Perceptions of the co-principalship as implemented in High Point, North Carolina

The purposes of this case study were: (1) to present the circumstances surrounding the implementation of the co-principalship and to present the conceptual framework of the co-principalship; (2) to present the goals the coprincipalship was expected to achieve; (3} to present the _perceptions of the following groups as to the achievement of the goals of the co-principalship as implemented in High Point: school board members, superintendents, central office administrators, co-principals, and teachers; (4} to present the perceptions of the groups noted above along with those of students and parents as to the roles, duties, and responsibilities of the co-principals in High Point; (5) to present the similarities/differences in perceptions of the groups noted in Point 4; and (6) to present the strengths and/or weaknesses of the co-principalship as perceived by the groups noted in Point 3. Surveys and interviews were used to collect data from 1,004 respondents, who were members of one of the seven subgroups involved in the study. Additionally, High Point Public School documents were used in completing this study

The Populus holobiont: dissecting the effects of plant niches and genotype on the microbiome

Background: Microorganisms serve important functions within numerous eukaryotic host organisms. An understanding of the variation in the plant niche-level microbiome, from rhizosphere soils to plant canopies, is imperative to gain a better understanding of how both the structural and functional processes of microbiomes impact the health of the overall plant holobiome. Using Populus trees as a model ecosystem, we characterized the archaeal/bacterial and fungal microbiome across 30 different tissue-level niches within replicated Populus deltoides and hybrid Populus trichocarpa × deltoides individuals using 16S and ITS2 rRNA gene analyses. Results: Our analyses indicate that archaeal/bacterial and fungal microbiomes varied primarily across broader plant habitat classes (leaves, stems, roots, soils) regardless of plant genotype, except for fungal communities within leaf niches, which were greatly impacted by the host genotype. Differences between tree genotypes are evident in the elevated presence of two potential fungal pathogens, Marssonina brunnea and Septoria sp., on hybrid P. trichocarpa × deltoides trees which may in turn be contributing to divergence in overall microbiome composition. Archaeal/bacterial diversity increased from leaves, to stem, to root, and to soil habitats, whereas fungal diversity was the greatest in stems and soils. Conclusions: This study provides a holistic understanding of microbiome structure within a bioenergy relevant plant host, one of the most complete niche-level analyses of any plant. As such, it constitutes a detailed atlas or map for further hypothesis testing on the significance of individual microbial taxa within specific niches and habitats of Populus and a baseline for comparisons to other plant species

Increased Resistance of Bt Aspens to Phratora vitellinae (Coleoptera) Leads to Increased Plant Growth under Experimental Conditions

One main aim with genetic modification (GM) of trees is to produce plants that are resistant to various types of pests. The effectiveness of GM-introduced toxins against specific pest species on trees has been shown in the laboratory. However, few attempts have been made to determine if the production of these toxins and reduced herbivory will translate into increased tree productivity. We established an experiment with two lines of potted aspens (Populus tremula×Populus tremuloides) which express Bt (Bacillus thuringiensis) toxins and the isogenic wildtype (Wt) in the lab. The goal was to explore how experimentally controlled levels of a targeted leaf beetle Phratora vitellinae (Coleoptera; Chrysomelidae) influenced leaf damage severity, leaf beetle performance and the growth of aspen. Four patterns emerged. Firstly, we found clear evidence that Bt toxins reduce leaf damage. The damage on the Bt lines was significantly lower than for the Wt line in high and low herbivory treatment, respectively. Secondly, Bt toxins had a significant negative effect on leaf beetle survival. Thirdly, the significant decrease in height of the Wt line with increasing herbivory and the relative increase in height of one of the Bt lines compared with the Wt line in the presence of herbivores suggest that this also might translate into increased biomass production of Bt trees. This realized benefit was context-dependent and is likely to be manifested only if herbivore pressure is sufficiently high. However, these herbivore induced patterns did not translate into significant affect on biomass, instead one Bt line overall produced less biomass than the Wt. Fourthly, compiled results suggest that the growth reduction in one Bt line as indicated here is likely due to events in the transformation process and that a hypothesized cost of producing Bt toxins is of subordinate significance

Boundary genes in regulation and evolution of secondary growth

Many extant land plants display secondary growth originating in a lateral meristem known as vascular cambium. A conspicuous product of secondary growth is wood which dominates terrestrial ecosystem biomass. Despite the economic and ecological significance of the process the underlying molecular mechanism are still poorly understood. We have recently shown that members of the LBD transcription factor family play function in control of secondary growth. Here we propose a mechanistic model of LBD regulatory roles. We also show how these roles may be linked to evolutionary changes in level and pattern of wood formation that provide structural and functional innovations in wood anatomy in relation to species growth habit and biology