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Full-Text Articles in Biology

Subset Of Heat-Shock Transcription Factors Required For The Early Response Of Arabidopsis To Excess Light, Hou-Sung Jung, Peter A. Crisp, Gonzalo M. Estavillo, Benjamin Cole Aug 2013

Subset Of Heat-Shock Transcription Factors Required For The Early Response Of Arabidopsis To Excess Light, Hou-Sung Jung, Peter A. Crisp, Gonzalo M. Estavillo, Benjamin Cole

Dartmouth Scholarship

Sunlight provides energy for photosynthesis and is essential for nearly all life on earth. However, too much or too little light or rapidly fluctuating light conditions cause stress to plants. Rapid changes in the amount of light are perceived as a change in the reduced/oxidized (redox) state of photosynthetic electron transport components in chloroplasts. However, how this generates a signal that is relayed to changes in nuclear gene expression is not well understood. We modified redox state in the reference plant, Arabidopsis thaliana, using either excess light or low light plus the herbicide DBMIB (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone), a well-known inhibitor of photosynthetic …


Dirigent Domain-Containing Protein Is Part Of The Machinery Required For Formation Of The Lignin-Based Casparian Strip In The Root, Prashant S. Hosmani, Takehiro Kamiya, John Danku, Sadaf Naseer, Niko Geldner, Mary Lou Guerinot, David Salt Aug 2013

Dirigent Domain-Containing Protein Is Part Of The Machinery Required For Formation Of The Lignin-Based Casparian Strip In The Root, Prashant S. Hosmani, Takehiro Kamiya, John Danku, Sadaf Naseer, Niko Geldner, Mary Lou Guerinot, David Salt

Dartmouth Scholarship

The endodermis acts as a "second skin" in plant roots by providing the cellular control necessary for the selective entry of water and solutes into the vascular system. To enable such control, Casparian strips span the cell wall of adjacent endodermal cells to form a tight junction that blocks extracellular diffusion across the endodermis. This junction is composed of lignin that is polymerized by oxidative coupling of monolignols through the action of a NADPH oxidase and peroxidases. Casparian strip domain proteins (CASPs) correctly position this biosynthetic machinery by forming a protein scaffold in the plasma membrane at the site where …


Scfkmd Controls Cytokinin Signaling By Regulating The Degradation Of Type-B Response Regulators, Hyo Jung Kim, Yi-Hsuan Chiang, Joseph J. Kieber, G. Eric Schaller Jun 2013

Scfkmd Controls Cytokinin Signaling By Regulating The Degradation Of Type-B Response Regulators, Hyo Jung Kim, Yi-Hsuan Chiang, Joseph J. Kieber, G. Eric Schaller

Dartmouth Scholarship

Cytokinins are plant hormones that play critical roles in growth and development. In Arabidopsis, the transcriptional response to cytokinin is regulated by action of type-B Arabidopsis response regulators (ARRs). Although central elements in the cytokinin signal transduction pathway have been identified, mechanisms controlling output remain to be elucidated. Here we demonstrate that a family of F-box proteins, called the kiss me deadly (KMD) family, targets type-B ARR proteins for degradation. KMD proteins form an S-phase kinase-associated PROTEIN1 (SKP1)/Cullin/F-box protein (SCF) E3 ubiquitin ligase complex and directly interact with type-B ARR proteins. Loss-of-function KMD mutants stabilize type-B ARRs and exhibit an …


Arabidopsis Bhlh100 And Bhlh101 Control Iron Homeostasis Via A Fit-Independent Pathway, Alicia B. Sivitz, Victor Hermand, Catherine Curie, Grégory Vert Sep 2012

Arabidopsis Bhlh100 And Bhlh101 Control Iron Homeostasis Via A Fit-Independent Pathway, Alicia B. Sivitz, Victor Hermand, Catherine Curie, Grégory Vert

Dartmouth Scholarship

Iron deficiency induces a complex set of responses in plants, including developmental and physiological changes, to increase iron uptake from soil. In Arabidopsis, many transporters involved in the absorption and distribution of iron have been identified over the past decade. However, little is known about the signaling pathways and networks driving the various responses to low iron. Only the basic helix–loop–helix (bHLH) transcription factor FIT has been shown to control the expression of the root iron uptake machinery genes FRO2 and IRT1. Here, we characterize the biological role of two other iron-regulated transcription factors, bHLH100 and bHLH101, in iron homeostasis. …


Evolution Of Plant Sucrose Uptake Transporters, Anke Reinders, Alicia B. Sivitz, John M. Ward Feb 2012

Evolution Of Plant Sucrose Uptake Transporters, Anke Reinders, Alicia B. Sivitz, John M. Ward

Dartmouth Scholarship

In angiosperms, sucrose uptake transporters (SUTs) have important functions especially in vascular tissue. Here we explore the evolutionary origins of SUTs by analysis of angiosperm SUTs and homologous transporters in a vascular early land plant, Selaginella moellendorffii, and a non-vascular plant, the bryophyte Physcomitrella patens, the charophyte algae Chlorokybus atmosphyticus, several red algae and fission yeast, Schizosaccharomyces pombe. Plant SUTs cluster into three types by phylogenetic analysis. Previous studies using angiosperms had shown that types I and II are localized to the plasma membrane while type III SUTs are associated with vacuolar membrane. SUT homologs were …


Nectar Secondary Compounds Affect Self-Pollen Transfer: Implications For Female And Male Reproduction, Rebecca E. Irwin, Lynn S. Adler Aug 2008

Nectar Secondary Compounds Affect Self-Pollen Transfer: Implications For Female And Male Reproduction, Rebecca E. Irwin, Lynn S. Adler

Dartmouth Scholarship

Pollen movement within and among plants affects inbreeding, plant fitness, and the spatial scale of genetic differentiation. Although a number of studies have assessed how plant and floral traits influence pollen movement via changes in pollinator behavior, few have explored how nectar chemical composition affects pollen transfer. As many as 55% of plants produce secondary compounds in their nectar, which is surprising given that nectar is typically thought to attract pollinators. We tested the hypothesis that nectar with secondary compounds may benefit plants by encouraging pollinators to leave plants after visiting only a few flowers, thus reducing self-pollen transfer. We …