Root Exudates From Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn. ex Sm. Seedlings and Their Effect on Phytophthora cinnamomi Rands

1977 ◽  
Vol 25 (5) ◽  
pp. 501 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Root Exudates ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Qualitative Difference ◽  
Mycelium Growth ◽  
Eucalyptus Marginata ◽  
Chlamydospore Germination ◽  
Sampling Times

Root exudates from seedling eucalypts were collected aseptically, analysed for sugars, amino acids and organic acids and an examination made of their effect on zoospore chemotaxis, mycelium growth and chlamydospore germination of Phytophthora cinnamomi. Seedlings of root-rot susceptible Eucalyptus marginata produced greater concentrations of sugar and amino acid exudates than the root-rot resistant Eucalyptus calophylla at all sampling times. There was, however, little qualitative difference between the eucalypt root exudates. Both eucalypts attracted zoospores to roots in culture tubes. Infection of the roots followed encystment and germination of the zoospores. Germination of chlamydospores and mycelium growth of P.cinnamomi was significantly increased by the presence of root exudates and no differences were observed between exudates of the two species. Only amino acids and organic acids stimulated germination of chlamydospores. It was concluded that differences in root-rot susceptibility of eucalypts to P.cinnamomi are not attributable to differences in root exudate from eucalypt seedlings.

Activation of soil enzymes by addition of artificial root exudate combinations

2020 ◽  
Author(s):  
Diane Hagmann ◽  
Jennifer Krumins ◽  
Bhagyashree Vaidya ◽  
Nina Goodey
Keyword(s):  
Amino Acids ◽  
Microbial Community ◽  
Organic Acids ◽  
Enzymatic Activity ◽  
Root Exudates ◽  
Soil Microbial Community ◽  
Soil Function ◽  
Soil Enzymatic Activity ◽  
Soil Microbial ◽  
Barren Soil

<p>In vegetated soils,plants naturally release root exudates, consisting of sugars, organic acids, and amino acids, into the soil increasing soil enzymatic activity.  Liberty State Park, located in Jersey City, New Jersey, is an industrial brownfield contaminated with heavy metals and organic pollutants.  Some sites have soils that function poorly, as indicated by low soil enzymatic activity, and do not support plant growth.  This study will determine whether different combinations of artificial root exudates increase soil enzymatic activity in these contaminated and low functioning soils. Different combinations of sugars, organic acids, and amino acids and will be added to barren, poorly functioning soil.  Three soil enzymatic activities will be examined at several time points over 120 days to assess the impacts of different combinations of root exudates on soil function. Further, soil microbial community composition will be determined to examine whether different artificial exudate solutions result in changes in soil microbial community.  Preliminary results suggest that the combination of sugars, organic acids, and amino acids greatly increased phosphatase, cellobiohydrolase, and L-leucine amino peptidase activity over time in poorly-functioning, barren soil from Liberty State Park. The other combinations (sugars and organic acids, sugars and amino acids, organic acids and amino acids) also increase the three enzyme activities more than the individual groups. Dormant microbes in barren soil can possibly be revived with the addition of artificial root exudates to mimic the presence of plants in revitalizing the microbial communities and improving soil function. </p>

scholarly journals Methods of plant root exudates analysis: a review

2011 ◽  
Vol 59 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Peter Dundek ◽  
Ladislav Holík ◽  
Tomáš Rohlík ◽  
Ladislav Hromádko ◽  
Valerie Vranová ◽  
...  
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Root Exudates ◽  
Organic Molecules ◽  
Current Knowledge ◽  
Plant Root ◽  
Water Soluble ◽  
Low Molecular Weight ◽  
Total Carbohydrates ◽  
Electrophoresis Of Proteins

The aim of this review is to summarise current knowledge on methods being used to determine individual compounds and properties of water-soluble plant root exudates. These compounds include amino acids, organic acids and simple sugars, as well as polysaccharides, proteins and organic substances. Qualitative composition of water-soluble root exudates and exudation rate are commonly measured with the aim of consequent synthetic preparation of plant root exudates to be supplied to soil to create artificial rhizosphere for different experimental purposes. Root exudates collection usually requires consequent filtration or centrifugation to remove solids, root detritus and microbial cell debris, and consequent concentration using an evaporator, lyophilizator or ultrafiltration. Methods used for analysis of total groups of compounds (total proteins and total carbohydrates) and total organic carbon are simple. On the other hand, HPLC or GS/MS are commonly used to analyse individual low molecular weight organic molecules (sugars, organic acids and amino acids) with separation using different columns. Other properties such as pH, conductivity or activity of different enzymes as well as gel electrophoresis of proteins are sometimes assessed. All of these methods are discussed in this work.

scholarly journals Identification of Chemotaxis Compounds in Root Exudates and Their Sensing Chemoreceptors in Plant-Growth-Promoting Rhizobacteria Bacillus amyloliquefaciens SQR9

2018 ◽  
Vol 31 (10) ◽  
pp. 995-1005 ◽  
Author(s):  
Haichao Feng ◽  
Nan Zhang ◽  
Wenbin Du ◽  
Huihui Zhang ◽  
Yunpeng Liu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Plant Growth ◽  
Organic Acids ◽  
Root Exudates ◽  
Bacillus Amyloliquefaciens ◽  
Plant Growth Promoting Rhizobacteria ◽  
Titration Calorimetry ◽  
Chemotaxis Proteins ◽  
Plant Growth Promoting ◽  
Growth Promoting

Chemotaxis-mediated response to root exudates, initiated by sensing-specific ligands through methyl-accepting chemotaxis proteins (MCP), is very important for root colonization and beneficial functions of plant-growth-promoting rhizobacteria (PGPR). Systematic identification of chemoattractants in complex root exudates and their sensing chemoreceptors in PGPR is helpful for enhancing their recruitment and colonization. In this study, 39 chemoattractants and 5 chemorepellents, including amino acids, organic acids, and sugars, were identified from 98 tested components of root exudates for the well-studied PGPR strain Bacillus amyloliquefaciens SQR9. Interestingly, mutant stain SQR9Δ8mcp, with all eight putative chemoreceptors completely deleted, lost the chemotactic responses to those 44 compounds. Gene complementation, chemotaxis assay, and isothermal titration calorimetry analysis revealed that McpA was mainly responsible for sensing organic acids and amino acids, while McpC was mostly for amino acids. These two chemoreceptors may play important roles in the rhizosphere chemotaxis of SQR9. In contrast, the B. amyloliquefaciens-unique chemoreceptor McpR was specifically responsible for arginine, and residues Tyr-78, Thr-131, and Asp-162 were critical for arginine binding. This study not only deepened our insights into PGPR–root interaction but also provided useful information to enhance the rhizosphere chemotaxis mobility and colonization of PGPR, which will promote their application in agricultural production.

scholarly journals Dominant amino acids, organic acids and sugars in water-soluble root exudates of C4 plants: a mini-review

2010 ◽  
Vol 58 (5) ◽  
pp. 441-446 ◽  
Author(s):  
Valerie Vranová ◽  
Hana Kaňová ◽  
Klement Rejšek ◽  
Pavel Formánek
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Aspartic Acid ◽  
Root Exudates ◽  
Water Soluble ◽  
C4 Plants ◽  
Aminobutyric Acid ◽  
Organic Acids And Sugars

The aim of this mini-review was to identify the dominant carbohydrates, organic acids and amino ­acids in water-soluble root exudates of plants which represent dominant compounds there. The study is focused on plants of C4-type of metabolism taking into account available literature. From group of carbohydrates, those dominant are represented glucose, fructose, arabinose and sucrose. Between dominant amino acids occurring in root exudates of C4-metabolism plants are alanine, se­rine, arginine, glutamine, glutamic and aspartic acid, glycine, proline, cystine, lysine and g-aminobutyric acid. Citric, malic, tartaric, succinic, trans-aconitic represent the dominant organic acids. This knowledge may be useful for planning analyses of these compounds in root exudates of C4plants. Except for this preparation of synthetic root exudates to simulate rhizosphere of C4plants may be performed based on these results.

Infection by Phytophthora cinnamomi Rands of Roots of Eucalyptus calophylla R.Br. and Eucalyptus marginata Donn. ex Sm

1977 ◽  
Vol 25 (5) ◽  
pp. 483 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb ◽  
CA Parker
Keyword(s):  
Phytophthora Cinnamomi ◽  
Light And Electron Microscopy ◽  
Inhibitory Effect ◽  
Lateritic Soil ◽  
Root Damage ◽  
Mature Trees ◽  
Cortical Cells ◽  
Eucalyptus Marginata ◽  
Seedling Roots ◽  
Loam Soil

On lateritic podzolic soils in Western Australia Eucalyptus calophylla is resistant to Phytophthora cinnamomi whereas Eucalyptus marginata is susceptible and eventually killed by the pathogen. On loam soils both eucalypts are resistant. Possible mechanisms for resistance of E. calophylla in lateritic soil and the inhibitory action of loam soils were investigated. Aseptically raised eucalypt seedlings succumbed to infection in liquid culture tubes. The mechanism of infection was compared by light and electron microscopy which showed similar fungal invasion and penetration into roots of both eucalypt species. Vegetative hyphae initially penetrated intercellularly and proliferated rapidly within cortical and stelar tissue. Intracellular invasion of these tissues occurred 48hr after initial infection through dissolution of the host cell wall. Chlamydospores were formed within a number of cortical cells. Unsuberized roots of mature trees produced aseptically showed reactions to invasion similar to those of the eucalypt seedling roots. Suberized roots were not invaded. The addition of small quantities of lateritic soil to sterile sand so as to introduce soil micro-organisms without altering the chemical and physical status of the sand, and subsequent inoculation of the sand with P.cinnamomi, resulted in a reduction of root damage on both eucalypts when compared with seedlings raised in sterile sand. Roots of E.calophylla were less severely damaged than those of E.marginata. The addition of small quantities of loam soil significantly reduced root damage in seedlings of both species. These results parallel both pot experiments and field observations, and suggest that microorganisms of the rhizosphere may be an important factor in the resistance of E.calophylla to infection, and in the inhibitory effect of loam soil on P.cinnamomi.

scholarly journals Cellulase Activity as a Mechanism for Suppression of Phytophthora Root Rot in Mulches

2011 ◽  
Vol 101 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Brantlee Spakes Richter ◽  
Kelly Ivors ◽  
Wei Shi ◽  
D. M. Benson
Keyword(s):  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Cellulase Activity ◽  
Enzyme Concentration ◽  
Disease Suppression ◽  
In Vitro Assays ◽  
Infested Soil ◽  
Phytophthora Root Rot ◽  
Standard Curve

Wood-based mulches are used in avocado production and are being tested on Fraser fir for reduction of Phytophthora root rot, caused by Phytophthora cinnamomi. Research with avocado has suggested a role of microbial cellulase enzymes in pathogen suppression through effects on the cellulosic cell walls of Phytophthora. This work was conducted to determine whether cellulase activity could account for disease suppression in mulch systems. A standard curve was developed to correlate cellulase activity in mulches with concentrations of a cellulase product. Based on this curve, cellulase activity in mulch samples was equivalent to a cellulase enzyme concentration of 25 U ml–1 or greater of product. Sustained exposure of P. cinnamomi to cellulase at 10 to 50 U ml–1 significantly reduced sporangia production, but biomass was only reduced with concentrations over 100 U ml–1. In a lupine bioassay, cellulase was applied to infested soil at 100 or 1,000 U ml–1 with three timings. Cellulase activity diminished by 47% between 1 and 15 days after application. Cellulase applied at 100 U ml–1 2 weeks before planting yielded activity of 20.08 μmol glucose equivalents per gram of soil water (GE g–1 aq) at planting, a level equivalent to mulch samples. Cellulase activity at planting ranged from 3.35 to 48.67 μmol GE g–1 aq, but no treatment significantly affected disease progress. Based on in vitro assays, cellulase activity in mulch was sufficient to impair sporangia production of P. cinnamomi, but not always sufficient to impact vegetative biomass.

scholarly journals Profiles of Secondary Metabolites (Phenolic Acids, Carotenoids, Anthocyanins, and Galantamine) and Primary Metabolites (Carbohydrates, Amino Acids, and Organic Acids) during Flower Development in Lycoris radiata

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 248
Author(s):  
Chang Ha Park ◽  
Hyeon Ji Yeo ◽  
Ye Jin Kim ◽  
Bao Van Nguyen ◽  
Ye Eun Park ◽  
...  
Keyword(s):  
Amino Acids ◽  
Secondary Metabolites ◽  
Organic Acids ◽  
Phenolic Acids ◽  
Flower Development ◽  
Developmental Stages ◽  
Tca Cycle ◽  
Primary And Secondary Metabolites ◽  
Hydrophilic Compounds ◽  
Tca Cycle Intermediates

This study aimed to elucidate the variations in primary and secondary metabolites during Lycorisradiata flower development using high performance liquid chromatography (HPLC) and gas chromatography time-of-flight mass spectrometry (GC-TOFMS). The result showed that seven carotenoids, seven phenolic acids, three anthocyanins, and galantamine were identified in the L. radiata flowers. Most secondary metabolite levels gradually decreased according to the flower developmental stages. A total of 51 metabolites, including amines, sugars, sugar intermediates, sugar alcohols, amino acids, organic acids, phenolic acids, and tricarboxylic acid (TCA) cycle intermediates, were identified and quantified using GC-TOFMS. Among the hydrophilic compounds, most amino acids increased during flower development; in contrast, TCA cycle intermediates and sugars decreased. In particular, glutamine, asparagine, glutamic acid, and aspartic acid, which represent the main inter- and intracellular nitrogen carriers, were positively correlated with the other amino acids and were negatively correlated with the TCA cycle intermediates. Furthermore, quantitation data of the 51 hydrophilic compounds were subjected to partial least-squares discriminant analyses (PLS-DA) to assess significant differences in the metabolites of L. radiata flowers from stages 1 to 4. Therefore, this study will serve as the foundation for a biochemical approach to understand both primary and secondary metabolism in L. radiata flower development.

scholarly journals Phytophthora mediterranea sp. nov., a New Species Closely Related to Phytophthora cinnamomi from Nursery Plants of Myrtus communis in Italy

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 682
Author(s):  
Carlo Bregant ◽  
Antonio A. Mulas ◽  
Giovanni Rossetto ◽  
Antonio Deidda ◽  
Lucia Maddau ◽  
...  
Keyword(s):  
New Species ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Colony Growth ◽  
Phytophthora Species ◽  
Maximum Temperature ◽  
Pathogenicity Test ◽  
Forest Nurseries ◽  
Collar And Root Rot ◽  
A New Species

Monitoring surveys of Phytophthora related diseases in four forest nurseries in Italy revealed the occurrence of fourteen Phytophthora species to be associated with collar and root rot on fourteen plants typical of Mediterranean and alpine regions. In addition, a multilocus phylogeny analysis based on nuclear ITS and ß-tubulin and mitochondrial cox1 sequences, as well as micromorphological features, supported the description of a new species belonging to the phylogenetic clade 7c, Phytophthora mediterranea sp. nov. Phytophthora mediterranea was shown to be associated with collar and root rot symptoms on myrtle seedlings. Phylogenetically, P. mediterranea is closely related to P. cinnamomi but the two species differ in 87 nucleotides in the three studied DNA regions. Morphologically P. mediterranea can be easily distinguished from P. cinnamomi on the basis of its smaller sporangia, colony growth pattern and higher optimum and maximum temperature values. Data from the pathogenicity test showed that P. mediterranea has the potential to threaten the native Mediterranean maquis vegetation. Finally, the discovery of P. cinnamomi in alpine nurseries, confirms the progressive expansion of this species towards cold environments, probably driven by climate change.

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