Life Sciences Commons^™

Arp2/3-Independent Wave/Scar Pathway And Class Xi Myosin Control Sperm Nuclear Migration In Flowering Plants, Mohammad F. Ali, Umma Fatema, Xiongbo Peng, Samuel W. Hacker, Daisuke Maruyama, Meng-Xiang Sun, Tomokazu Kawashima

Plant and Soil Sciences Faculty Publications

After eukaryotic fertilization, gamete nuclei migrate to fuse parental genomes in order to initiate development of the next generation. In most animals, microtubules control female and male pronuclear migration in the zygote. Flowering plants, on the other hand, have evolved actin filament (F-actin)-based sperm nuclear migration systems for karyogamy. Flowering plants have also evolved a unique double-fertilization process: two female gametophytic cells, the egg and central cells, are each fertilized by a sperm cell. The molecular and cellular mechanisms of how flowering plants utilize and control F-actin for double-fertilization events are largely unknown. Using confocal microscopy live-cell imaging with a …

Mechanistic Insights Into Glucan Phosphatase Activity Against Polyglucan Substrates, David A. Meekins, Madushi Raththagala, Kyle D. Auger, Benjamin D. Turner, Diana Santelia, Oliver Kötting, Matthew S. Gentry, Craig W. Vander Kooi

Molecular and Cellular Biochemistry Faculty Publications

Glucan phosphatases are central to the regulation of starch and glycogen metabolism. Plants contain two known glucan phosphatases, Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), which dephosphorylate starch. Starch is water-insoluble and reversible phosphorylation solubilizes its outer surface allowing processive degradation. Vertebrates contain a single known glucan phosphatase, laforin, that dephosphorylates glycogen. In the absence of laforin, water-soluble glycogen becomes insoluble, leading to the neurodegenerative disorder Lafora Disease. Because of their essential role in starch and glycogen metabolism glucan phosphatases are of significant interest, yet a comparative analysis of their activities against diverse glucan substrates has not been established. …

Cpsf30 At The Interface Of Alternative Polyadenylation And Cellular Signaling In Plants, Manohar Chakrabarti, Arthur G. Hunt

Plant and Soil Sciences Faculty Publications

Post-transcriptional processing, involving cleavage of precursor messenger RNA (pre mRNA), and further incorporation of poly(A) tail to the 3' end is a key step in the expression of genetic information. Alternative polyadenylation (APA) serves as an important check point for the regulation of gene expression. Recent studies have shown widespread prevalence of APA in diverse systems. A considerable amount of research has been done in characterizing different subunits of so-called Cleavage and Polyadenylation Specificity Factor (CPSF). In plants, CPSF30, an ortholog of the 30 kD subunit of mammalian CPSF is a key polyadenylation factor. CPSF30 in the model plant Arabidopsis …

Integration Of Developmental And Environmental Signals Via A Polyadenylation Factor In Arabidopsis, Man Liu, Ruqiang Xu, Carrie Merrill, Liwei Hong, Carol Von Lanken, Arthur G. Hunt, Qingshun Q. Li

Plant and Soil Sciences Faculty Publications

The ability to integrate environmental and developmental signals with physiological responses is critical for plant survival. How this integration is done, particularly through posttranscriptional control of gene expression, is poorly understood. Previously, it was found that the 30 kD subunit of Arabidopsis cleavage and polyadenylation specificity factor (AtCPSF30) is a calmodulin-regulated RNA-binding protein. Here we demonstrated that mutant plants (oxt6) deficient in AtCPSF30 possess a novel range of phenotypes--reduced fertility, reduced lateral root formation, and altered sensitivities to oxidative stress and a number of plant hormones (auxin, cytokinin, gibberellic acid, and ACC). While the wild-type AtCPSF30 (C30G) was …

Mono- And Digalactosyldiacylglycerol Lipids Function Nonredundantly To Regulate Systemic Acquired Resistance In Plants, Qing-Ming Gao, Keshun Yu, Ye Xia, M. B. Shine, Caixia Wang, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

Plant Pathology Faculty Publications

The plant galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) have been linked to the anti-inflammatory and cancer benefits of a green leafy vegetable diet in humans due to their ability to regulate the levels of free radicals like nitric oxide (NO). Here, we show that DGDG contributes to plant NO as well as salicylic acid biosynthesis and is required for the induction of systemic acquired resistance (SAR). In contrast, MGDG regulates the biosynthesis of the SAR signals azelaic acid (AzA) and glycerol-3-phosphate (G3P) that function downstream of NO. Interestingly, DGDG is also required for AzA-induced SAR, but MGDG is not. Notably, …

Variation In Arabidopsis Flowering Time Associated With Cis-Regulatory Variation In Constans, Ulises Rosas, Yu Mei, Qiguang Xie, Joshua A. Banta, Royce W. Zhou, Gabriela Seufferheld, Silvia Gerard, Lucy Chou, Naeha Bhambhra, Jennifer Deane Parks, Jonathon M. Flowers, C. Robertson Mcclung, Yoshie Hanzawa, Michael D. Purugganan

Biology Faculty Publications and Presentations

The onset of flowering, the change from vegetative to reproductive development, is a major life history transition in flowering plants. Recent work suggests that mutations in cis-regulatory mutations should play critical roles in the evolution of this (as well as other) important adaptive traits, but thus far there has been little evidence that directly links regulatory mutations to evolutionary change at the species level. While several genes have previously been shown to affect natural variation in flowering time in Arabidopsis thaliana, most either show protein-coding changes and/or are found at low frequency (o5%). Here we identify and characterize natural variation …

Induced Transcriptional Profiling Of Phenylpropanoid Pathway Genes Increased Flavonoid And Lignin Content In Arabidopsis Leaves In Response To Microbial Products, Mohammad Babar Ali, David H. Mcnear

Plant and Soil Sciences Faculty Publications

BACKGROUND: The production and use of biologically derived soil additives is one of the fastest growing sectors of the fertilizer industry. These products have been shown to improve crop yields while at the same time reducing fertilizer inputs to and nutrient loss from cropland. The mechanisms driving the changes in primary productivity and soil processes are poorly understood and little is known about changes in secondary productivity associated with the use of microbial products. Here we investigate secondary metabolic responses to a biologically derived soil additive by monitoring changes in the phenlypropanoid (PP) pathway in Arabidopsis thaliana.

RESULTS: This study …

An Intergenic Region Shared By At4g35985 And At4g35987 In Arabidopsis Thaliana Is A Tissue Specific And Stress Inducible Bidirectional Promoter Analyzed In Transgenic Arabidopsis And Tobacco Plants, Joydeep Banerjee, Dipak K. Sahoo, Nrisingha Dey, Robert Houtz, Indu B. Maiti

Kentucky Tobacco Research and Development Center Faculty Publications

On chromosome 4 in the Arabidopsis genome, two neighboring genes (calmodulin methyl transferase At4g35987 and senescence associated gene At4g35985) are located in a head-to-head divergent orientation sharing a putative bidirectional promoter. This 1258 bp intergenic region contains a number of environmental stress responsive and tissue specific cis-regulatory elements. Transcript analysis of At4g35985 and At4g35987 genes by quantitative real time PCR showed tissue specific and stress inducible expression profiles. We tested the bidirectional promoter-function of the intergenic region shared by the divergent genes At4g35985 and At4g35987 using two reporter genes (GFP and GUS) in both orientations in transient tobacco protoplast and …

Overexpression Of Constans Homologs Co1 And Co2 Fails To Alter Normal Reproductive Onset And Fall Bud Set In Woody Perennial Poplar., Chuan-Yu Hsu, Joshua P. Adams, Kyoungok No, Haiying Liang, Richard Meilan, Olga Pechanova, Abdelali Barakat, John E. Carlson, Grier P. Page, Cetin Yuceer

College of Forest Resources Publications and Scholarship

CONSTANS (CO) is an important flowering-time gene in the photoperiodic flowering pathway of annual Arabidopsis thaliana in which overexpression of CO induces early flowering, whereas mutations in CO cause delayed flowering. The closest homologs of CO in woody perennial poplar (Populus spp.) are CO1 and CO2. A previous report showed that the CO2/FLOWERING LOCUS T1 (FT1) regulon controls the onset of reproduction in poplar, similar to what is seen with the CO/FLOWERING LOCUS T (FT) regulon in Arabidopsis. The CO2/FT1 regulon was also reported to control fall bud set. Our long-term field observations show that overexpression of CO1 and CO2 …

Sag101 Forms A Ternary Complex With Eds1 And Pad4 And Is Required For Resistance Signaling Against Turnip Crinkle Virus, Shifeng Zhu, Rae-Dong Jeong, Srivathsa C. Venugopal, Ludmila Lapchyk, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

Plant Pathology Faculty Publications

EDS1, PAD4, and SAG101 are common regulators of plant immunity against many pathogens. EDS1 interacts with both PAD4 and SAG101 but direct interaction between PAD4 and SAG101 has not been detected, leading to the suggestion that the EDS1-PAD4 and EDS1-SAG101 complexes are distinct. We show that EDS1, PAD4, and SAG101 are present in a single complex in planta. While this complex is preferentially nuclear localized, it can be redirected to the cytoplasm in the presence of an extranuclear form of EDS1. PAD4 and SAG101 can in turn, regulate the subcellular localization of EDS1. We also show that the Arabidopsis genome …

Argonaute10 And Argonaute1 Regulate The Termination Of Floral Stem Cells Through Two Micrornas In Arabidopsis, Lijuan Ji, Xigang Liu, Jun Yan, Wenming Wang, Rae Eden Yumul, Yun Ju Kim, Thanh Theresa Dinh, Jun Liu, Xia Cui, Binglian Zheng, Manu Agarwal, Chunyan Liu, Xiaofeng Cao, Guiliang Tang, Xuemei Chen

Plant and Soil Sciences Faculty Publications

Stem cells are crucial in morphogenesis in plants and animals. Much is known about the mechanisms that maintain stem cell fates or trigger their terminal differentiation. However, little is known about how developmental time impacts stem cell fates. Using Arabidopsis floral stem cells as a model, we show that stem cells can undergo precise temporal regulation governed by mechanisms that are distinct from, but integrated with, those that specify cell fates. We show that two microRNAs, miR172 and miR165/166, through targeting APETALA2 and type III homeodomain-leucine zipper (HD-Zip) genes, respectively, regulate the temporal program of floral stem cells. In particular, …

Substrates Of The Arabidopsis Thaliana Protein Isoaspartyl Methyltransferase 1 Identified Using Phage Display And Biopanning, Tingsu Chen, Nihar Nayak, Susmita Maitra Majee, Jonathan Lowenson, Kim R. Schäfermeyer, Alyssa C. Eliopoulos, Taylor D. Lloyd, Randy Dinkins, Sharyn E. Perry, Nancy R. Forsthoefel, Steven G. Clarke, Daniel M. Vernon, Zhaohui Sunny Zhou, Tomas Rejtar, A. Bruce Downie

Horticulture Faculty Publications

The role of protein isoaspartyl methyltransferase (PIMT) in repairing a wide assortment of damaged proteins in a host of organisms has been inferred from the affinity of the enzyme for isoaspartyl residues in a plethora of amino acid contexts. The identification of PIMT target proteins in plant seeds, where the enzyme is highly active and proteome long-lived, has been hindered by large amounts of isoaspartate-containing storage proteins. Mature seed phage display libraries circumvented this problem. Inclusion of the PIMT co-substrate, S-adenosylmethionine (AdoMet), during panning permitted PIMT to retain aged phage in greater numbers than controls lacking co-substrate or when …

Enhanced Disease Susceptibility 1 And Salicylic Acid Act Redundantly To Regulate Resistance Gene-Mediated Signaling, Srivathsa C. Venugopal, Rae-Dong Jeong, Mihir Kumar Mandal, Shifeng Zhu, A. C. Chandra-Shekara, Ye Xia, Matthew Hersh, Arnold J. Stromberg, Duroy Navarre, Aardra Kachroo, Pradeep Kachroo

Plant Pathology Faculty Publications

Resistance (R) protein-associated pathways are well known to participate in defense against a variety of microbial pathogens. Salicylic acid (SA) and its associated proteinaceous signaling components, including enhanced disease susceptibility 1 (EDS1), non-race-specific disease resistance 1 (NDR1), phytoalexin deficient 4 (PAD4), senescence associated gene 101 (SAG101), and EDS5, have been identified as components of resistance derived from many R proteins. Here, we show that EDS1 and SA fulfill redundant functions in defense signaling mediated by R proteins, which were thought to function independent of EDS1 and/or SA. Simultaneous mutations in EDS1 and the SA-synthesizing enzyme SID2 compromised hypersensitive response and/or …

Distinctive Interactions Of The Arabidopsis Homolog Of The 30 Kd Subunit Of The Cleavage And Polyadenylation Specificity Factor (Atcpsf30) With Other Polyadenylation Factor Subunits, Suryadevara Rao, Randy D. Dinkins, Arthur G. Hunt

Plant and Soil Sciences Faculty Publications

BACKGROUND: The Arabidopsis ortholog of the 30 kD subunit of the mammalian Cleavage and Polyadenylation Specificity Factor (AtCPSF30) is an RNA-binding endonuclease that is associated with other Arabidopsis CPSF subunits (orthologs of the 160, 100, and 73 kD subunits of CPSF). In order to further explore the functions of AtCPSF30, the subcellular distribution of the protein was examined by over-expressing fusion proteins containing fluorescent reporters linked to different CPSF subunits.

RESULTS: It was found that AtCPSF30 by itself localizes, not to the nucleus, but to the cytoplasm. AtCPSF30 could be found in the nucleus when co-expressed with AtCPSF160 or AtCPSF73(I), …

A Polyadenylation Factor Subunit Implicated In Regulating Oxidative Signaling In Arabidopsis Thaliana, Jingxian Zhang, Bala Subrahmanyam Addepalli, Kil-Young Yun, Arthur G. Hunt, Ruqiang Xu, Suryadevara Rao, Qingshun Q. Li, Deane L. Falcone

Kentucky Tobacco Research and Development Center Faculty Publications

BACKGROUND: Plants respond to many unfavorable environmental conditions via signaling mediated by altered levels of various reactive oxygen species (ROS). To gain additional insight into oxidative signaling responses, Arabidopsis mutants that exhibited tolerance to oxidative stress were isolated. We describe herein the isolation and characterization of one such mutant, oxt6.

METHODOLOGY/PRINCIPAL FINDINGS: The oxt6 mutation is due to the disruption of a complex gene (At1g30460) that encodes the Arabidopsis ortholog of the 30-kD subunit of the cleavage and polyadenylation specificity factor (CPSF30) as well as a larger, related 65-kD protein. Expression of mRNAs encoding Arabidopsis CPSF30 alone was able to …

Arabidopsis Mrna Polyadenylation Machinery: Comprehensive Analysis Of Protein-Protein Interactions And Gene Expression Profiling, Arthur G. Hunt, Ruqiang Xu, Balasubrahmanyam Addepalli, Suryadevara Rao, Kevin P. Forbes, Lisa R. Meeks, Denghui Xing, Min Mo, Hongwei Zhao, Amrita Bandyopadhyay, Lavanya Dampanaboina, Amanda Marion, Carol Von Lanken, Qingshun Quinn Li

Plant and Soil Sciences Faculty Publications

BACKGROUND: The polyadenylation of mRNA is one of the critical processing steps during expression of almost all eukaryotic genes. It is tightly integrated with transcription, particularly its termination, as well as other RNA processing events, i.e. capping and splicing. The poly(A) tail protects the mRNA from unregulated degradation, and it is required for nuclear export and translation initiation. In recent years, it has been demonstrated that the polyadenylation process is also involved in the regulation of gene expression. The polyadenylation process requires two components, the cis-elements on the mRNA and a group of protein factors that recognize the cis-elements and …

Patellin1, A Novel Sec14-Like Protein, Localizes To The Cell Plate And Binds Phosphoinositides, T. Peterman, Yamini Ohol, Lisa Mcreynolds, Elizabeth Luna

Elizabeth J. Luna

Membrane trafficking is central to construction of the cell plate during plant cytokinesis. Consequently, a detailed understanding of the process depends on the characterization of molecules that function in the formation, transport, targeting, and fusion of membrane vesicles to the developing plate, as well as those that participate in its consolidation and maturation into a fully functional partition. Here we report the initial biochemical and functional characterization of patellin1 (PATL1), a novel cell-plate-associated protein that is related in sequence to proteins involved in membrane trafficking in other eukaryotes. Analysis of the Arabidopsis genome indicated that PATL1 is one of a …

A Novel Endonuclease Activity Associated With The Arabidopsis Ortholog Of The 30-Kda Subunit Of Cleavage And Polyadenylation Specificity Factor, Balasubrahmanyam Addepalli, Arthur G. Hunt

Plant and Soil Sciences Faculty Publications

The polyadenylation of messenger RNAs is mediated by a multi-subunit complex that is conserved in eukaryotes. Among the most interesting of these proteins is the 30-kDa-subunit of the Cleavage and Polyadenylation Specificity Factor, or CPSF30. In this study, the Arabidopsis CPSF30 ortholog, AtCPSF30, is characterized. This protein possesses an unexpected endonucleolytic activity that is apparent as an ability to nick and degrade linear as well as circular single-stranded RNA. Endonucleolytic action by AtCPSF30 leaves RNA 3′ ends with hydroxyl groups, as they can be labeled by RNA ligase with [³²P]-cytidine-3′,5′-bisphosphate. Mutations in the first of the three CCCH …