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A Subset Of Arabidopsis Ap2 Transcription Factors Mediates Cytokinin Responses In Concert With A Two-Component Pathway, Aaron M. Rashotte, Michael G. Mason, Claire E. Hutchison, Fernando J. Ferreira, G. Eric Schaller, Joseph J. Kieber Jul 2006

A Subset Of Arabidopsis Ap2 Transcription Factors Mediates Cytokinin Responses In Concert With A Two-Component Pathway, Aaron M. Rashotte, Michael G. Mason, Claire E. Hutchison, Fernando J. Ferreira, G. Eric Schaller, Joseph J. Kieber

Open Dartmouth: Faculty Open Access Articles

The plant hormone cytokinin regulates numerous growth and developmental processes. A signal transduction pathway for cytokinin has been elucidated that is similar to bacterial two-component phosphorelays. In Arabidopsis, this pathway is comprised of receptors that are similar to sensor histidine kinases, histidine-containing phosphotransfer proteins, and response regulators (ARRs). There are two classes of response regulators, the type-A ARRs, which act as negative regulators of cytokinin responses, and the type-B ARRs, which are transcription factors that play a positive role in mediating cytokinin-regulated gene expression. Here we show that several closely related members of the Arabidopsis AP2 gene family of unknown ...


Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong Jan 2006

Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong

Retrospective Theses and Dissertations

Autophagy is a process in which cytoplasmic components are degraded in the vacuole. It occurs when organisms are subjected to environmental stress conditions or during certain stages of development. Upon induction of autophagy, a portion of cytoplasm is surrounded by a double membrane structure to form an autophagosome. The outer membrane of the autophagosome then fuses with the vacuole and the inner membrane and its contents are degraded by vacuolar hydrolases. The morphological characteristics of autophagy have been observed in plants for decades and several autophagy defective mutants have been isolated recently; however, little is known about the molecular mechanism ...


The Mechanism Of Arabidopsis Immutans Variegation , Aigen Fu Jan 2006

The Mechanism Of Arabidopsis Immutans Variegation , Aigen Fu

Retrospective Theses and Dissertations

The Arabidopsis immutans (im) is variegated with green sectors and white sectors containing defective plastids due to a nuclear gene mutation. IM is a plastid terminal oxidase (PTOX) sharing similarity with mitochondrial alternative oxidase (AOX). In order to better understand IM's biological roles and variegation mechanism of im, I characterized im plants at different levels;A structural model of IM, in which the diiron reaction center is composed of two conserved histidine and four glutamate residues, was tested by mutagenesis in vitro and in planta. It that these six conserved residues were found essential for IM activity and do ...


Genomics And Molecular Biology Approaches To Plant-Parasitic Nematode Biology And Parasitism , Axel Armin Elling Jan 2006

Genomics And Molecular Biology Approaches To Plant-Parasitic Nematode Biology And Parasitism , Axel Armin Elling

Retrospective Theses and Dissertations

The plant-parasitic nematodes Pratylenchus penetrans and Heterodera glycines are of major economic importance worldwide. Here, we present a survey of over 1,900 expressed sequence tags (ESTs) for P. penetrans and of almost 22,000 ESTs for H. glycines. Furthermore, we conducted microarray expression profiling for over 6,800 H. glycines genes throughout the life cycle. We identified over 600 H. glycines genes that encode secretory proteins and provide microarray data for all known H. glycines parasitism genes as well as for H. glycines genes with similarity to known plant and microbe sequences. In order to extend these studies, we ...


Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao Jan 2006

Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao

Retrospective Theses and Dissertations

Phytophthora sojae, a hemibiotrophic oomycete, is the causal pathogen of stem and root rot disease of soybean (Glycine max [L.] Merr). The annual soybean yield loss suffered from this disease is valued at about 300 million dollars. A series of single Rps genes protect soybean from the root and stem rot disease. In the last two decades Rps1-k has been the most stable and widely used Phytophthora resistance gene in the major soybean-producing regions of the United States;Two classes of CC-NB-LRR-type Rps1-k genes were isolated from the Rps1-k locus. Representative members from each gene class were expressed in transgenic ...


From Pathway To Regulon In Arabidopsis, Wiesława Izabela Mentzen Jan 2006

From Pathway To Regulon In Arabidopsis, Wiesława Izabela Mentzen

Retrospective Theses and Dissertations

Combined bioinformatic approaches, using genomic and transcriptomic data, are applied to investigate the fatty acid biosynthesis pathway, at the molecular level, and in the context of the system biology of Arabidopsis. Fatty acids are essential components of all known bacterial and eukaryotic cells with critical role in cells as energy reserves and the metabolic precursors for biological membranes. The pathway for fatty acid synthesis seems to be conserved across all living systems. Acetyl-CoA carboxylase, a member of a superfamily of biotin-dependent enzymes, catalyzes the first committed step of the fatty acid biosynthesis pathway. Phylogenetic study exposed complex and intertwined evolutionary ...


The Roles Of Aldehyde Dehydrogenases (Aldhs) In Acetyl-Coa Biosynthesis And Root Elongation In Arabidopsis , Yanling Wei Jan 2006

The Roles Of Aldehyde Dehydrogenases (Aldhs) In Acetyl-Coa Biosynthesis And Root Elongation In Arabidopsis , Yanling Wei

Retrospective Theses and Dissertations

Aldehyde dehydrogenases (ALDHs, EC 1.2.1) oxidize aldehydes into carboxylic acids, and thus are important in regulating the level of toxic aldehydes. ALDHs from eukaryotes were classified into more than 20 families. In mammals Family 2 ALDHs detoxify acetaldehyde and a similar function has been suggested in plants. Specifically, it has been hypothesized that plant Family 2 ALDHs oxidize acetaldehyde generated via ethanolic fermentation and produce acetate for acetyl-CoA biosynthesis through acetyl-CoA synthetase (ACS) in plastids, similar to the yeast pathway termed the "pyruvate dehydrogenase (PDH) bypass". Arabidopsis. thaliana contains three Family 2 ALDHs, two of which are mitochondrial ...