Life Sciences Commons^™

Rna-Mediated Silencing In Algae: Biological Roles And Tools For Analysis Of Gene Function, Heriberto Cerutti, Xinrong Ma, Joseph Msanne, Timothy Repas

Center for Plant Science Innovation: Faculty and Staff Publications

Algae are a large group of aquatic, typically photosynthetic, eukaryotes that include species from very diverse phylogenetic lineages, from those similar to land plants to those related to protist parasites. The recent sequencing of several algal genomes has provided insights into the great complexity of these organisms. Genomic information has also emphasized our lack of knowledge of the functions of many predicted genes, as well as the gene regulatory mechanisms in algae. Core components of the machinery for RNA-mediated silencing show widespread distribution among algal lineages, but they also seem to have been lost entirely from several species with relatively …

Muts Homolog1 Is A Nucleoid Protein That Alters Mitochondrial And Plastid Properties And Plant Response To High Light, Ying-Zhi Xu, Maria P. Arrieta-Montiel, Kamaldeep S. Virdi, Wilson B. M. De Paula, Joshua R. Widhalm, Gilles J. Basset, Jaime I. Davila, Thomas Elthon, Christian G. Elowsky, Shirley J. Sato, Thomas E. Clemente, Sally Ann Mackenzie

Center for Plant Science Innovation: Faculty and Staff Publications

Mitochondrial-plastid interdependence within the plant cell is presumed to be essential, but measurable demonstration of this intimate interaction is difficult. At the level of cellular metabolism, several biosynthetic pathways involve both mitochondrial- and plastid-localized steps. However, at an environmental response level, it is not clear how the two organelles intersect in programmed cellular responses. Here, we provide evidence, using genetic perturbation of the MutS Homolog1 (MSH1) nuclear gene in five plant species, that MSH1 functions within the mitochondrion and plastid to influence organellar genome behavior and plant growth patterns. The mitochondrial form of the protein participates in DNA recombination …

Delivery Of Prolamins To The Protein Storage Vacuole In Maize Aleurone Cells, Francisca C. Reyes, Taijoon Chung, David Holding, Rudolf Jung, Richard Vierstra, Marisa S. Otegui

Center for Plant Science Innovation: Faculty and Staff Publications

Zeins, the prolamin storage proteins found in maize (Zea mays), accumulate in accretions called protein bodies inside the endoplasmic reticulum (ER) of starchy endosperm cells. We found that genes encoding zeins, a-globulin, and legumin-1 are transcribed not only in the starchy endosperm but also in aleurone cells. Unlike the starchy endosperm, aleurone cells accumulate these storage proteins inside protein storage vacuoles (PSVs) instead of the ER. Aleurone PSVs contain zeinrich protein inclusions, a matrix, and a large system of intravacuolar membranes. After being assembled in the ER, zeins are delivered to the aleurone PSVs in atypical prevacuolar compartments …

Plant Targets For Pseudomonas Syringae Type Iii Effectors: Virulence Targets Or Guarded Decoys?, Anna Block, James R. Alfano

Center for Plant Science Innovation: Faculty and Staff Publications

The phytopathogenic bacterium Pseudomonas syringae can suppress both pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI) by the injection of type III effector (T3E) proteins into host cells. T3Es achieve immune suppression using a variety of strategies including interference with immune receptor signaling, blocking RNA pathways and vesicle trafficking, and altering organelle function. T3Es can be recognized directly or indirectly by resistance proteins monitoring specific T3E targets resulting in ETI. It is presently unclear whether the monitored targets represent bona fide virulence targets or guarded decoys. Extensive overlap between PTI and ETI signaling suggests that T3Es may suppress …

A Plant Dj-1 Homolog Is Essential For Arabidopsis Thaliana Chloroplast Development, Jiusheng Lin, Tara J. Nazarenus, Jeanine L. Frey, Xinwen Liang, Mark A. Wilson, Julie M. Stone

Center for Plant Science Innovation: Faculty and Staff Publications

Protein superfamilies can exhibit considerable diversification of function among their members in various organisms. The DJ-1 superfamily is composed of proteins that are principally involved in stress response and are widely distributed in all kingdoms of life. The model flowering plant Arabidopsis thaliana contains three close homologs of animal DJ-1, all of which are tandem duplications of the DJ-1 domain. Consequently, the plant DJ-1 homologs are likely pseudo-dimeric proteins composed of a single polypeptide chain. We report that one A. thaliana DJ-1 homolog (AtDJ1C) is the first DJ-1 homolog in any organism that is required for viability. Homozygous disruption of …

Two Distinct Roles Of Arabidopsis Homolog Of Trithorax1 (Atx1) At Promoters And Within Transcribed Regions Of Atx1-Regulated Genes, Yong Ding, Zoya Avramova, Michael E. Fromm

Center for Plant Science Innovation: Faculty and Staff Publications

The Arabidopsis thaliana trithorax-like protein, ATX1, shares common structural domains, has similar histone methyltransferase (HMT) activity, and belongs in the same phylogenetic subgroup as its animal counterparts. Most of our knowledge of the role of HMTs in trimethylating lysine 4 of histone H3 (H3K4me3) in transcriptional regulation comes from studies of yeast and mammalian homologs. Little is known about the mechanism by which ATX1, or any other HMT of plant origin, affects transcription. Here, we provide insights into how ATX1 influences transcription at regulated genes, playing two distinct roles. At promoters, ATX1 is required for TATA binding protein (TBP) and …

Mpk6, Sphinganine And The Lcb2a Gene From Serine Palmitoyltransferase Are Required In The Signaling Pathway That Mediates Cell Death Induced By Long Chain Bases In Arabidopsis, Mariana Saucedo-García, Arturo Guevara-Garcia, Ariadna González-Solís, Felipe Cruz-García, Sonia Vázquez-Santana, Jennifer E. Markham, M. Guadalupe Lozano-Rosas, Charles R. Dietrich, Maricela Ramos-Vega, Edgar B. Cahoon, Marina Gavilanes-Ruíz

Center for Plant Science Innovation: Faculty and Staff Publications

• Long chain bases (LCBs) are sphingolipid intermediates acting as second messengers in programmed cell death (PCD) in plants. Most of the molecular and cellular features of this signaling function remain unknown.

• We induced PCD conditions in Arabidopsis thaliana seedlings and analyzed LCB accumulation kinetics, cell ultrastructure and phenotypes in serine palmitoyltransferase (spt), mitogen-activated protein kinase (mpk), mitogenactivated protein phosphatase (mkp1) and lcb-hydroxylase (sbh) mutants.

• The lcb2a-1 mutant was unable to mount an effective PCD in response to fumonisin B1 (FB1), revealing that the LCB2a gene is essential for the …

Structure Function Analysis Of An Adp-Ribosyltransferase Type Iii Effector And Its Rna-Binding Target In Plant Immunity, Byeong-Ryool Jeong, Yan Lin, Anna Joe, Ming Guo, Christin Korneli, Huirong Yang, Ping Wang, Min Yu, Ronald Cerny, Dorothee Staiger, James R. Alfano, Yanhui Xu

Center for Plant Science Innovation: Faculty and Staff Publications

Background: HopU1 ADP-ribosylates GRP7, suppressing plant immunity.

Results: The HopU1 structure has two novel loops required for GRP7 recognition, and HopU1 ribosylates GRP7 at an arginine in position 49 disrupting its function.

Conclusion: HopU1 targets a conserved arginine in GRP7, disabling its ability to bind immunity-related RNA.

Significance: The mechanistic details of how HopU1 recognizes its substrate reveal how HopU1 contributes to pathogenesis.

Structural And Functional Analysis Of The Type Iii Secretion System From Pseudomonas Fluorescens Q8r1-96, Dmitri V. Mavrodi, Anna Joe, Olga V. Mavrodi, Karl A. Hassan, David M. Weller, Ian T. Paulsen, Joyce E. Loper, James R. Alfano, Linda S. Thomashow

Center for Plant Science Innovation: Faculty and Staff Publications

Pseudomonas fluorescens Q8r1-96 represents a group of rhizosphere strains responsible for the suppressiveness of agricultural soils to take-all disease of wheat. It produces the antibiotic 2,4-diacetylphloroglucinol and aggressively colonizes the roots of cereal crops. In this study, we analyzed the genome of Q8r1-96 and identified a type III protein secretion system (T3SS) gene cluster that has overall organization similar to that of the T3SS gene cluster of the plant pathogen Pseudomonas syringae. We also screened a collection of 30 closely related P. fluorescens strains and detected the T3SS genes in all but one of them. The Q8r1-96 genome contained …