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Sonnewald S, Priller JPR, Schuster J, Glickmann E, Hajirezaei MR, Siebig S, Mudgett MB, Sonnewald U. Regulation of cell wall-bound invertase in pepper leaves by Xanthomonas campestris pv. vesicatoria type three effectors. PLoS One 2012; 7:e51763. [PMID: 23272161 PMCID: PMC3522709 DOI: 10.1371/journal.pone.0051763] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 11/06/2012] [Indexed: 12/29/2022] Open
Abstract
Xanthomonas campestris pv. vesicatoria (Xcv) possess a type 3 secretion system (T3SS) to deliver effector proteins into its Solanaceous host plants. These proteins are involved in suppression of plant defense and in reprogramming of plant metabolism to favour bacterial propagation. There is increasing evidence that hexoses contribute to defense responses. They act as substrates for metabolic processes and as metabolic semaphores to regulate gene expression. Especially an increase in the apoplastic hexose-to-sucrose ratio has been suggested to strengthen plant defense. This shift is brought about by the activity of cell wall-bound invertase (cw-Inv). We examined the possibility that Xcv may employ type 3 effector (T3E) proteins to suppress cw-Inv activity during infection. Indeed, pepper leaves infected with a T3SS-deficient Xcv strain showed a higher level of cw-Inv mRNA and enzyme activity relative to Xcv wild type infected leaves. Higher cw-Inv activity was paralleled by an increase in hexoses and mRNA abundance for the pathogenesis-related gene PRQ. These results suggest that Xcv suppresses cw-Inv activity in a T3SS-dependent manner, most likely to prevent sugar-mediated defense signals. To identify Xcv T3Es that regulate cw-Inv activity, a screen was performed with eighteen Xcv strains, each deficient in an individual T3E. Seven Xcv T3E deletion strains caused a significant change in cw-Inv activity compared to Xcv wild type. Among them, Xcv lacking the xopB gene (Xcv ΔxopB) caused the most prominent increase in cw-Inv activity. Deletion of xopB increased the mRNA abundance of PRQ in Xcv ΔxopB-infected pepper leaves, but not of Pti5 and Acre31, two PAMP-triggered immunity markers. Inducible expression of XopB in transgenic tobacco inhibited Xcv-mediated induction of cw-Inv activity observed in wild type plants and resulted in severe developmental phenotypes. Together, these data suggest that XopB interferes with cw-Inv activity in planta to suppress sugar-enhanced defense responses during Xcv infection.
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Affiliation(s)
- Sophia Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
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Rizza S, Conesa A, Juarez J, Catara A, Navarro L, Duran-Vila N, Ancillo G. Microarray analysis of Etrog citron (Citrus medica L.) reveals changes in chloroplast, cell wall, peroxidase and symporter activities in response to viroid infection. MOLECULAR PLANT PATHOLOGY 2012; 13:852-64. [PMID: 22420919 PMCID: PMC6638686 DOI: 10.1111/j.1364-3703.2012.00794.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Viroids are small (246-401 nucleotides), single-stranded, circular RNA molecules that infect several crop plants and can cause diseases of economic importance. Citrus are the hosts in which the largest number of viroids have been identified. Citrus exocortis viroid (CEVd), the causal agent of citrus exocortis disease, induces considerable losses in citrus crops. Changes in the gene expression profile during the early (pre-symptomatic) and late (post-symptomatic) stages of Etrog citron infected with CEVd were investigated using a citrus cDNA microarray. MaSigPro analysis was performed and, on the basis of gene expression profiles as a function of the time after infection, the differentially expressed genes were classified into five clusters. FatiScan analysis revealed significant enrichment of functional categories for each cluster, indicating that viroid infection triggers important changes in chloroplast, cell wall, peroxidase and symporter activities.
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Affiliation(s)
- Serena Rizza
- Department of Phytosanitary Sciences and Technologies-University of Catania, Via S. Sofia 102, 95123 Catania, Italy
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Schwachtje J, Karojet S, Thormählen I, Bernholz C, Kunz S, Brouwer S, Schwochow M, Köhl K, van Dongen JT. A naturally associated rhizobacterium of Arabidopsis thaliana induces a starvation-like transcriptional response while promoting growth. PLoS One 2011; 6:e29382. [PMID: 22216267 PMCID: PMC3247267 DOI: 10.1371/journal.pone.0029382] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/28/2011] [Indexed: 12/29/2022] Open
Abstract
Plant growth promotion by rhizobacteria is a known phenomenon but the underlying mechanisms are poorly understood. We searched for plant growth-promoting rhizobacteria that are naturally associated with Arabidopsis thaliana to investigate the molecular mechanisms that are involved in plant growth-promotion. We isolated a Pseudomonas bacterium (Pseudomonas sp. G62) from roots of field-grown Arabidopsis plants that has not been described previously and analyzed its effect on plant growth, gene expression and the level of sugars and amino acids in the host plant. Inoculation with Pseudomonas sp. G62 promoted plant growth under various growth conditions. Microarray analysis revealed rapid changes in transcript levels of genes annotated to energy-, sugar- and cell wall metabolism in plants 6 h after root inoculation with P. sp. G62. The expression of several of these genes remained stable over weeks, but appeared differentially regulated in roots and shoots. The global gene expression profile observed after inoculation with P. sp. G62 showed a striking resemblance with previously described carbohydrate starvation experiments, although plants were not depleted from soluble sugars, and even showed a slight increase of the sucrose level in roots 5 weeks after inoculation. We suggest that the starvation-like transcriptional phenotype - while steady state sucrose levels are not reduced - is induced by a yet unknown signal from the bacterium that simulates sugar starvation. We discuss the potential effects of the sugar starvation signal on plant growth promotion.
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Affiliation(s)
- Jens Schwachtje
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- * E-mail: (JS); (JTvD)
| | - Silke Karojet
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Ina Thormählen
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Carolin Bernholz
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Sabine Kunz
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Stephan Brouwer
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Melanie Schwochow
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Karin Köhl
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Joost T. van Dongen
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
- * E-mail: (JS); (JTvD)
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Molitor A, Zajic D, Voll LM, Pons-K Hnemann J, Samans B, Kogel KH, Waller F. Barley leaf transcriptome and metabolite analysis reveals new aspects of compatibility and Piriformospora indica-mediated systemic induced resistance to powdery mildew. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:1427-39. [PMID: 21830949 DOI: 10.1094/mpmi-06-11-0177] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Colonization of barley roots with the basidiomycete fungus Piriformospora indica (Sebacinales) induces systemic resistance against the biotrophic leaf pathogen Blumeria graminis f. sp. hordei (B. graminis). To identify genes involved in this mycorrhiza-induced systemic resistance, we compared the leaf transcriptome of P. indica-colonized and noncolonized barley plants 12, 24, and 96 h after challenge with a virulent race of B. graminis. The leaf pathogen induced specific gene sets (e.g., LRR receptor kinases and WRKY transcription factors) at 12 h postinoculation (hpi) (prepenetration phase) and vesicle-localized gene products 24 hpi (haustorium establishment). Metabolic analysis revealed a progressing shift of steady state contents of the intermediates glucose-1-phosphate, uridinediphosphate-glucose, and phosphoenolpyruvate 24 and 96 hpi, indicating that B. graminis shifts central carbohydrate metabolism in favor of sucrose biosynthesis. Both B. graminis and P. indica increased glutamine and alanine contents, whereas substrates for starch and nitrogen assimilation (adenosinediphosphate- glucose and oxoglutarate) decreased. In plants that were more B. graminis resistant due to P. indica root colonization, 22 transcripts, including those of pathogenesis-related genes and genes encoding heat-shock proteins, were differentially expressed ?twofold in leaves after B. graminis inoculation compared with non-mycorrhized plants. Detailed expression analysis revealed a faster induction after B. graminis inoculation between 8 and 16 hpi, suggesting that priming of these genes is an important mechanism of P. indica-induced systemic disease resistance.
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Kyseláková H, Prokopová J, Nauš J, Novák O, Navrátil M, Safářová D, Spundová M, Ilík P. Photosynthetic alterations of pea leaves infected systemically by pea enation mosaic virus: A coordinated decrease in efficiencies of CO(2) assimilation and photosystem II photochemistry. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2011; 49:1279-89. [PMID: 22000051 DOI: 10.1016/j.plaphy.2011.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/08/2011] [Indexed: 05/04/2023]
Abstract
We have investigated photosynthetic changes of fully expanded pea leaves infected systemically by pea enation mosaic virus (PEMV) that often attacks legumes particularly in northern temperate regions. A typical compatible virus-host interaction was monitored during 40 post-inoculation days (dpi). An initial PEMV-induced decrease in photosynthetic CO(2) assimilation was detected at 15 dpi, when the virus appeared in the measured leaves. This decrease was not induced by stomata closure and corresponded with a decrease in the efficiency of photosystem II photochemistry (Φ(PSII)). Despite of a slight impairment of oxygen evolution at this stage, PSII function was not primarily responsible for the decrease in Φ(PSII). Chlorophyll fluorescence imaging revealed that Φ(PSII) started to decrease from the leaf tip to the base. More pronounced symptoms of PEMV disease appeared at later stages, when a typical mosaic and enations appeared in the infected leaves and oxidative damage of cell membranes was detected. From 30 dpi, a degradation of photosynthetic pigments accelerated, stomata were closing and corresponding pronounced decline in CO(2) assimilation was observed. A concomitant photoprotective responses, i.e. an increase in non-photochemical quenching and accumulation of de-epoxidized xanthophylls, were also detected. Interestingly, alternative electron sinks in chloroplasts were not stimulated by PEMV infection, which is in contradiction to earlier reports dealing with virus-induced plant stresses. The presented results show that the PEMV-induced alterations in mature pea leaves accelerated leaf senescence during which a decrease in Φ(PSII) took place in coordinated manner with an inhibition of CO(2) assimilation.
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Affiliation(s)
- Helena Kyseláková
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Biophysics, Faculty of Science, Palacký University, Šlechtitelů 11, Olomouc CZ-78371, Czech Republic
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56
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Voll LM, Horst RJ, Voitsik AM, Zajic D, Samans B, Pons-Kühnemann J, Doehlemann G, Münch S, Wahl R, Molitor A, Hofmann J, Schmiedl A, Waller F, Deising HB, Kahmann R, Kämper J, Kogel KH, Sonnewald U. Common Motifs in the Response of Cereal Primary Metabolism to Fungal Pathogens are not Based on Similar Transcriptional Reprogramming. FRONTIERS IN PLANT SCIENCE 2011; 2:39. [PMID: 22645534 PMCID: PMC3355734 DOI: 10.3389/fpls.2011.00039] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 08/01/2011] [Indexed: 05/05/2023]
Abstract
During compatible interactions with their host plants, biotrophic plant-pathogens subvert host metabolism to ensure the sustained provision of nutrient assimilates by the colonized host cells. To investigate, whether common motifs can be revealed in the response of primary carbon and nitrogen metabolism toward colonization with biotrophic fungi in cereal leaves, we have conducted a combined metabolome and transcriptome study of three quite divergent pathosystems, the barley powdery mildew fungus (Blumeria graminis f.sp. hordei), the corn smut fungus Ustilago maydis, and the maize anthracnose fungus Colletotrichum graminicola, the latter being a hemibiotroph that only exhibits an initial biotrophic phase during its establishment. Based on the analysis of 42 water-soluble metabolites, we were able to separate early biotrophic from late biotrophic interactions by hierarchical cluster analysis and principal component analysis, irrespective of the plant host. Interestingly, the corresponding transcriptome dataset could not discriminate between these stages of biotrophy, irrespective, of whether transcript data for genes of central metabolism or the entire transcriptome dataset was used. Strong differences in the transcriptional regulation of photosynthesis, glycolysis, the TCA cycle, lipid biosynthesis, and cell wall metabolism were observed between the pathosystems. However, increased contents of Gln, Asn, and glucose as well as diminished contents of PEP and 3-PGA were common to early post-penetration stages of all interactions. On the transcriptional level, genes of the TCA cycle, nucleotide energy metabolism and amino acid biosynthesis exhibited consistent trends among the compared biotrophic interactions, identifying the requirement for metabolic energy and the rearrangement of amino acid pools as common transcriptional motifs during early biotrophy. Both metabolome and transcript data were employed to generate models of leaf primary metabolism during early biotrophy for the three investigated interactions.
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Affiliation(s)
- Lars Matthias Voll
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Robin Jonathan Horst
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Anna-Maria Voitsik
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Doreen Zajic
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Birgit Samans
- Institute of Biometry and Population Genetics, Justus Liebig UniversityGiessen, Germany
- Research Center for BioSystems, Land Use and Nutrition, Justus Liebig UniversityGiessen, Germany
| | - Jörn Pons-Kühnemann
- Institute of Biometry and Population Genetics, Justus Liebig UniversityGiessen, Germany
- Research Center for BioSystems, Land Use and Nutrition, Justus Liebig UniversityGiessen, Germany
| | | | - Steffen Münch
- Faculty of Agricultural and Nutritional Sciences, Phytopathology and Plant Protection, Martin-Luther-University Halle-WittenbergHalle, Germany
| | - Ramon Wahl
- Department of Genetics, Institute of Applied Biosciences, University of KarlsruheKarlsruhe, Germany
| | - Alexandra Molitor
- Research Center for BioSystems, Land Use and Nutrition, Justus Liebig UniversityGiessen, Germany
- Institute of Phytopathology and Applied Zoology, Justus Liebig UniversityGiessen, Germany
| | - Jörg Hofmann
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Alfred Schmiedl
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
| | - Frank Waller
- Research Center for BioSystems, Land Use and Nutrition, Justus Liebig UniversityGiessen, Germany
- Institute of Phytopathology and Applied Zoology, Justus Liebig UniversityGiessen, Germany
| | - Holger Bruno Deising
- Faculty of Agricultural and Nutritional Sciences, Phytopathology and Plant Protection, Martin-Luther-University Halle-WittenbergHalle, Germany
| | - Regine Kahmann
- Max Planck Institute for Terrestrial MicrobiologyMarburg, Germany
| | - Jörg Kämper
- Department of Genetics, Institute of Applied Biosciences, University of KarlsruheKarlsruhe, Germany
| | - Karl-Heinz Kogel
- Research Center for BioSystems, Land Use and Nutrition, Justus Liebig UniversityGiessen, Germany
- Institute of Phytopathology and Applied Zoology, Justus Liebig UniversityGiessen, Germany
| | - Uwe Sonnewald
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-NurembergErlangen, Germany
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Madala NE, Molinaro A, Dubery IA. Distinct carbohydrate and lipid-based molecular patterns within lipopolysaccharides from Burkholderia cepacia contribute to defense-associated differential gene expression in Arabidopsis thaliana. Innate Immun 2011; 18:140-54. [PMID: 21733976 DOI: 10.1177/1753425910392609] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Lipopolysaccharides are structural components within the cell walls of Gram-negative bacteria. The LPSs as microbe-associated molecular pattern (MAMP) molecules can trigger defense-related responses involved in MAMP-triggered immunity and basal resistance in plants, presumably from an initial perception event. LPS from Burkholderia cepacia as well as two fragments, the glycolipid, lipid A and the polysaccharide (OPS-core) chain, were used to treat Arabidopsis thaliana seedlings to evaluate the eliciting activities of the individual LPS sub-domains by means of Annealing Control Primer-based Differential Display transcript profiling. Genes found to be up-regulated encode for proteins involved in signal perception and transduction, transcriptional regulation and defense - and stress responses. Furthermore, genes encoding proteins involved in chaperoning, secretion, protein-protein interactions and protein degradation were differentially expressed. It is concluded that intact LPS, as well as the two sub-components, induced the expression of a broad range of genes associated with perception and defense as well as metabolic reprogramming of cellular activities in support of immunity and basal resistance. Whilst the lipid A and OPS moieties were able to up-regulate sub-sets of defense-associated genes over the same spectrum of categories as intact LPS, the up-regulation observed with intact LPS was the more comprehensive, suggesting that the lipid A and glycan molecular patterns of the molecule act as partial agonists, but that the intact LPS structure is required for full agonist activity.
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Affiliation(s)
- Ntakadzeni E Madala
- Department of Biochemistry, University of Johannesburg, Johannesburg, South Africa
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58
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Pathuri IP, Reitberger IE, Hückelhoven R, Proels RK. Alcohol dehydrogenase 1 of barley modulates susceptibility to the parasitic fungus Blumeria graminis f.sp. hordei. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:3449-57. [PMID: 21339386 PMCID: PMC3130169 DOI: 10.1093/jxb/err017] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 01/08/2011] [Accepted: 01/17/2011] [Indexed: 05/20/2023]
Abstract
Plant primary energy metabolism is profoundly reorganized under biotic stress conditions and there is increasing evidence for a role for the fermentative pathway in biotic interactions. However, the mechanisms regulating metabolic reprogramming are not well understood despite its critical function in the biotic stress response. Here the function of alcohol dehydrogenase (ADH) in the interaction of barley with the parasitic fungus Blumeria graminis f.sp. hordei (Bgh) is addressed. Challenge of susceptible barley leaves with Bgh resulted in transcriptional activation of HvADH1 and an induction of ADH enzyme activity starting 24 h after infection and reaching a clear-cut effect 4 d after infection. This increase in ADH enzyme activity was not observed in the resistant near-isogenic mlo5 line. Moreover, an induction of ADH enzyme activity by Bgh was enhanced in the presence of sucrose in hydroponically grown seedlings. Transient knock-down or overexpression of HvADH1 in barley epidermal cells mediated a decrease or increase in the penetration success of Bgh, respectively. Inhibition of ADH activity by pyrazole resulted in a delay in symptoms. The pyrazole effect could be overcome by adding glucose to the incubation medium, pinpointing a nutritional effect of ADH in the barley-Bgh interaction. Taken together, misexpression of pathogen-inducible HvADH1 or variation of ADH activity modulates the pathogen response of barley to the biotrophic fungal parasite Bgh. In this way, ADH knock-down/inhibition results in reduced fungal success. The possibility is discussed that ADH activity supports biotrophy by maintaining glycolytic metabolism in pathogen-stressed barley.
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59
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Zhao D, Glynn NC, Glaz B, Comstock JC, Sood S. Orange Rust Effects on Leaf Photosynthesis and Related Characters of Sugarcane. PLANT DISEASE 2011; 95:640-647. [PMID: 30731934 DOI: 10.1094/pdis-10-10-0762] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Orange rust of sugarcane (Saccharum spp. hybrids), caused by Puccinia kuehnii, is a relatively new disease in the Western Hemisphere that substantially reduces yields in susceptible sugarcane genotypes. The objective of this study was to determine the physiological mechanisms of orange rust-induced reductions in sugarcane growth and yield by quantifying effects of the disease on leaf SPAD index (an indication of leaf chlorophyll content), net photosynthetic rate, dark respiration, maximum quantum yield of CO2 assimilation, carbon fixation efficiency, and the relationships between these leaf photosynthetic components and rust disease ratings. Plants growing in pots were inoculated with the orange rust pathogen using a leaf whorl inoculation method. A disease rating was assigned using a scale from 0 to 4 with intervals of 0.5. At disease ratings ≥2, the rust-infected leaf portion of inoculated plants showed significant reductions in SPAD index, maximum quantum yield, carbon fixation efficiency, stomatal conductance, leaf transpiration rate, and net photosynthetic rate; but the rusted portion of the infected leaves had increased intercellular CO2 concentration and leaf dark respiration rate. Although leaf SPAD index, photosynthetic rate, stomatal conductance, and transpiration rate at the rust-infected portion decreased linearly with increased rust rating, the effect of orange rust on photosynthetic rate was much greater than that on stomatal conductance and transpiration. Unlike earlier reports on other crops, reduction in leaf photosynthesis by orange rust under low light was greater than that under high light conditions. These results help improve the understanding of orange rust etiology and physiological bases of sugarcane yield loss caused by orange rust.
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Affiliation(s)
- Duli Zhao
- USDA-ARS, Sugarcane Field Station, 12990 U.S. Highway 441 North, Canal Point, FL 33438
| | - Neil C Glynn
- USDA-ARS, Sugarcane Field Station, 12990 U.S. Highway 441 North, Canal Point, FL 33438
| | - Barry Glaz
- USDA-ARS, Sugarcane Field Station, 12990 U.S. Highway 441 North, Canal Point, FL 33438
| | - Jack C Comstock
- USDA-ARS, Sugarcane Field Station, 12990 U.S. Highway 441 North, Canal Point, FL 33438
| | - Sushma Sood
- USDA-ARS, Sugarcane Field Station, 12990 U.S. Highway 441 North, Canal Point, FL 33438
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60
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Siemens J, González MC, Wolf S, Hofmann C, Greiner S, DU Y, Rausch T, Roitsch T, Ludwig-Müller J. Extracellular invertase is involved in the regulation of clubroot disease in Arabidopsis thaliana. MOLECULAR PLANT PATHOLOGY 2011; 12:247-62. [PMID: 21355997 PMCID: PMC6640435 DOI: 10.1111/j.1364-3703.2010.00667.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Clubroot disease of Brassicaceae is caused by an obligate biotrophic protist, Plasmodiophora brassicae. During root gall development, a strong sink for assimilates is developed. Among other genes involved in sucrose and starch synthesis and degradation, the increased expression of invertases has been observed in a microarray experiment, and invertase and invertase inhibitor expression was confirmed using promoter::GUS lines of Arabidopsis thaliana. A functional approach demonstrates that invertases are important for gall development. Different transgenic lines expressing an invertase inhibitor under the control of two root-specific promoters, Pyk10 and CrypticT80, which results in the reduction of invertase activity, showed clearly reduced clubroot symptoms in root tissue with highest promoter expression, whereas hypocotyl galls developed normally. These results present the first evidence that invertases are important factors during gall development, most probably in supplying sugars to the pathogen. In addition, root-specific repression of invertase activity could be used as a tool to reduce clubroot symptoms.
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Affiliation(s)
- Johannes Siemens
- Department of Biology, Technische Universität Dresden, Zellescher Weg 20b, D-01062 Dresden, Germany
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61
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Morkunas I, Narożna D, Nowak W, Samardakiewicz S, Remlein-Starosta D. Cross-talk interactions of sucrose and Fusarium oxysporum in the phenylpropanoid pathway and the accumulation and localization of flavonoids in embryo axes of yellow lupine. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:424-33. [PMID: 21056513 DOI: 10.1016/j.jplph.2010.08.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 08/06/2010] [Accepted: 08/09/2010] [Indexed: 05/21/2023]
Abstract
This study investigated the effects of cross-talk interactions of sucrose and infection caused by a pathogenic fungus Fusarium oxysporum f.sp. lupini on the regulation of the phenylpropanoid pathway, i.e. the level of expression of genes encoding enzymes participating in flavonoid biosynthesis, as well as cell location and accumulation of these compounds in embryo axes of Lupinus luteus L. cv. Polo. Embryo axes, both non-inoculated and inoculated, were cultured for 96h on Heller medium with 60mM sucrose (+Sn and +Si) or without it (-Sn and -Si). Real-time RT-PCR to assess expression levels of the flavonoid biosynthetic genes, phenylalanine ammonialyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI) and isoflavone synthase (IFS) were used. Sucrose alone strongly stimulated the expression of these genes. There was a very high expression level of these genes in +Si embryo axes in the early phase of infection. Signal amplification by sucrose and the infection was most intense in the 48-h +Si axes, resulting in the highest level of expression of flavonoid biosynthetic genes. In -Si tissues, the expression level of these genes increased at 48 and 72h after inoculation relative to 24h; however, the relative level of expression was much lower than in +Si axes, except at 72h for PAL and CHS.Moreover, at 48h of culture, considerably higher activity of CHI (EC 5.5.1.6) was observed in axes with a high level of sucrose than in those with a sucrose deficit. CHI activity in +Si axes at 48 and 96h post-inoculation was over 1.5 and 2 times higher than that in +Sn axes, as well as higher than in -Si axes.Observations of yellow lupine embryo axes under a confocal microscope showed an increased post-infection accumulation of flavonoids, particularly in cells of embryo axes infected with F. oxysporum and cultured on a medium containing sucrose (+Si). Up to 48h post-infection in +Si axes, a very intensive emission of green fluorescence was observed, indicating high accumulation of these compounds in whole cells. Moreover, a nuclear location of flavonoids was recorded in cells. Strong staining of flavonoid end products in +Si embryo axes was consistent with the expression of PAL, CHS, CHI and IFS.These results indicate that, in the early phase of infection, the flavonoid biosynthesis pathway is considerably enhanced in yellow lupine embryo axes as a strong signal amplification effect of sucrose and the pathogenic fungus F. oxysporum.
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Affiliation(s)
- Iwona Morkunas
- Department of Plant Physiology, Poznan University of Life Sciences, Wołyńska 35, 60-637 Poznań, Poland.
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62
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Horst RJ, Doehlemann G, Wahl R, Hofmann J, Schmiedl A, Kahmann R, Kämper J, Voll LM. A model of Ustilago maydis leaf tumor metabolism. PLANT SIGNALING & BEHAVIOR 2010; 5:1446-9. [PMID: 21051942 PMCID: PMC3115251 DOI: 10.4161/psb.5.11.13360] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Extensive progress has been made in the last years in unraveling molecular mechanisms of plant-pathogen interactions. Although the main research focus lies on defense and counter-defense mechanisms, some plant-pathogen interactions have been characterized on the physiological level. Only a few studies have focused on the nutrient acquisition strategies of phytopathogens. In a previous study, we analyzed how local infection of maize leaves by the tumor-inducing fungus Ustilago maydis affects whole plant physiology and were able to show that carbon and nitrogen assimilates are rerouted to the tumor. While the sink strength of infected emerging young leaves increases with tumor development, systemic source leaves exhibit elevated export of assimilates and delayed senescence to compensate for the altered sink-source balance. Here we provide new experimental data on the metabolization of these assimilates in the tumor and propose a model on their utilization in the infected tissue.
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Affiliation(s)
- Robin J Horst
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Division of Biochemistry, Erlangen, Germany
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63
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Behr M, Humbeck K, Hause G, Deising HB, Wirsel SGR. The hemibiotroph Colletotrichum graminicola locally induces photosynthetically active green islands but globally accelerates senescence on aging maize leaves. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:879-92. [PMID: 20521951 DOI: 10.1094/mpmi-23-7-0879] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Typically, pathogenesis of the hemibiotroph Colletotrichum graminicola and defense responses of its host, Zea mays, are studied on young leaves. Equivalent studies have not been performed with leaves undergoing senescence, a situation that is relevant in the field. We discovered that, in contrast to anthracnose symptoms formed on young and mature leaves, green islands reminiscent of those known from obligate biotrophs were formed on senescing leaves. Microscopy revealed that the fungus grew in both symptoms from the epidermis towards the bundle sheath. In green islands, tissues remained intact for an extended time period. Imaging PAM (pulse-amplitude-modulation) fluorescence analyses revealed that photosynthesis is transiently maintained at green islands but declined in tissue surrounding the infection. In younger leaves however, photosynthesis was reduced only at infection sites. Support for the local modification of host physiology came from quantitative reverse transcription-polymerase chain reaction analyzing gene expression at high spatial resolution. Decreased transcript levels of the senescence markers see1 and ccp1 corroborated a pathogen-induced delay of senescence. Expression of several genes encoding proteins involved in photosynthesis was strongly reduced by infection. In contrast, transcript levels of incw1, encoding a cell-wall invertase, were increased 70-fold at green islands, suggesting that C. graminicola induced carbon sinks in senescing tissue.
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Affiliation(s)
- Michael Behr
- Institut für Agrar- und Ernährungswissenschaften, Naturwissenschaftlische Fakultät III, Martin-Luther Universität Halle-Wittenberg, Halle (Saale), Germany
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64
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Zavaliev R, Sagi G, Gera A, Epel BL. The constitutive expression of Arabidopsis plasmodesmal-associated class 1 reversibly glycosylated polypeptide impairs plant development and virus spread. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:131-42. [PMID: 19887501 PMCID: PMC2791124 DOI: 10.1093/jxb/erp301] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Accepted: 09/03/2009] [Indexed: 05/17/2023]
Abstract
Arabidopsis class 1 reversibly glycosylated polypeptides (C1RGPs) were shown to be plasmodesmal-associated proteins. Transgenic tobacco (Nicotiana tabacum) plants constitutively expressing GFP tagged AtRGP2 under the control of the CaMV 35S promoter are stunted, have a rosette-like growth pattern, and in source leaves exhibit strong chlorosis, increased photoassimilate retention and starch accumulation that results in elevated leaf specific fresh and dry weights. Basal callose levels around plasmodesmata (Pd) of leaf epidermal cells in transgenic plants are higher than in WT. Such a phenotype is characteristic of virus-infected plants and some transgenic plants expressing Pd-associated viral movement proteins (MP). The local spread of Tobacco mosaic virus (TMV) is inhibited in AtRGP2:GFP transgenics compared to WT. Taken together these observations suggest that overexpression of the AtRGP2:GFP leads to a reduction in Pd permeability to photoassimilate, thus lowering the normal rate of translocation from source leaves to sink organs. Such a reduction may also inhibit the local cell-to-cell spread of viruses in transgenic plants. The observed reduction in Pd permeability could be due to a partial Pd occlusion caused either by the accumulation of AtRGP2:GFP fusion in Pd, and/or by constriction of Pd by the excessive callose accumulation.
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Affiliation(s)
- Raul Zavaliev
- Department of Plant Sciences, George S Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Guy Sagi
- Department of Plant Sciences, George S Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | - Abed Gera
- Department of Plant Pathology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Bernard L. Epel
- Department of Plant Sciences, George S Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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65
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Zurbriggen MD, Carrillo N, Tognetti VB, Melzer M, Peisker M, Hause B, Hajirezaei MR. Chloroplast-generated reactive oxygen species play a major role in localized cell death during the non-host interaction between tobacco and Xanthomonas campestris pv. vesicatoria. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 60:962-73. [PMID: 19719480 DOI: 10.1111/j.1365-313x.2009.04010.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Attempted infection of plants by pathogens elicits a complex defensive response. In many non-host and incompatible host interactions it includes the induction of defence-associated genes and a form of localized cell death (LCD), purportedly designed to restrict pathogen advance, collectively known as the hypersensitive response (HR). It is preceded by an oxidative burst, generating reactive oxygen species (ROS) that are proposed to cue subsequent deployment of the HR, although neither the origin nor the precise role played by ROS in the execution of this response are completely understood. We used tobacco plants expressing cyanobacterial flavodoxin to address these questions. Flavodoxin is an electron shuttle present in prokaryotes and algae that, when expressed in chloroplasts, specifically prevents ROS formation in plastids during abiotic stress episodes. Infiltration of tobacco wild-type leaves with high titres of Xanthomonas campestris pv. vesicatoria (Xcv), a non-host pathogen, resulted in ROS accumulation in chloroplasts, followed by the appearance of localized lesions typical of the HR. In contrast, chloroplast ROS build-up and LCD were significantly reduced in Xcv-inoculated plants expressing plastid-targeted flavodoxin. Metabolic routes normally inhibited by pathogens were protected in the transformants, whereas other aspects of the HR, including the induction of defence-associated genes and synthesis of salicylic and jasmonic acid, proceeded as in inoculated wild-type plants. Therefore, ROS generated in chloroplasts during this non-host interaction are essential for the progress of LCD, but do not contribute to the induction of pathogenesis-related genes or other signalling components of the response.
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Affiliation(s)
- Matias D Zurbriggen
- Instituto de Biología Molecular y Celular de Rosario (IBR, UNR/CONICET), División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
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66
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Judelson HS, Tani S, Narayan RD. Metabolic adaptation of Phytophthora infestans during growth on leaves, tubers and artificial media. MOLECULAR PLANT PATHOLOGY 2009; 10:843-55. [PMID: 19849790 PMCID: PMC6640522 DOI: 10.1111/j.1364-3703.2009.00570.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Efficient nutrient acquisition is critical to the fitness of plant pathogens. To address how the late blight agent Phytophthora infestans adapts to nutrients offered by its hosts, genes in glycolytic, gluconeogenic and amino acid pathways were mined from its genome and their expression in different plant tissues and artificial media was measured. Evidence for conventional glycolytic and gluconeogenic processes was obtained, although several steps involved pyrophosphate-linked transformations which are uncommon in eukaryotes. In media manipulation studies, nearly all genes in the pathways were subject to strong transcriptional control. However in rye-sucrose media, tomato leaflets, potato tubers and, at both early and late stages of infection, most glycolytic genes were expressed similarly, which indicated that each plant tissue presented a nutrient-rich environment. Biochemical analyses also demonstrated that sporulation occurred from host material in which sugars were abundant, with fructose and glucose increasing at the expense of sucrose late in the disease cycle. The expression of only a few genes changed late in infection, with the most notable example being lower invertase levels in the sucrose-reduced leaves. Interestingly, most gluconeogenic genes were up-regulated in tubers compared with other tissues. Rather than reflecting a starvation response, this probably reveals the role of such enzymes in converting carbon skeletons from the abundant free amino acids of tubers into citric acid cycle and glycolysis intermediates, as genes involved in amino acid catabolism were also more highly expressed in tubers. The corresponding enzymes also displayed higher activities in defined media when amino acids were abundant, as in tubers.
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Affiliation(s)
- Howard S Judelson
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA.
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67
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Scholes JD, Rolfe SA. Chlorophyll fluorescence imaging as tool for understanding the impact of fungal diseases on plant performance: a phenomics perspective. FUNCTIONAL PLANT BIOLOGY : FPB 2009; 36:880-892. [PMID: 32688699 DOI: 10.1071/fp09145] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 08/24/2009] [Indexed: 05/28/2023]
Abstract
Chlorophyll fluorescence imaging is a non-invasive, non-destructive means with which to examine the impact of fungal pathogens on the photosynthetic metabolism of host plants. As such, it has great potential for screening purposes in high-throughput phenomics environments. However, there is great diversity in the responses of plants to different plant-fungal pathogens and the choice of suitable experimental conditions and protocols and interpretation of the results requires both preliminary laboratory experiments and an understanding of the biology of the specific plant-pathogen interaction. In this review, we examine the interaction between biotrophic, hemi-biotrophic and necrotrophic fungal pathogens and their hosts to illustrate the extent to which chlorophyll fluorescence imaging can be used to detect the presence of disease before the appearance of visible symptoms, distinguish between compatible and incompatible fungal interactions, identify heterogeneity in photosynthetic performance within the infected leaf and provide insights into the underlying mechanisms. The limitations and challenges of using chlorophyll fluorescence imaging in high throughput screens is discussed.
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Affiliation(s)
- Julie D Scholes
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Stephen A Rolfe
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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68
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Vargas WA, Mandawe JC, Kenerley CM. Plant-derived sucrose is a key element in the symbiotic association between Trichoderma virens and maize plants. PLANT PHYSIOLOGY 2009; 151:792-808. [PMID: 19675155 PMCID: PMC2754623 DOI: 10.1104/pp.109.141291] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Accepted: 08/05/2009] [Indexed: 05/04/2023]
Abstract
Fungal species belonging to the genus Trichoderma colonize the rhizosphere of many plants, resulting in beneficial effects such as increased resistance to pathogens and greater yield and productivity. However, the molecular mechanisms that govern the recognition and association between Trichoderma and their hosts are still largely unknown. In this report, we demonstrate that plant-derived sucrose (Suc) is an important resource provided to Trichoderma cells and is also associated with the control of root colonization. We describe the identification and characterization of an intracellular invertase from Trichoderma virens (TvInv) important for the mechanisms that control the symbiotic association and fungal growth in the presence of Suc. Gene expression studies revealed that the hydrolysis of plant-derived Suc in T. virens is necessary for the up-regulation of Sm1, the Trichoderma-secreted elicitor that systemically activates the defense mechanisms in leaves. We determined that as a result of colonization of maize (Zea mays) roots by T. virens, photosynthetic rate increases in leaves and the functional expression of tvinv is crucial for such effect. In agreement, the steady-state levels of mRNA for Rubisco small subunit and the oxygen-evolving enhancer 3-1 were increased in leaves of plants colonized by wild-type T. virens. We conclude that during the symbiosis, the sucrolytic activity in the fungal cells affects the sink activity of roots, directing carbon partitioning toward roots and increasing the rate of photosynthesis in leaves. A discussion of the role of Suc in controlling the fungal proliferation on roots and its pivotal role in the coordination of plant-microbe associations is provided.
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Affiliation(s)
- Walter A Vargas
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas 77843, USA
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69
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Zanor MI, Osorio S, Nunes-Nesi A, Carrari F, Lohse M, Usadel B, Kühn C, Bleiss W, Giavalisco P, Willmitzer L, Sulpice R, Zhou YH, Fernie AR. RNA interference of LIN5 in tomato confirms its role in controlling Brix content, uncovers the influence of sugars on the levels of fruit hormones, and demonstrates the importance of sucrose cleavage for normal fruit development and fertility. PLANT PHYSIOLOGY 2009; 150:1204-18. [PMID: 19439574 PMCID: PMC2705052 DOI: 10.1104/pp.109.136598] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 05/09/2009] [Indexed: 05/18/2023]
Abstract
It has been previously demonstrated, utilizing intraspecific introgression lines, that Lycopersicum Invertase5 (LIN5), which encodes a cell wall invertase, controls total soluble solids content in tomato (Solanum lycopersicum). The physiological role of this protein, however, has not yet been directly studied, since evaluation of data obtained from the introgression lines is complicated by the fact that they additionally harbor many other wild species alleles. To allow a more precise comparison, we generated transgenic tomato in which we silenced the expression of LIN5 using the RNA interference approach. The transformants were characterized by an altered flower and fruit morphology, displaying increased numbers of petals and sepals per flower, an increased rate of fruit abortion, and a reduction in fruit size. Evaluation of the mature fruit revealed that the transformants were characterized by a reduction of seed number per plant. Furthermore, detailed physiological analysis revealed that the transformants displayed aberrant pollen morphology and a reduction in the rate of pollen tube elongation. Metabolite profiling of ovaries and green and red fruit revealed that metabolic changes in the transformants were largely confined to sugar metabolism, whereas transcript and hormone profiling revealed broad changes both in the hormones themselves and in transcripts encoding their biosynthetic enzymes and response elements. These results are discussed in the context of current understanding of the role of sugar during the development of tomato fruit, with particular focus given to its impact on hormone levels and organ morphology.
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Affiliation(s)
- María Inés Zanor
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany
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70
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Bolton MD. Primary Metabolism and Plant Defense—Fuel for the Fire. MOLECULAR PLANT-MICROBE INTERACTIONS® 2009; 22:487-97. [PMID: 19348567 DOI: 10.1094/mpmi-22-5-0487] [Citation(s) in RCA: 459] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plants have the ability to recognize and respond to a multitude of microorganisms. Recognition of pathogens results in a massive reprogramming of the plant cell to activate and deploy defense responses to halt pathogen growth. Such responses are associated with increased demands for energy, reducing equivalents, and carbon skeletons that are provided by primary metabolic pathways. Although pathogen recognition and downstream resistance responses have been the focus of major study, an intriguing and comparatively understudied phenomenon is how plants are able to recruit energy for the defense response. To that end, this review will summarize current research on energy-producing primary metabolism pathways and their role in fueling the resistance response.
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71
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Depuydt S, Trenkamp S, Fernie AR, Elftieh S, Renou JP, Vuylsteke M, Holsters M, Vereecke D. An integrated genomics approach to define niche establishment by Rhodococcus fascians. PLANT PHYSIOLOGY 2009; 149:1366-86. [PMID: 19118125 PMCID: PMC2649413 DOI: 10.1104/pp.108.131805] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 12/25/2008] [Indexed: 05/18/2023]
Abstract
Rhodococcus fascians is a Gram-positive phytopathogen that induces shooty hyperplasia on its hosts through the secretion of cytokinins. Global transcriptomics using microarrays combined with profiling of primary metabolites on infected Arabidopsis (Arabidopsis thaliana) plants revealed that this actinomycete modulated pathways to convert its host into a niche. The transcript data demonstrated that R. fascians leaves a very characteristic mark on Arabidopsis with a pronounced cytokinin response illustrated by the activation of cytokinin perception, signal transduction, and homeostasis. The microarray data further suggested active suppression of an oxidative burst during the R. fascians pathology, and comparison with publicly available transcript data sets implied a central role for auxin in the prevention of plant defense activation. Gene Ontology categorization of the differentially expressed genes hinted at a significant impact of infection on the primary metabolism of the host, which was confirmed by subsequent metabolite profiling. The much higher levels of sugars and amino acids in infected plants are presumably accessed by the bacteria as carbon and nitrogen sources to support epiphytic and endophytic colonization. Hexoses, accumulating from a significantly increased invertase activity, possibly inhibited the expression of photosynthesis genes and photosynthetic activity in infected leaves. Altogether, these changes are indicative of sink development in symptomatic tissues. The metabolomics data furthermore point to the possible occurrence of secondary signaling during the interaction, which might contribute to symptom development. These data are placed in the context of regulation of bacterial virulence gene expression, suppression of defense, infection phenotype, and niche establishment.
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Affiliation(s)
- Stephen Depuydt
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, 9052 Ghent, Belgium
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72
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Cho JI, Ryoo N, Eom JS, Lee DW, Kim HB, Jeong SW, Lee YH, Kwon YK, Cho MH, Bhoo SH, Hahn TR, Park YI, Hwang I, Sheen J, Jeon JS. Role of the rice hexokinases OsHXK5 and OsHXK6 as glucose sensors. PLANT PHYSIOLOGY 2009; 149:745-59. [PMID: 19010999 PMCID: PMC2633841 DOI: 10.1104/pp.108.131227] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 11/10/2008] [Indexed: 05/17/2023]
Abstract
The Arabidopsis (Arabidopsis thaliana) hexokinase 1 (AtHXK1) is recognized as an important glucose (Glc) sensor. However, the function of hexokinases as Glc sensors has not been clearly demonstrated in other plant species, including rice (Oryza sativa). To investigate the functions of rice hexokinase isoforms, we characterized OsHXK5 and OsHXK6, which are evolutionarily related to AtHXK1. Transient expression analyses using GFP fusion constructs revealed that OsHXK5 and OsHXK6 are associated with mitochondria. Interestingly, the OsHXK5DeltamTP-GFP and OsHXK6DeltamTP-GFP fusion proteins, which lack N-terminal mitochondrial targeting peptides, were present mainly in the nucleus with a small amount of the proteins seen in the cytosol. In addition, the OsHXK5NLS-GFP and OsHXK6NLS-GFP fusion proteins harboring nuclear localization signals were targeted predominantly in the nucleus, suggesting that these OsHXKs retain a dual-targeting ability to mitochondria and nuclei. In transient expression assays using promoterluciferase fusion constructs, these two OsHXKs and their catalytically inactive alleles dramatically enhanced the Glc-dependent repression of the maize (Zea mays) Rubisco small subunit (RbcS) and rice alpha-amylase genes in mesophyll protoplasts of maize and rice. Notably, the expression of OsHXK5, OsHXK6, or their mutant alleles complemented the Arabidopsis glucose insensitive2-1 mutant, thereby resulting in wild-type characteristics in seedling development, Glc-dependent gene expression, and plant growth. Furthermore, transgenic rice plants overexpressing OsHXK5 or OsHXK6 exhibited hypersensitive plant growth retardation and enhanced repression of the photosynthetic gene RbcS in response to Glc treatment. These results provide evidence that rice OsHXK5 and OsHXK6 can function as Glc sensors.
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Affiliation(s)
- Jung-Il Cho
- Plant Metabolism Research Center and Graduate School of Biotechnology, Department of Horticultural Biotechnology, Kyung Hee University, Yongin 446-701, Korea
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73
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Kocal N, Sonnewald U, Sonnewald S. Cell wall-bound invertase limits sucrose export and is involved in symptom development and inhibition of photosynthesis during compatible interaction between tomato and Xanthomonas campestris pv vesicatoria. PLANT PHYSIOLOGY 2008; 148:1523-36. [PMID: 18784281 PMCID: PMC2577280 DOI: 10.1104/pp.108.127977] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Accepted: 09/05/2008] [Indexed: 05/18/2023]
Abstract
Cell wall-bound invertase (cw-Inv) plays an important role in carbohydrate partitioning and regulation of sink-source interaction. There is increasing evidence that pathogens interfere with sink-source interaction, and induction of cw-Inv activity has frequently been shown in response to pathogen infection. To investigate the role of cw-Inv, transgenic tomato (Solanum lycopersicum) plants silenced for the major leaf cw-Inv isoforms were generated and analyzed during normal growth and during the compatible interaction with Xanthomonas campestris pv vesicatoria. Under normal growth conditions, activities of sucrolytic enzymes as well as photosynthesis and respiration were unaltered in the transgenic plants compared with wild-type plants. However, starch levels of source leaves were strongly reduced, which was most likely caused by an enhanced sucrose exudation rate. Following X. campestris pv vesicatoria infection, cw-Inv-silenced plants showed an increased sucrose to hexose ratio in the apoplast of leaves. Symptom development, inhibition of photosynthesis, and expression of photosynthetic genes were clearly delayed in transgenic plants compared with wild-type plants. In addition, induction of senescence-associated and pathogenesis-related genes observed in infected wild-type plants was abolished in cw-Inv-silenced tomato lines. These changes were not associated with decreased bacterial growth. In conclusion, cw-Inv restricts carbon export from source leaves and regulates the sucrose to hexose ratio in the apoplast. Furthermore, an increased apoplastic hexose to sucrose ratio can be linked to inhibition of photosynthesis and induction of pathogenesis-related gene expression but does not significantly influence bacterial growth. Indirectly, bacteria may benefit from low invertase activity, since the longevity of host cells is raised and basal defense might be dampened.
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Affiliation(s)
- Nurcan Kocal
- Friedrich-Alexander Universität Erlangen-Nürnberg, Lehrstuhl für Biochemie, 91058 Erlangen, Germany
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74
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Riewe D, Grosman L, Zauber H, Wucke C, Fernie AR, Geigenberger P. Metabolic and developmental adaptations of growing potato tubers in response to specific manipulations of the adenylate energy status. PLANT PHYSIOLOGY 2008; 146:1579-98. [PMID: 18305207 PMCID: PMC2287335 DOI: 10.1104/pp.108.115758] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 02/21/2008] [Indexed: 05/20/2023]
Abstract
Heterotrophic carbon metabolism has been demonstrated to be limited by oxygen availability in a variety of plant tissues, which in turn inevitably affects the adenylate status. To study the effect of altering adenylate energy metabolism, without changing the oxygen supply, we expressed a plastidially targeted ATP/ADP hydrolyzing phosphatase (apyrase) in tubers of growing potato (Solanum tuberosum) plants under the control of either inducible or constitutive promoters. Inducible apyrase expression in potato tubers, for a period of 24 h, resulted in a decrease in the ATP-content and the ATP-ADP ratio in the tubers. As revealed by metabolic profiling, this was accompanied by a decrease in the intermediates of sucrose to starch conversion and several plastidially synthesized amino acids, indicating a general depression of tuber metabolism. Constitutive tuber-specific apyrase expression did not lead to a reduction of ATP, but rather a decrease in ADP and an increase in AMP levels. Starch accumulation was strongly inhibited and shifted to the production of amylopectin instead of amylose in these tubers. Furthermore, the levels of almost all amino acids were decreased, although soluble sugars and hexose-Ps were highly abundant. Respiration was elevated in the constitutively expressing lines indicating a compensation for the dramatic increase in ATP hydrolysis. The increase in respiration did not affect the internal oxygen tensions in the tubers. However, the tubers developed a ginger-like phenotype having an elevated surface-volume ratio and a reduced mass per tuber. Decreased posttranslational redox activation of ADP-glucose pyrophosphorylase and a shift in the ratio of soluble starch synthase activity to granule-bound starch synthase activity were found to be partially responsible for the alterations in starch structure and abundance. The activity of alcohol dehydrogenase was decreased and pyruvate decarboxylase was induced, but this was neither reflected by an increase in fermentation products nor in the cellular redox state, indicating that fermentation was not yet induced in the transgenic lines. When taken together the combined results of these studies allow the identification of both short- and long-term adaptation of plant metabolism and development to direct changes in the adenylate status.
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Affiliation(s)
- David Riewe
- Max-Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
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75
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Horst RJ, Engelsdorf T, Sonnewald U, Voll LM. Infection of maize leaves with Ustilago maydis prevents establishment of C4 photosynthesis. JOURNAL OF PLANT PHYSIOLOGY 2008; 165:19-28. [PMID: 17689830 DOI: 10.1016/j.jplph.2007.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 05/15/2007] [Accepted: 05/16/2007] [Indexed: 05/08/2023]
Abstract
The Basidiomycete fungus Ustilago maydis is the common agent of corn smut and is capable of inducing gall growth on infected tissue of the C4 plant maize (Zea mays). While U. maydis is very well characterized on the genetic level, the physiological changes in the host plant in response to U. maydis infection have not been studied in detail, yet. Therefore, we examined the influence of U. maydis infection on photosynthetic performance and carbon metabolism in maize leaf galls. At all stages of development, U. maydis-induced leaf galls exhibited carbon dioxide response curves, CO2 compensation points and enzymatic activities that are characteristic of C3 photosynthesis, demonstrating that the establishment of C4 metabolism is prevented in infected tissue. Hexose contents and hexose/sucrose ratio of leaf galls remained high at 6 days post infection, while a shift in free sugar metabolism was observed in the uninfected controls at that time point. Concomitantly, transitory starch production and sucrose accumulation during the light period remained low in leaf galls. Given that U. maydis is infectious on young developing tissue, the observed changes in carbohydrate metabolism suggest that the pathogen manipulates the developing leaf tissue to arrest sink-to-source transition in favor of maintaining sink metabolism in the host cells. Furthermore, evidence is presented that carbohydrate supply during the biotrophic phase of the pathogen is assured by a fungal invertase.
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Affiliation(s)
- Robin J Horst
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Lehrstuhl für Biochemie, Staudtstr. 5, D-91058 Erlangen, Germany
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76
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Dardick C. Comparative expression profiling of Nicotiana benthamiana leaves systemically infected with three fruit tree viruses. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:1004-17. [PMID: 17722703 DOI: 10.1094/mpmi-20-8-1004] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Plant viruses cause a wide array of disease symptoms and cytopathic effects. Although some of these changes are virus specific, many appear to be common even among diverse viruses. Currently, little is known about the underlying molecular determinants. To identify gene expression changes that are concomitant with virus symptoms, we performed comparative expression profiling experiments on Nicotiana benthamiana leaves infected with one of three different fruit tree viruses that produce distinct symptoms: Plum pox potyvirus (PPV; leaf distortion and mosaic), Tomato ringspot nepovirus (ToRSV; tissue necrosis and general chlorosis), and Prunus necrotic ringspot ilarvirus (PNRSV; subtle chlorotic mottling). The numbers of statistically significant genes identified were consistent with the severity of the observed symptoms: 1,082 (ToRSV), 744 (PPV), and 89 (PNRSV). In all, 56% of the gene expression changes found in PPV-infected leaves also were altered by ToRSV, 87% of which changed in the same direction. Both PPV- and ToRSV-infected leaves showed widespread repression of genes associated with plastid functions. PPV uniquely induced the expression of large numbers of cytosolic ribosomal genes whereas ToRSV repressed the expression of plastidic ribosomal genes. How these and other observed expression changes might be associated with symptom development are discussed.
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Affiliation(s)
- Christopher Dardick
- United States Department of Agriculture-Agricultural Research Service, Appalachian Fruit Research Station, Kearneysville, WV, USA.
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77
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Lytovchenko A, Sonnewald U, Fernie AR. The complex network of non-cellulosic carbohydrate metabolism. CURRENT OPINION IN PLANT BIOLOGY 2007; 10:227-35. [PMID: 17434793 DOI: 10.1016/j.pbi.2007.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 04/02/2007] [Indexed: 05/04/2023]
Abstract
Partitioning of carbon dominates intracellular fluxes in both photosynthetic and heterotrophic plant tissues, and has vast influence on both plant growth and development. Recently, much progress has been made in elucidating the structures of the biosynthetic and degradative pathways that link the major and minor pools of soluble carbohydrates to cellular polymers such as starch, heteroglycans and fructans. In most cases, the regulatory properties of these pathways have been elucidated and the enzymes involved have been investigated using reverse genetics approaches. Although many of the results from these approaches were merely confirmatory, several of them were highly unexpected. The challenge ahead is to achieve better understanding of metabolic regulation at the network level in order to develop more rational strategies for metabolic engineering.
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Affiliation(s)
- Anna Lytovchenko
- Abteilung Willmitzer, Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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78
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Zhu J, Gopinath K, Murali A, Yi G, Hayward SD, Zhu H, Kao C. RNA-binding proteins that inhibit RNA virus infection. Proc Natl Acad Sci U S A 2007; 104:3129-34. [PMID: 17360619 PMCID: PMC1805585 DOI: 10.1073/pnas.0611617104] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Indexed: 12/30/2022] Open
Abstract
Arrays of >5,000 Saccharomyces cerevisiae proteins were screened to identify proteins that can preferentially bind a small RNA hairpin that contains a clamped adenine motif (CAM). A CAM is required for the replication of Brome Mosaic Virus (BMV), a plant-infecting RNA virus that can replicate in S. cerevisiae. Several hits were selected for further characterization in Nicotiana benthamiana. Pseudouridine Synthase 4 (Pus4) and the Actin Patch Protein 1 (App1) modestly reduced BMV genomic plus-strand RNA accumulation, but dramatically inhibited BMV systemic spread in plants. Pus4 also prevented the encapsidation of a BMV RNA in plants and the reassembly of BMV virions in vitro. These results demonstrate the feasibility of using proteome arrays to identify specific RNA-binding proteins for antiviral activities. Furthermore, the effects of Pus4 suggest that the CAM-containing RNA motif provides a regulatory link between RNA replication and encapsidation.
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Affiliation(s)
- Jian Zhu
- *Department of Pharmacology and Molecular Sciences and
- High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
| | - Kodetham Gopinath
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | - Ayaluru Murali
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | - Guanghui Yi
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | | | - Heng Zhu
- *Department of Pharmacology and Molecular Sciences and
- High Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, MD 21205; and
| | - Cheng Kao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
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Culver JN, Padmanabhan MS. Virus-induced disease: altering host physiology one interaction at a time. ANNUAL REVIEW OF PHYTOPATHOLOGY 2007; 45:221-43. [PMID: 17417941 DOI: 10.1146/annurev.phyto.45.062806.094422] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Virus infections are the cause of numerous plant disease syndromes that are generally characterized by the induction of disease symptoms such as developmental abnormalities, chlorosis, and necrosis. How viruses induce these disease symptoms represents a long-standing question in plant pathology. Recent studies indicate that symptoms are derived from specific interactions between virus and host components. Many of these interactions have been found to contribute to the successful completion of the virus life-cycle, although the role of other interactions in the infection process is not yet known. However, all share the potential to disrupt host physiology. From this information we are beginning to decipher the progression of events that lead from specific virus-host interactions to the establishment of disease symptoms. This review highlights our progress in understanding the mechanisms through which virus-host interactions affect host physiology. The emerging picture is one of complexity involving the individual effects of multiple virus-host interactions.
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Affiliation(s)
- James N Culver
- Center for Biosystems Research, University of Maryland Biotechnology Institute, Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA.
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