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The Journal of Biological Chemistry Aug 2020infects various plants and causes crown gall diseases involving temporal expression of virulence factors. SghA is a newly identified virulence factor enzymatically...
infects various plants and causes crown gall diseases involving temporal expression of virulence factors. SghA is a newly identified virulence factor enzymatically releasing salicylic acid from its glucoside conjugate and controlling plant tumor development. Here, we report the structural basis of SghR, a LacI-type transcription factor highly conserved in family, regulating the expression of SghA and involved in tumorigenesis. We identified and characterized the binding site of SghR on the promoter region of and then determined the crystal structures of apo-SghR, SghR complexed with its operator DNA, and ligand sucrose, respectively. These results provide detailed insights into how SghR recognizes its cognate DNA and shed a mechanistic light on how sucrose attenuates the affinity of SghR with DNA to modulate the expression of SghA. Given the important role of SghR in mediating the signaling cross-talk during infection, our results pave the way for structure-based inducer analog design, which has potential applications for agricultural industry.
Topics: Agrobacterium tumefaciens; Bacterial Proteins; Plant Tumors; Response Elements; Signal Transduction
PubMed: 32651231
DOI: 10.1074/jbc.RA120.012908 -
Journal of Virology Sep 2023Plant viruses induce various disease symptoms that substantially impact agriculture, but the underlying mechanisms of viral disease in plants are poorly understood....
Plant viruses induce various disease symptoms that substantially impact agriculture, but the underlying mechanisms of viral disease in plants are poorly understood. Kobu-sho is a disease in gentian that shows gall formation with ectopic development of lignified cells and vascular tissues such as xylem. Here, we show that a gene fragment of gentian Kobu-sho-associated virus, which is designated as Kobu-sho-inducing factor (), induces gall formation accompanied by ectopic development of lignified cells and xylem-like tissue in . Transgenic gentian expressing exhibited tumorous symptoms, confirming the gall-forming activity of . Surprisingly, expression can also induce differentiation of an additional leaf-like tissue on the abaxial side of veins in normal and gentian leaves. Transcriptome analysis with expressing revealed that activates signaling pathways that regulate xylem development. KOBU protein forms granules and plate-like structures and co-localizes with mRNA splicing factors within the nucleus. Our findings suggest that is a novel pleiotropic virulence factor that stimulates vascular and leaf development. IMPORTANCE While various mechanisms determine disease symptoms in plants depending on virus-host combinations, the details of how plant viruses induce symptoms remain largely unknown in most plant species. Kobu-sho is a disease in gentian that shows gall formation with ectopic development of lignified cells and vascular tissues such as xylem. Our findings demonstrate that a gene fragment of gentian Kobu-sho-associated virus (GKaV), which is designated as Kobu-sho-inducing factor, induces the gall formation accompanied by the ectopic development of lignified cells and xylem-like tissue in . The molecular mechanism by which gentian Kobu-sho-associated virus induces the Kobu-sho symptoms will provide new insight into not only plant-virus interactions but also the regulatory mechanisms underlying vascular and leaf development.
Topics: Arabidopsis; Gene Expression Profiling; Gene Expression Regulation, Plant; Gentiana; Plant Viruses; Nicotiana; Xylem; Virulence Factors; Plant Leaves; Plant Tumors; Signal Transduction; RNA Splicing Factors
PubMed: 37668368
DOI: 10.1128/jvi.00463-23 -
Cell Proliferation Oct 1999There are many arguments for considering a specific fully habituated (auxin and cytokinin-independent) and fully heterotrophic non-organogenic (HNO) sugarbeet callus... (Comparative Study)
Comparative Study Review
Shemin pathway and peroxidase deficiency in a fully habituated and fully heterotrophic non-organogenic sugarbeet callus: an adaptative strategy or the consequence of modified hormonal balances and sensitivities in these cancerous cells? A review and reassessment.
There are many arguments for considering a specific fully habituated (auxin and cytokinin-independent) and fully heterotrophic non-organogenic (HNO) sugarbeet callus cell line as terminating a neoplastic progression, and thus to be made of cancerous cells. The similarities with animal tumour and cancer cells are recalled. All types of habituated tissues examined in the literature share at least three common biochemical characteristics: low apparent peroxidase activity, high content of polyamines (PAs) and low production of ethylene. However, results concerning their auxin and cytokinin levels are not consistent. Peroxidase synthesis in the achlorophyllous HNO callus appears to arise from aminolevulinic acid (ALA) synthesis through the Shemin pathway, commonly used by animals and fungi. This pathway is limited by disturbed nitrogen metabolism that diverts glutamate (directly used for ALA synthesis in green higher plants) from the Kreb's cycle into PA synthesis. There is no argument to suggest that the low ethylene production is caused by a competition with PAs for their common precursor, S-adenosylmethionine. The results we report here indicate modified anabolic and catabolic pathways of auxins and cytokinins but also the possibilities of unusual compounds playing similar roles (dehydrodiconiferyl alcohol glucosides, for instance). A higher turnover of PAs is shown in the HNO callus, which could suggest a role for H2O2 and gamma-aminobutyric acid, products or intermediates in the PA catabolic pathway, as secondary messengers. The habituated cells retain some sensitivity towards exogenous auxins and cytokinins. Their increased sensitivity to PAs and ethylene suggests modified hormonal balances for the control of these actively dividing cells.
Topics: Aminolevulinic Acid; Animals; Biogenic Polyamines; Cell Line; Chenopodiaceae; Cytokinins; Ethylenes; Indoleacetic Acids; Peroxidases; Plant Growth Regulators; Plant Tumors
PubMed: 10619488
DOI: 10.1046/j.1365-2184.1999.3250249.x -
BMC Microbiology Oct 2021The Agrobacterium strain AB2/73 has a unique host range for the induction of crown gall tumors, and contains an exceptionally large, over 500 kbp mega Ti plasmid. We...
BACKGROUND
The Agrobacterium strain AB2/73 has a unique host range for the induction of crown gall tumors, and contains an exceptionally large, over 500 kbp mega Ti plasmid. We used whole genome sequencing to fully characterize and comparatively analyze the complex genome of strain AB2/73, including its Ti plasmid and virulence factors.
RESULTS
We obtained a high-quality, full genomic sequence of AB2/73 by a combination of short-read Illumina sequencing and long-read Nanopore sequencing. The AB2/73 genome has a total size of 7,266,754 bp with 59.5% GC for which 7012 genes (6948 protein coding sequences) are predicted. Phylogenetic and comparative genomics analysis revealed that strain AB2/73 does not belong to the genus Agrobacterium, but to a new species in the genus Rhizobium, which is most related to Rhizobium tropici. In addition to the chromosome, the genome consists of 6 plasmids of which the largest two, of more than 1 Mbp, have chromid-like properties. The mega Ti plasmid is 605 kbp in size and contains two, one of which is incomplete, repABC replication units and thus appears to be a cointegrate consisting of about 175 kbp derived from an unknown Ti plasmid linked to 430 kbp from another large plasmid. In pTiAB2/73 we identified a complete set of virulence genes and two T-DNAs. Besides the previously described T-DNA we found a larger, second T-DNA containing a 6b-like onc gene and the acs gene for agrocinopine synthase. Also we identified two clusters of genes responsible for opine catabolism, including an acc-operon for agrocinopine degradation, and genes putatively involved in ridéopine catabolism. The plasmid also harbours tzs, iaaM and iaaH genes for the biosynthesis of the plant growth regulators cytokinin and auxin.
CONCLUSIONS
The comparative genomics analysis of the high quality genome of strain AB2/73 provided insight into the unusual phylogeny and genetic composition of the limited host range Agrobacterium strain AB2/73. The description of its unique genomic composition and of all the virulence determinants in pTiAB2/73 will be an invaluable tool for further studies into the special host range properties of this bacterium.
Topics: Agrobacterium; DNA, Bacterial; Genes, Bacterial; Genome, Bacterial; Genomics; Host Specificity; Phylogeny; Plant Tumors; Plasmids; Replicon; Rhizobium; Virulence
PubMed: 34711172
DOI: 10.1186/s12866-021-02358-0 -
Cell Cycle (Georgetown, Tex.) Jan 2011
Topics: Animals; Biomarkers, Tumor; Gene Expression Regulation, Plant; Humans; Medical Laboratory Personnel; Plant Proteins; Plant Tumors; Plants; Tumor Protein, Translationally-Controlled 1
PubMed: 21191187
DOI: 10.4161/cc.10.1.14288 -
Molecular Plant Pathology Nov 2019Pantoea agglomerans (Pa), a widespread commensal bacterium, has evolved into a host-specific gall-forming pathogen on gypsophila and beet by acquiring a plasmid...
Pantoea agglomerans (Pa), a widespread commensal bacterium, has evolved into a host-specific gall-forming pathogen on gypsophila and beet by acquiring a plasmid harbouring a type III secretion system (T3SS) and effectors (T3Es). Pantoea agglomerans pv. gypsophilae (Pag) elicits galls on gypsophila and a hypersensitive response on beet, whereas P. agglomerans pv. betae (Pab) elicits galls on beet and gypsophila. HsvG and HsvB are two paralogous T3Es present in both pathovars and act as host-specific transcription activators on gypsophila and beet, respectively. PthG and PseB are major T3Es that contribute to gall development of Pag and Pab, respectively. To establish the minimal combinations of T3Es that are sufficient to elicit gall symptoms, strains of the nonpathogenic bacteria Pseudomonas fluorescens 55, Pa 3-1, Pa 98 and Escherichia coli, transformed with pHIR11 harbouring a T3SS, and the phytopathogenic bacteria Erwinia amylovora, Dickeya solani and Xanthomonas campestris pv. campestris were transformed with the T3Es hsvG, hsvB, pthG and pseB, either individually or in pairs, and used to infect gypsophila and beet. Strikingly, all the tested nonpathogenic and phytopathogenic bacterial strains harbouring hsvG and pthG incited galls on gypsophila, whereas strains harbouring hsvB and pseB, with the exception of E. coli, incited galls on beet.
Topics: Bacterial Proteins; Bacterial Secretion Systems; Beta vulgaris; Host-Pathogen Interactions; Pantoea; Plant Tumors
PubMed: 31368647
DOI: 10.1111/mpp.12860 -
The Plant Cell Apr 2015The biotrophic smut fungus Ustilago maydis infects all aerial organs of maize (Zea mays) and induces tumors in the plant tissues. U. maydis deploys many effector...
The biotrophic smut fungus Ustilago maydis infects all aerial organs of maize (Zea mays) and induces tumors in the plant tissues. U. maydis deploys many effector proteins to manipulate its host. Previously, deletion analysis demonstrated that several effectors have important functions in inducing tumor expansion specifically in maize leaves. Here, we present the functional characterization of the effector See1 (Seedling efficient effector1). See1 is required for the reactivation of plant DNA synthesis, which is crucial for tumor progression in leaf cells. By contrast, See1 does not affect tumor formation in immature tassel floral tissues, where maize cell proliferation occurs independent of fungal infection. See1 interacts with a maize homolog of SGT1 (Suppressor of G2 allele of skp1), a factor acting in cell cycle progression in yeast (Saccharomyces cerevisiae) and an important component of plant and human innate immunity. See1 interferes with the MAPK-triggered phosphorylation of maize SGT1 at a monocot-specific phosphorylation site. We propose that See1 interferes with SGT1 activity, resulting in both modulation of immune responses and reactivation of DNA synthesis in leaf cells. This identifies See1 as a fungal effector that directly and specifically contributes to the formation of leaf tumors in maize.
Topics: Gene Expression Regulation, Plant; Plant Diseases; Plant Proteins; Plant Tumors; Zea mays
PubMed: 25888589
DOI: 10.1105/tpc.114.131086 -
BMC Genomics Dec 2019All eukaryotes share a conserved network of processes regulated by the proteasome and fundamental to growth, development, or perception of the environment, leading to...
BACKGROUND
All eukaryotes share a conserved network of processes regulated by the proteasome and fundamental to growth, development, or perception of the environment, leading to complex but often predictable responses to stress. As a specialized component of the ubiquitin-proteasome system (UPS), the RING finger domain mediates protein-protein interactions and displays considerable versatility in regulating many physiological processes in plants. Many pathogenic organisms co-opt the UPS through RING-type E3 ligases, but little is known about how insects modify these integral networks to generate novel plant phenotypes.
RESULTS
Using a combination of transcriptome sequencing and genome annotation of a grapevine galling species, Daktulosphaira vitifoliae, we identified 138 putatively secretory protein RING-type (SPRINGs) E3 ligases that showed structure and evolutionary signatures of genes under rapid evolution. Moreover, the majority of the SPRINGs were more expressed in the feeding stage than the non-feeding egg stage, in contrast to the non-secretory RING genes. Phylogenetic analyses indicated that the SPRINGs formed clusters, likely resulting from species-specific gene duplication and conforming to features of arthropod host-manipulating (effector) genes. To test the hypothesis that these SPRINGs evolved to manipulate cellular processes within the plant host, we examined SPRING interactions with grapevine proteins using the yeast two-hybrid assay. An insect SPRING interacted with two plant proteins, a cellulose synthase, CSLD5, and a ribosomal protein, RPS4B suggesting secretion reprograms host immune signaling, cell division, and stress response in favor of the insect. Plant UPS gene expression during gall development linked numerous processes to novel organogenesis.
CONCLUSIONS
Taken together, D. vitifoliae SPRINGs represent a novel gene expansion that evolved to interact with Vitis hosts. Thus, a pattern is emerging for gall forming insects to manipulate plant development through UPS targeting.
Topics: Animals; Evolution, Molecular; Gene Duplication; Gene Expression Profiling; Genes, Insect; Hemiptera; Host-Pathogen Interactions; Insect Proteins; Plant Tumors; Proteasome Endopeptidase Complex; Protein Interaction Domains and Motifs; Ubiquitin-Protein Ligases; Vitis
PubMed: 31795978
DOI: 10.1186/s12864-019-6313-x -
Annals of Botany Jan 2018Understanding to what extent parasites affect host fitness is a focus of research on ecological interactions. Fungal parasites usually affect the functions of vascular...
BACKGROUND AND AIMS
Understanding to what extent parasites affect host fitness is a focus of research on ecological interactions. Fungal parasites usually affect the functions of vascular plants. However, parasitic interactions comprising effects of fungal parasites on the fitness of lichen hosts are less well known. This study assesses the effects of the abundance of two highly specialized gall-forming fungi on growth of their two respective lichen hosts and tests whether these fungal parasites reduce lichen fitness.
METHODS
The relative biomass and thallus area growth rates, and change in specific thallus mass of Lobaria pulmonaria and L. scrobiculata were compared between lichens with and without galls of the lichenicolous fungi Plectocarpon lichenum and P. scrobiculatae, cultivated in a growth chamber for 14 d. By estimating the thallus area occupied by the galls, it was also assessed whether growth rates varied with effective photosynthetic lichen surface area.
KEY RESULTS
Plectocarpon galls significantly reduced relative growth rates of the lichen hosts. Growth rates decreased with increasing cover of parasitic galls. The presence of Plectocarpon-galls per se, not the reduced photosynthetic thallus surface due to gall induction, reduced relative growth rates in infected hosts. Specific thallus mass in the hosts changed in species-specific ways.
CONCLUSIONS
This study shows that specialized fungal parasites can reduce lichen fitness by reducing their growth rates. Higher parasite fitness correlated with lower host fitness, supporting the view that these associations are antagonistic. By reducing hosts' growth rates, these parasites in their symptomatic life stage may affect important lichen functions. This fungal parasite-lichen study widens the knowledge on the ecological effects of parasitism on autotrophic hosts and expands our understanding of parasitic interactions across overlooked taxonomic groups.
Topics: Ascomycota; Lichens; Photosynthesis; Plant Tumors
PubMed: 29155927
DOI: 10.1093/aob/mcx124 -
Plant Physiology Nov 2003
Topics: Agrobacterium tumefaciens; DNA, Bacterial; Plant Cells; Plant Tumors; Plants; Transformation, Genetic
PubMed: 14612580
DOI: 10.1104/pp.103.032821