Arabidopsis ABA-Activated Kinase MAPKKK18 is Regulated by Protein Phosphatase 2C ABI1 and the Ubiquitin-Proteasome Pathway
In this study, an effort was made to elucidate the role of MAP kinase kinase kinase18 (MKKK18) in relation to ABA signaling and response. The MKKK18 knockout lines showed more vigorous root growth, decreased abaxial stomatal index and increased stomatal aperture under normal growth conditions, compared with the control wild-type Columbia line. In addition to transcriptional regulation of the MKKK18 promoter by ABA, we demonstrated using in vitro and in vivo kinase assays that the kinase activity of MKKK18 was regulated by ABA. Analysis of the cellular localization of MKKK18 showed that the active kinase was targeted specif...
Source: Plant and Cell Physiology - December 10, 2015 Category: Cytology Authors: Mitula, F., Tajdel, M., Ciesla, A., Kasprowicz-Maluski, A., Kulik, A., Babula-Skowronska, D., Michalak, M., Dobrowolska, G., Sadowski, J., Ludwikow, A. Tags: Regular Papers Source Type: research
A Functional EXXEK Motif is Essential for Proton Coupling and Active Glucosinolate Transport by NPF2.11
The proton-dependent oligopeptide transporter (POT/PTR) family shares a highly conserved E1X1X2E2RFXYY (E1X1X2E2R) motif across all kingdoms of life. This motif is suggested to have a role in proton coupling and active transport in bacterial homologs. For the plant POT/PTR family, also known as the NRT1/PTR family (NPF), little is known about the role of the E1X1X2E2R motif. Moreover, nothing is known about the role of the X1 and X2 residues within the E1X1X2E2R motif. We used NPF2.11—a proton-coupled glucosinolate (GLS) symporter from Arabidopsis thaliana—to investigate the role of the E1X1X2E2K motif variant ...
Source: Plant and Cell Physiology - December 10, 2015 Category: Cytology Authors: Jorgensen, M. E., Olsen, C. E., Geiger, D., Mirza, O., Halkier, B. A., Nour-Eldin, H. H. Tags: Regular Papers Source Type: research
Rice ONAC106 Inhibits Leaf Senescence and Increases Salt Tolerance and Tiller Angle
NAM/ATAF1/ATAF2/CUC2 (NAC) is a plant-specific transcription factor (TF) family, and NACs participate in many diverse processes during the plant life cycle. Several Arabidopsis thaliana NACs have important roles in positively or negatively regulating leaf senescence, but in other plant species, including rice, the senescence-associated NACs (senNACs) remain largely unknown. Here we show that the rice senNAC TF ONAC106 negatively regulates leaf senescence. Leaves of onac106-1D (insertion of the 35S enhancer in the promoter region of the ONAC106 gene) mutants retained their green color under natural senescence and dark-induc...
Source: Plant and Cell Physiology - December 10, 2015 Category: Cytology Authors: Sakuraba, Y., Piao, W., Lim, J.-H., Han, S.-H., Kim, Y.-S., An, G., Paek, N.-C. Tags: Regular Papers Source Type: research
The Relationships between Development and Low Temperature Tolerance in Barley Near Isogenic Lines Differing for Flowering Behavior
Flowering time, vernalization requirement, photoperiod sensitivity and low temperature tolerance are key traits in the Triticeae. We characterized a set of isogenic genetic stocks—representing single and pairwise substitutions of spring alleles at the VRN-H1, VRN-H2 and VRN-H3 loci in a winter barley background—at the structural, functional and phenotypic levels. High density mapping with reference to the barley genome sequence confirmed that in all cases target VRN alleles were present in the near isogenic lines (NILs) and allowed estimates of introgression size (at the genetic and physical levels) and gene co...
Source: Plant and Cell Physiology - December 10, 2015 Category: Cytology Authors: Cuesta-Marcos, A., Munoz-Amatriain, M., Filichkin, T., Karsai, I., Trevaskis, B., Yasuda, S., Hayes, P., Sato, K. Tags: Regular Papers Source Type: research
SIZ1-Dependent Post-Translational Modification by SUMO Modulates Sugar Signaling and Metabolism in Arabidopsis thaliana
Post-translational modification mechanisms function as switches that mediate the balance between optimum growth and the response to environmental stimuli, by regulating the activity of key proteins. SUMO (small ubiquitin-like modifier) attachment, or sumoylation, is a post-translational modification that is essential for the plant stress response, also modulating hormonal circuits to co-ordinate developmental processes. The Arabidopsis SUMO E3 ligase SAP and Miz 1 (SIZ1) is the major SUMO conjugation enhancer in response to stress, and is implicated in several aspects of plant development. Here we report that known SUMO ta...
Source: Plant and Cell Physiology - December 10, 2015 Category: Cytology Authors: Castro, P. H., Verde, N., Lourenco, T., Magalhaes, A. P., Tavares, R. M., Bejarano, E. R., Azevedo, H. Tags: Regular Papers Source Type: research
Enhancement of Thiamin Content in Arabidopsis thaliana by Metabolic Engineering
Thiamin is an essential nutrient in the human diet. Severe thiamin deficiency leads to beriberi, a lethal disease which is common in developing countries. Thiamin biofortification of staple food crops is a possible strategy to alleviate thiamin deficiency-related diseases. In plants, thiamin plays a role in the response to abiotic and biotic stresses, and data from the literature suggest that boosting thiamin content could increase resistance to stresses. Here, we tested an engineering strategy to increase thiamin content in Arabidopsis. Thiamin is composed of a thiazole ring linked to a pyrimidine ring by a methylene brid...
Source: Plant and Cell Physiology - December 10, 2015 Category: Cytology Authors: Dong, W., Stockwell, V. O., Goyer, A. Tags: Regular Papers Source Type: research
Base to Tip and Long-Distance Transport of Sodium in the Root of Common Reed [Phragmites australis (Cav.) Trin. ex Steud.] at Steady State Under Constant High-Salt Conditions
(Source: Plant and Cell Physiology)
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Fujimaki, S., Maruyama, T., Suzui, N., Kawachi, N., Miwa, E., Higuchi, K. Tags: Corrigendum Source Type: research
Persistence and Protection of Mitochondrial DNA in the Generative Cell of Cucumber is Consistent with its Paternal Transmission
Plants predominantly show maternal transmission of mitochondrial DNA (mtDNA). One known exception is cucumber, in which the mtDNA is paternally inherited. However, the mechanisms regulating this unique mode of transmission are unclear. Here we monitored the amounts of mtDNA throughout the development of cucumber microspores into pollen and observed that mtDNA decreases in the vegetative cell, but persists in the generative cell that ultimately produces the sperm cells. We characterized the cucumber homolog (CsDPD1) of the Arabidopsis gene defective in pollen organelle DNA degradation 1 (AtDPD1), which plays a direct role i...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Shen, J., Zhao, J., Bartoszewski, G., Malepszy, S., Havey, M., Chen, J. Tags: Regular Papers Source Type: research
Localization and Quantification of Callose in the Streptophyte Green Algae Zygnema and Klebsormidium: Correlation with Desiccation Tolerance
Freshwater green algae started to colonize terrestrial habitats about 460 million years ago, giving rise to the evolution of land plants. Today, several streptophyte green algae occur in aero-terrestrial habitats with unpredictable fluctuations in water availability, serving as ideal models for investigating desiccation tolerance. We tested the hypothesis that callose, a β-d-1,3-glucan, is incorporated specifically in strained areas of the cell wall due to cellular water loss, implicating a contribution to desiccation tolerance. In the early diverging genus Klebsormidium, callose was drastically increased already afte...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Herburger, K., Holzinger, A. Tags: Regular Papers Source Type: research
Mitochondrial ORFH79 is Essential for Drought and Salt Tolerance in Rice
The mitochondrion is deemed to be one of the most important organelles, and plays an essential role in various biological processes. Nonetheless, the role of mitochondria in response to abiotic stress remains unclear. Here, we report that accumulation of the cytoplasmic male sterility (CMS) protein ORFH79 in the vegetative tissues resulted in the dysfunction of mitochondria with decreased enzymatic activities of respiratory chain complexes, reduced ATP content and even a morphological change of the mitochondria. However, the suppression of orfH79 by overexpressing a fertility restorer gene Rf5, which is targeted to mitocho...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Yu, C., Wang, L., Xu, S., Zeng, Y., He, C., Chen, C., Huang, W., Zhu, Y., Hu, J. Tags: Regular Papers Source Type: research
Functional Characterization of PhapLEAFY, a FLORICAULA/LEAFY Ortholog in Phalaenopsis aphrodite
The plant-specific transcription factor LEAFY (LFY) is considered to be a master regulator of flower development in the model plant, Arabidopsis. This protein plays a dual role in plant growth, integrating signals from the floral inductive pathways and acting as a floral meristem identity gene by activating genes for floral organ development. Although LFY occupies an important position in flower development, the functional divergence of LFY homologs has been demonstrated in several plants including monocots and gymnosperms. In particular, the functional roles of LFY genes from orchid species such as Phalaenopsis that conta...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Jang, S. Tags: Regular Papers Source Type: research
Arabidopsis Intracellular NHX-Type Sodium-Proton Antiporters are Required for Seed Storage Protein Processing
The Arabidopsis intracellular sodium–proton exchanger (NHX) proteins AtNHX5 and AtNHX6 have a well-documented role in plant development, and have been used to improve salt tolerance in a variety of species. Despite evidence that intracellular NHX proteins are important in vacuolar trafficking, the mechanism of this role is poorly understood. Here we show that NHX5 and NHX6 are necessary for processing of the predominant seed storage proteins, and also influence the processing and activity of a vacuolar processing enzyme. Furthermore, we show by yeast two-hybrid and bimolecular fluorescence complementation (BiFC) tech...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Ashnest, J. R., Huynh, D. L., Dragwidge, J. M., Ford, B. A., Gendall, A. R. Tags: Regular Papers Source Type: research
Arabidopsis INCURVATA2 Regulates Salicylic Acid and Abscisic Acid Signaling, and Oxidative Stress Responses
Epigenetic regulatory states can persist through mitosis and meiosis, but the connection between chromatin structure and DNA replication remains unclear. Arabidopsis INCURVATA2 (ICU2) encodes the catalytic subunit of DNA polymerase α, and null alleles of ICU2 have an embryo-lethal phenotype. Analysis of icu2-1, a hypomorphic allele of ICU2, demonstrated that ICU2 functions in chromatin-mediated cellular memory; icu2-1 strongly impairs ICU2 function in the maintenance of repressive epigenetic marks but does not seem to affect ICU2 polymerase activity. To better understand the global function of ICU2 in epigenetic regu...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Micol-Ponce, R., Sanchez-Garcia, A. B., Xu, Q., Barrero, J. M., Micol, J. L., Ponce, M. R. Tags: Regular Papers Source Type: research
Modulation of Root Skewing in Arabidopsis by Apyrases and Extracellular ATP
When plant primary roots grow along a tilted surface that is impenetrable, they can undergo a slanted deviation from the direction of gravity called skewing. Skewing is induced by touch stimuli which the roots experience as they grow along the surface. Touch stimuli also induce the release of extracellular ATP (eATP) into the plant’s extracellular matrix, and two apyrases (NTPDases) in Arabidopsis, APY1 and APY2, can help regulate the concentration of eATP. The primary roots of seedlings overexpressing APY1 show less skewing than wild-type plants. Plants suppressed in their expression of APY1 show more skewing than w...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Yang, X., Wang, B., Farris, B., Clark, G., Roux, S. J. Tags: Regular Papers Source Type: research
The Deconstruction of Pectic Rhamnogalacturonan I Unmasks the Occurrence of a Novel Arabinogalactan Oligosaccharide Epitope
Rhamnogalacturonan I (RGI) is a pectic polysaccharide composed of a backbone of alternating rhamnose and galacturonic acid residues with side chains containing galactose and/or arabinose residues. The structure of these side chains and the degree of substitution of rhamnose residues are extremely variable and depend on species, organs, cell types and developmental stages. Deciphering RGI function requires extending the current set of monoclonal antibodies (mAbs) directed to this polymer. Here, we describe the generation of a new mAb that recognizes a heterogeneous subdomain of RGI. The mAb, INRA-AGI-1, was produced by immu...
Source: Plant and Cell Physiology - November 16, 2015 Category: Cytology Authors: Buffetto, F., Cornuault, V., Rydahl, M. G., Ropartz, D., Alvarado, C., Echasserieau, V., Le Gall, S., Bouchet, B., Tranquet, O., Verhertbruggen, Y., Willats, W. G. T., Knox, J. P., Ralet, M.-C., Guillon, F. Tags: Regular Papers Source Type: research
