TRANSPORT OF SUGAR IN <i>PHYTOPHTHORA PALMIVORA</i> (BUTL.) BUTL.

Sheard, J.; Farrar, J. F.

doi:10.1111/j.1469-8137.1987.tb00863.x

Cited by 9 publications

(3 citation statements)

References 18 publications

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“…Due to the finding that sucrose contents decreased and glucose and fructose concentrations increased simultaneously in infected and non‐infected roots of the split root experiment, we conclude that invertases might be involved locally and systemically in the conversion of sucrose into both hexoses during the growth of P. citricola in beech roots. In addition, Sheard and Farrar (1987) concluded from their data that sucrose is probably hydrolyzed extracellularly by invertases, before glucose is taken up by a high affinity hexose carrier of P. palmivora . Plants possess three types of invertase isoenzymes that are essential for supplying carbohydrates to sink organs as key enzymes for apoplastic phloem unloading (Roitsch and Gonzalez 2004).…”

Section: Discussionmentioning

confidence: 99%

Histological, physiological and molecular investigations of Fagus sylvatica seedlings infected with Phytophthora citricola

et al. 2010

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The aim of the work was to shed light into histological, physiological and molecular changes of Fagus sylvatica seedlings infected with the root pathogen Phytophthora citricola with the final goal to distinguish between local and systemic responses. Real-time quantitative PCR analysis proved that P. citricola was able to grow from infected roots into hypocotyl and epicotyl tissue of F. sylvatica seedlings. Light microscopy showed many collapsed parenchyma cells of the cortex without being penetrated by the pathogen. Hyphae were mainly growing intracellular in parenchyma and xylem tissue. Transmission electron microscopy displayed disintegration of xylem vessels and of parenchyma cells. Inhibition of water uptake of infected beech seedlings was positively correlated with the concentration of zoospores used in the experiment. In addition, a split root experiment indicated that invertases were possibly involved locally and systemically in the conversion of sucrose of P. citricola infected roots. During the growth of the pathogen in roots, a transient expression of the 1-aminocyclopropane-1-carboxylic acid (ACC)-oxidase gene was quantified in leaves which was detected in parallel with the first peak of a biphasic ethylene outburst. Additionally a systemic upregulation of aquaporin transcripts was mainly detected in leaves of beech seedlings infected with P. citricola.

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Section: Discussionmentioning

confidence: 99%

Histological, physiological and molecular investigations of Fagus sylvatica seedlings infected with Phytophthora citricola

et al. 2010

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“…Although reduced sucrose may have been sufficient to down‐regulate the invertases, this is unlikely to have been perceived as a diminution in available carbon as fructose and glucose rose concomitantly. In addition, the hexoses are probably the primary sugar source for Phytophthora as its cell wall‐bound invertase activity substantially exceeds the maximum uptake rate of sucrose through transmembrane carriers (Sheard and Farrar, 1987).…”

Section: Discussionmentioning

confidence: 99%

Metabolic adaptation of Phytophthora infestans during growth on leaves, tubers and artificial media

Judelson¹,

Tani²,

Narayan³

2009

Molecular Plant Pathology

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SUMMARYEfficient 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.m pp_570 843..856

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“…By converting carbon dioxide and water to bicarbonate and protons, carbonic anhydrases are candidate effectors that may acidify the haustorial interface to benefit the pathogen. It is interesting that the invertase of Phytophthora palmivora was shown to function optimally at a slightly acidic pH ( 35 ). Our analysis may underestimate the number of secreted enzyme activities that, like carbonic anhydrases, are coexpressed with invertases.…”

Section: Discussionmentioning

confidence: 99%

Invertases in Phytophthora infestans Localize to Haustoria and Are Programmed for Infection-Specific Expression

Kagda

Martínez‐Soto

Ah‐Fong

et al. 2020

mBio

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The oomycete Phytophthora infestans, the causal agent of potato and tomato blight, expresses two extracellular invertases. Unlike typical fungal invertases, the P. infestans genes are not sucrose induced or glucose repressed but instead appear to be under developmental control. Transcript levels of both genes were very low in mycelia harvested from artificial medium but high in preinfection stages (sporangia, zoospores, and germinated cysts), high during biotrophic growth in leaves and tubers, and low during necrotrophy. Genome-wide analyses of metabolic enzymes and effectors indicated that this expression profile was fairly unusual, matched only by a few other enzymes, such as carbonic anhydrases and a few RXLR effectors. Genes for other metabolic enzymes were typically downregulated in the preinfection stages. Overall metabolic gene expression during the necrotrophic stage of infection clustered with artificial medium, while the biotrophic phase formed a separate cluster. Confocal microscopy of transformants expressing green fluorescent protein (GFP) fusions indicated that invertase protein resided primarily in haustoria during infection. This localization was not attributable to haustorium-specific promoter activity. Instead, the N-terminal regions of proteins containing signal peptides were sufficient to deliver proteins to haustoria. Invertase expression during leaf infection was linked to a decline in apoplastic sucrose, consistent with a role of the enzymes in plant pathogenesis. This was also suggested by the discovery that invertase genes occur across multiple orders of oomycetes but not in most animal pathogens or a mycoparasite. IMPORTANCE Oomycetes cause hundreds of diseases in economically and environmentally significant plants. How these microbes acquire host nutrients is not well understood. Many oomycetes insert specialized hyphae called haustoria into plant cells, but unlike their fungal counterparts, a role in nutrition has remained unproven. The discovery that Phytophthora invertases localize to haustoria provides the first strong evidence that these structures participate in feeding. Since regions of proteins containing signal peptides targeted proteins to the haustorium-plant interface, haustoria appear to be the primary machinery for secreting proteins during biotrophic pathogenesis. Although oomycete invertases were acquired laterally from fungi, their expression patterns have adapted to the Phytophthora lifestyle by abandoning substrate-level regulation in favor of developmental control, allowing the enzymes to be produced in anticipation of plant colonization. This study highlights how a widely distributed hydrolytic enzyme has evolved new behaviors in oomycetes.

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TRANSPORT OF SUGAR IN PHYTOPHTHORA PALMIVORA (BUTL.) BUTL.

Cited by 9 publications

References 18 publications

Histological, physiological and molecular investigations of Fagus sylvatica seedlings infected with Phytophthora citricola

Histological, physiological and molecular investigations of Fagus sylvatica seedlings infected with Phytophthora citricola

Metabolic adaptation of Phytophthora infestans during growth on leaves, tubers and artificial media

Invertases in Phytophthora infestans Localize to Haustoria and Are Programmed for Infection-Specific Expression

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