and of N. longiflora (flowers of mixed length). We are taking two separate approaches in order to observe the genetics behind the morphological differences. First, we selfed three different lines of intermediates (two from N. longiflora and one from N. plumbaginifolia) to determine if the intermediates were F1 hybrids and if morphology was determined by a single gene. If morphology was caused by a single gene, then we expected a 1:2:1 ratio in our selfed progeny. The maternal parent was known for each intermediate plant; however, the paternal source was unknown. If the ratio of the selfed progeny was not 1:2:1 then we know that there are most likely multiple genes determining morphology. After analysis of the morphological distribution in the selfed progeny, I believe that if these plants were hybrids, then they are so after many generations, which would explain the discrepancy in the morphological spectrum. Using family structured data we can identify by linkage analysis the quantitative trait loci involved in the changes to self-fertilization. We can also determine if the intermediates are actual hybrids, or if they evolved separately from one of the two species. The second approach that we took was that we chose ten parents representing all lineages in the population and crossed them to create F1 and F2 generations. We will then use the F2 generation for QTL analysis and create multiple CAPS markers to try to determine genetic differences between the morphs. We are currently working on CAPS markers and searching for genetic polymorphisms. In the future, we would like to be able to classify whether the intermediate morph is an actual hybrid of N. plumbaginifolia and N. longiflora, or if it evolved separately.MU Monsanto Undergraduate Research Fellowshi

Understanding genomic evolution and segregation distortion in solanaceae : a COSII linkage map in Nicotiana

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed on January 26, 2010)Thesis advisor: Dr. Timothy P. Holtsford.M.A. University of Missouri--Columbia 2009.Genetic linkage maps are excellent tools to investigate genomic evolution, genomic structure and quantitative trait loci. In our study, we created comparative linkage maps in a reciprocal cross between Nicotiana longiflora and N. plumbaginifolia. We used genetic markers derived from the Conserved Ortholog Set II (COSII) to investigate synteny between N.longiflora and N. plumbaginifolia (n = 10) and other Solanaceae species (n = 12), such as tomato, pepper and eggplant. We produced two linkage maps; one in a maternal N. longiflora background (43 markers covering 808.1 cM) and a reciprocal map in the maternal N. plumbaginifolia background (54 markers covering 1110.4 cM). Segregation distortion was evident in both backgrounds, especially for the dominant ISSR markers, and was more prevalent in the maternal N. longiflora cross. In both backgrounds, there was a significant preference for the self-fertilizing N. plumbaginifolia allele for distorted markers. Finally, using the COSII markers, we infer many chromosomal rearrangements have occurred since the divergence of Nicotiana and tomato (Solanum lycopersicum) from a common ancestor.Includes bibliographical references

SNP discovery and linkage mapping in Nicotiana

Abstract only availableWe are developing a genetic linkage map in F2 populations descended from a cross between Nicotiana plumbaginafolia and N. longiflora as well as the reciprocal cross. We are using an interspecific cross because is an outbreeder and is a self-pollinator. Combining our linkage map with estimates of self-fertilization in the F2 will allow us to make a Quantitative Trait Locus (QTL) map that may allow us to identify chromosome segments that are associated with self-pollination. We are concentrating on discovering new genetic markers. We are seeking SNPs (Single Nucleotide Polymorphisms) because they are co-dominant markers, i.e., both kinds of homozygotes and the heterozygote can be identified (e.g., AA, Aa, aa). In contrast, dominant markers can only identify the recessive homozygote unambiguously (aa); the dominant homozygote and the heterozygote are indistinguishable (AA = Aa). Therefore, co-dominant genetic markers are much more informative than dominant markers. We are seeking to identify genetic polymorphisms from known COS (Conserved Ortholog Set) loci because COS markers have been used to map many other species. Therefore, our linkage map will allow us to compare the chromosomal locations of these loci in our cross, versus other COS-mapped plants.In order to determine SNPs in the genome of Nicotiana, there are two possible approaches. We can sequence both parents of the F2 population and look for the differences between the two species as well as sequence the heterozygotes and look for differences within the F2. Thus far, we have tried 3 COS loci and found 1 polymorphism. We are using the CAPS procedure to assay the polymorphisms. We use restriction enzymes to cut at specific locations within the primer region and determine if each individual is homozygous dominant, homozygous recessive, or heterozygous.Life Sciences Undergraduate Research Opportunity Progra

Corolla length and autogamy in Nicotiana

Abstract only availableNicotiana has been an interest of study due to its variance in autogamy and floral traits. Species N. plumbaginifolia and N. longiflora are characterized by their difference in flower size and the ability to self pollinate. N. plumbaginifolia is characterized by a short corolla and the tendency to prior self-fertilize, whereas N. longiflora is characterized by long flowers that exhibit little or no self-fertilization. It is important to observe the correlation between floral traits and autogamy in order to understand their influence on self-fertilization. In our study, we measured daily corolla growth and observed when the flower would set fruit or fall off. Our sample included plants of short, medium, and long flowers. The plants of medium length were of particluar interest in our study because they showed traits of both N. plumbaginifolia (ability to prior self-pollinate) and of N. longiflora (flowers of mixed length). The final measurements were run through a statistical analysis of variance using the Plastochron Growth Index (PI). Results showed that flowers of short corolla lengths self fertilized more often and sooner than that of longer lengths. Finally flowers with corollas under 40 millimeters commonly showed traits of prior self-fertilization. From my analysis I determined that corolla length has influence over the flower's ability to self-pollinate.MU Monsanto Undergraduate Research Fellowshi