No description available.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.48-50).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1958) no. 6, p. 1156-1157. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 75-78).

The onset of reproduction is an important trait and is controlled by the FT1 locus in poplar (Populus sp.). Sequence variation in this locus is not well-understood. This study's aim is to identify sequence variation in the FT1 locus in a small population of Populus deltoides with varying reproductive onset. Gene specific primers were designed to amplify FT from 14 genotypes. The sequence analysis showed 12 single nucleotide polymorphisms and four insertion-deletion sites located in introns of FT1. No connection was observed between the identified polymorphisms and variation in reproductive onset. Further DNA sequencing of the genotypes needs to be done on the promoter region of FT1 to conduct an association study to statistically assess the connection between polymorphisms and phenotypic variation in a larger population. This information is expected to help us understand the genetic basis of phenotypic variation in reproductive onset.

No description available.

Cotton is a very important economical crop in the U.S. and throughout the world. The developments in molecular biology offer new and innovative approaches toward evaluating and understanding genetic mechanisms of important agronomical traits. Bacterial artificial chromosome (BAC) libraries have rapidly become the preferred choice for physical mapping. BAC-derived microsatellite or simple sequence repeats (SSRs) markers facilitate the integration of physical and genetic recombination maps. The first objective in this research was to identify chromosome locations of a set of BAC-derived SSR markers in tetraploid cotton. A total of 192 SSR primer pairs were derived from BAC clones of an Upland cotton (Gossypium hirsutum L.) genetic standard line TM-1. Using deletion analysis method, we assigned 39 markers out of the 192 primer pairs to 18 different chromosomes or chromosome arms. Chromosomal assignment of these markers will help to improve the current cotton genetic linkage maps and facilitate positional candidate gene cloning, comparative genome analysis, and the coordination of chromosome-based genome sequencing projects. Wild race stocks (Gossypium spp.) represent valuable resources for genetic improvement. Most primitive accessions are photoperiod sensitive; they do not flower under the long days of the U.S. cotton belt. Molecular markers were used to locate quantitative trait loci (QTLs) for node of first fruiting branch (NFB), node of first open boll (NOB), and fruiting score (FS). An F2 population consisted of 251 plants from the cross of a day neutral cultivar Deltapine 61, and a photoperiod sensitive accession Texas 701, were used in this study. For each trait, three major QTLs were mapped to chromosome 16, 21, and 25. QTL analysis was also conducted in two F2 populations generated from the cross between Deltapine 61 and two photoperiod sensitive accessions (T1107, PI 607174; T1354, PI 530082) of Upland cotton (G. hirsutum L.). QTL analysis indicated that NFB differed between the two F2 populations. Two major QTLs (q-NFB-c21-1 and q-NFB-c25-1) were found in population 1107; whereas, only one (q-NFB-c25-1) was important in population 1354. Discovering QTLs associated with flowering time may have the potential to facilitate day neutral conversion of wild photoperiod sensitive accessions.

Flowering is one of the most important stages in determining the successful survival and spread in plants. The duration of the flowering period is closely associated with successful reproduction, making it essential to understand the importance and effects of the length of flowering on various macroecological variables across plant species. The effects of the length of flowering periods on the distribution range size of species have seldom been investigated. This project aims to identify any macroecological relationship that may exist between the length of flowering periods and the distribution ranges of plant species endemic to the eastern part of South Africa, a region well known for its floral diversity. Range size and flowering phenology data were collected for several genera that are centred in the region (Cussonia, Gymnosporia, Searsia, Streptocarpus, Pavetta, Plectranthus, Crinum, Eulophia, Gladiolus, Kniphofia, Satyrium, Watsonia and Zantedeschia). At genus level, the relationship varied considerably. While significant correlations between the two variables were retrieved in four genera, the meaning of these patterns differed. In some cases, these suggested that a larger range was achieved through successful pollination due to extended flowering periods, whereas in others, it is probably just an effect of different flowering seasons in different areas where the range is large enough to comprise diverse climates. When incorporating variables such as growth form (narrowly and broadly-defined) and genus identity in analyses of covariance between flowering durations and various measures of distribution, the association of genera was far greater than that of growth form. It can be concluded that both range size and the length of the flowering season are the result of numerous factors acting jointly, which differ across plant groups and are likely to be susceptible to changes in climate and biological invasions. This means that the relationship between range size and flowering period is driven by different factors in different genera, suggesting that the conservation of plant diversity in the face of global change will have to consider the complexity of flowering patterns, and it is likely that lineage-specific approaches for different plant groups will be necessary. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2012.

Premise of research. The duration and intensity of flowering overlap among plants are the first determiners of the potential for pollinator-mediated plant-plant interactions. Yet, our ability to describe community-wide patterns of coflowering, and thus understand its impact on the structure of plant-pollinator communities, is limited. Methodology. We present a conceptual framework for how network theory can reveal structural properties that are ecologically relevant in diverse coflowering communities. Coflowering modules, in particular, may suggest that groups of species coflower more strongly (clustering) with each other than with other species (over-dispersion) in the community. Such a finding would indicate that competitive and facilitative interactions do not act alone but instead act simultaneously to mediate the assembly of coflowering communities. We illustrate our conceptual framework in four diverse coflowering communities in the serpentine seeps in northern California. Pivotal results. Our coflowering networks vary in size and degree but not in overall connectance, suggesting that both intrinsic community features (species richness) and ecological constraints (length of flowering season) play a role in mediating coflowering community structure (distribution of frequency and intensity of flowering overlap among plant species). We show, for the first time, that groups of species tend to coflower more strongly with each other than with other species in a community, supporting the idea that competition and facilitation are not mutually exclusive processes mediating coflowering community assembly. Our results show that the degree of modularity is not sensitive to the number of coflowering species within each community, suggesting that ecological factors may be more important in driving this pattern. Conclusions. Coflowering networks have the potential to advance our understanding of the causes and consequences of flowering overlap in diverse plant communities by revealing a more in-depth and novel characterization of coflowering community structure. Such characterization will allow for a better understanding of the importance of coflowering patterns in mediating the structure of plant-pollinator interactions.

Field pea (Pisum sativum L.) as a cool season legume crop is sensitive to high day time temperature, especially during flowering. A population of 107 recombinant inbred lines (RILs) known as PR-11 was made from the cross of CDC Centennial (heat tolerant cultivar) X CDC Sage (heat sensitive cultivar) with the objectives of screening heat tolerant traits during flowering and subsequent seed development, and to map the quantitative trait loci (QTLs) responsible for these traits. Experiments were carried out in 2012-2014. PR-11 was seeded at normal seeding dates in 2012 and 2013 at Saskatoon (52º12’N, 106º63’W) and Rosthern (52º66’N, 106º33’W) in Canada, and in 2014 PR-11 was seeded at both normal and late seeding (three weeks later than normal) dates at one location, Saskatoon. Correlation analyses demonstrated that the duration of flowering (DOF) was positively associated with final seed yield under both normal and late seeding date conditions. Yield component traits on the main-stem [reproductive node number (Rnode), pod number (Pod), seed number per pod (Seed), single seed weight (SSW)] were significantly associated with main-stem seed yield, among which pod number appeared to be the component most positively associated with seed yield. However, yield on the main-stem was not significantly associated with seed yield at the plot level, which inferred that the contribution of seed yield on side branches was important. A genetic map consisting of 369 SNPs markers with a total coverage of 746 cM was developed using JoinMap 4.0. A total of 14 QTLs were detected under environments with normal seeding date, six for flowering traits, and eight for yield component traits. Eight QTLs were identified at late seeding, four for flowering traits and four for yield component traits. The total variation in days to flowering (DTF), DOF, Pod, Seed, SSW and grain yield that were each explained by the QTLs under normal seeding environments was 24 %, 43%, 15%, 32%, 34% and 21%, respectively. The QTLs together accounted for 43% of DTF variation, 14% of DOF variation, 17% of Pod variation, 12% of SSW variation and 12% of grain yield variation at the late seeding date. Lines PR-11-2, PR-11-88 and PR-11-91 performed as the top yielding lines under both normal and late seeding environments, and could be considered as heat tolerant lines.