Won't you be my neighbor? An analysis of the effect of density on floral and nectar traits in Nicotiana alata

Abstract only availableIt has been shown that heritable, genetic variability can change in response to different environmental conditions (Hoffmann and Merila 1999) and also that some plants can sense proximate neighbors and change their growth patterns accordingly (Pierik et. al., 2003). In order to study the effects of environmental variation on the floral and nectar traits we have imposed three different density treatments (high, medium and low) in a field plot of Nicotiana alata. To analyze the density effect I have investigated the genetic (VE), environmental, additive (VA) and phenotypic (VP) variances for each of the three density treatments. These variances will allow me to calculate values for the heritability (VA/VP) of nectar and floral traits in N. alata. By performing a quantitative genetic analysis using a partial diallel breeding design, these quantitative variances were calculated. Genetic variance was also estimated using ISSR markers and determining the percent of bands that are shared among sibs and half sibs. Results will be shown on poster. Sources Cited: Hoffmann Ary A., and Merila, Juha. “Heritable variation and evolution under favourable and unfavourable conditions”. TREE (1999) 14 (3): 96-103. Pierik, R., Visser, E.J.W., Droon, H. DE. And Voesenek, C.J. “Ethylene is required in tobacco to successfully compete with proximate neighbours. Plant, Cell and Environment (2003) 26: 1229-1234.Plant Genomics Internships @ M

Differences in pollen to ovule ratios and reproductive organ size between autogamous and crossing species of Nicotiana

Abstract only availableNicotiana is commonly studied due to the presence of both highly autogamous species, such as plumbaginifolia, and crossing species, such as alata. There are also species that expend energy to a mix of selfing and crossing, such as longiflora. It has been speculated that there are morphological differences between these types. Specifically, my study concentrates on the differences in pollen to ovule ratios and the size of the sexual parts. I hypothesize a lower pollen to ovule ratio in selfers as the plant will not need excessive pollen for dispersal. Sexual parts of the plant should be larger in cross breeding plants to hold the larger quantity of pollen or ovules. It is important to understand the differences between autogamous plants and cross breeding plants so as to better understand the costs and benefits associated with autogamy. Measurements that I took include anther length and width, ovary length and width, and position of the flower on the inflorescence. I have developed protocols to evenly spread the pollen of one locule in a solution on a slide and to show and preserve one carpel of the ovary. These protocols were designed so that I was able to take pictures through a compound and dissecting scope, save the pictures as JPEG files and count the pollen and ovules with the help of a computer program. Currently there is not enough data to run any statistical tests. I will run all measurements and counts through an analysis of variance test to determine statistical differences. Judging on the data I have thus far, I predict a significant difference between pollen to ovule ratios. There may be little difference between anther and ovule size.MU Monsanto Undergraduate Research Fellowshi

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

Development of CAPS markers for Nicotiana

Abstract only availableThe area in which the ranges of Nicotiana longiflora and Nicotiana plumbaginifolia overlap presents an ideal system for studying the interaction and hybridization of a selfing and an outcrossing species. N. longiflora is characterized by long corollas and self compatibility but sets little fruit on its own due to anther stigma separation. N. plumbaginifolia exhibits shorter corollas and self pollinates almost all of it's flowers. A third morph with medium length corollas is found in populations comprised of both species. It seems likely that this morph is a hybrid. In order to better understand how hybridization occurred and the genetic consequences of species interaction, we plan to perform pollen races in which we will allow self, out crossed, and inter-specific pollen to compete on the same style. Pollen competes and is selected through a variety of mechanisms including stigma and/or style clogging, pollen tube germination success and speed of growth, and differential seed abortion. The winners of the races will be determined through paternity tests of the resulting off spring. Using this method allows us to examine the genetic consequences of all the stages of pollen competition. We will test for paternity using molecular markers in the form of single nucleotide polymorphisms in restriction enzyme recognition sites (CAPS markers). We used DNA sequences of randomly chosen genetic loci to develop CAPS markers. We found a high degree of variability within our population, however only loci at which an individual is heterozygous are useful, so most of the polymorphisms we found cannot serve as markers. At this point the most promising marker seems to be SNPs in the recognition site for Taq I on the gene for Cu-Zn superoxide dismutase.NSF-REU Program in Biological Sciences & Biochemistr

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