Evidence against involvement of pectic enzymes in the invasion of root hairs by Rhizobium trifolii

1969 ◽  
Vol 15 (6) ◽  
pp. 643-645 ◽  
Author(s):  
James D. Macmillan ◽  
Roderic C. Cooke
Keyword(s):  
Root Hairs ◽  
Red Clover ◽  
Infection Process ◽  
Pectin Lyase ◽  
Rhizobium Trifolii ◽  
Leguminous Plants ◽  
Pectic Enzymes ◽  
Lyase Activity ◽  
Rhizobium Spp ◽  
Polygalacturonate Lyase

It has been postulated that polygalacturonase is significant in the infection of root hairs of leguminous plants by Rhizobium spp. Recently this theory has been strongly questioned. Evidence for polygalacturonase was based on methods which would not distinguish between this enzyme and other pectic glycosidases. The possibility that pectin lyase or polygalacturonate lyase is involved in the invasion of red clover by Rhizobium trifolii was investigated. Weak pectin lyase activity was detected in uninoculated seedlings, but no increase in the activity was produced in inoculated seedlings. It was concluded that neither of the lyases has significance in the infection process.

scholarly journals Effect of Fusicoccin on the Early Infection Process of Legume Roots by Rhizobium spp

1999 ◽  
Vol 12 (12) ◽  
pp. 1090-1094 ◽  
Author(s):  
Juan Pedro Donaire ◽  
María Pilar Rodríguez-Rosales ◽  
María José Soto ◽  
Juan Sanjuan ◽  
José Olivares
Keyword(s):  
Plasma Membrane ◽  
Root Hairs ◽  
Infection Process ◽  
Calcium Signal ◽  
Ionophore A23187 ◽  
Cytosolic Ph ◽  
Membrane Hyperpolarization ◽  
Nod Factor ◽  
Rhizobium Spp ◽  
External Calcium

Nod factors, the first detectable signals produced by Rhizobium spp., were reported to induce cytosolic pH changes and plasma membrane depolarization in root hairs as specific responses. In this study, it has been found that fusicoccin inhibits nodulation of alfalfa roots. This inhibition was only observed when fusicoccin was applied in the earlier steps of the bacteria-plant interaction. The observed effect is similar to that caused by the undissociated permeant acetic acid, which decreases the cytoplasmic pH and, like fusicoccin, significantly stimulates net H+ efflux. These results suggest that the fusicoccin-induced plasma membrane H+-ATPase activity and membrane hyperpolarization could be responsible for the nodulation inhibition observed. Moreover, it was found that nodulation was inhibited by removing external calcium with EGTA. When fusicoccin is present, a lower concentration of EGTA is necessary to inhibit nodulation. Furthermore, the addition of Ca2+ ionophore A23187 was found to inhibit H+ efflux by roots. These observations support the idea that the Nod factor-triggered calcium signal modulates the activity of the proton pump.

Multiple forms of pectic lyases and polygalacturonase from Fusarium oxysporum f,.sp. radicis lycopersici: regulation of their synthesis by galacturonic acid

1997 ◽  
Vol 43 (3) ◽  
pp. 245-253 ◽  
Author(s):  
M. A. Guevara ◽  
P. Estévez ◽  
M. T. González-Jaén
Keyword(s):  
Fusarium Oxysporum ◽  
Galacturonic Acid ◽  
Pectate Lyase ◽  
Pectin Lyase ◽  
Multiple Forms ◽  
Pectic Enzymes ◽  
Weak Preference ◽  
Absolute Requirement ◽  
Lyase Activity ◽  
Polygalacturonase Activity

The r2 isolate of Fusarium oxysporum f.sp. radicis-lycopersici produced several pectic enzymes that differ in substrate preference, reaction mechanism, and action pattern. We detected three forms that have lyase activity, four forms with polygalacturonase activity and one form with pectinesterase activity. Lyases had an absolute requirement for calcium and pIs of 9.20, 9.00, and 8.65. The two more alkaline forms had a weak preference for pectin, whereas the other was more active on polygalacturonate. Polygalacturonases had pIs of 9.30, 7.35, 6.85, and 6.55 and were inhibited by calcium ions. Lyases and polygalacturonases were induced by galacturonic acid and were subject to catabolite repression. Induced synthesis occurred at pHs 5.5 and 8.0 and no increase in lyase activities were promoted by alkalinization of cultures. Pectin lyase had an endo mode of action, whereas pectate lyase and polygalacturonase behaved more as exoenzymes. These results are discussed in relation to the appearance of the different pectic enzymes when the fungus is confronted with a pectic polymer.Key words: Fusarium oxysporum f.sp. radicis-lycopersici, Lycopersicon esculentum, pectate lyase, pectin lyase, polygalacturonase.

Evidence countering the role of polygalacturonase in invasion of root hairs of leguminous plants by Rhizobium spp.

1968 ◽  
Vol 14 (6) ◽  
pp. 617-625 ◽  
Author(s):  
Thomas T. Lillich ◽  
Gerald H. Elkan
Keyword(s):  
Enzyme Activity ◽  
Glycine Max ◽  
Sole Carbon Source ◽  
Root Hairs ◽  
Rhizobium Japonicum ◽  
Leguminous Plants ◽  
Uninoculated Control ◽  
Rhizobium Spp ◽  
Polygalacturonase Activity

Polygalacturonase has been postulated as being involved in the invasion of the host legume by Rhizobium spp. The role of this enzyme in the invasion of Glycine max by Rhizobium japonicum was investigated. Enzyme activity of several Rhizobium spp. was assayed viscometrically and no constitutive polygalacturonase was found. The enzyme could not be induced by growth with either pectin or galactose as the sole carbon source. Extract and exudate from the roots of nodulating and nonnodulating strains of Glycine max that had been incubated with effective strains of R. japonicum failed to show any higher levels of polygalacturonase activity than did uninoculated control plants. Previously reported experiments were duplicated. Levels of polygalacturonase activity from the extract and exudate of white clover inoculated with R. trifolii Cl 226 were as reported in the literature. Contrary to published reports, however, no greater levels of enzyme activity were found from effective plant–bacteria associations than from either ineffective associations or uninoculated control plants. It was concluded from these experiments that polygalacturonase does not play a major role in the invasion of Glycine max by Rhizobium japonicum.

Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

1986 ◽  
Vol 64 (10) ◽  
pp. 2216-2226 ◽  
Author(s):  
Yves Prin ◽  
Mireille Rougier
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Root Apex ◽  
Alnus Glutinosa ◽  
Root Surface ◽  
Infection Process ◽  
Root Cap ◽  
A Cell ◽  
Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

Root hair deformation in the infection process of Alnus rubra

1983 ◽  
Vol 61 (11) ◽  
pp. 2863-2876 ◽  
Author(s):  
Alison M. Berry ◽  
John G. Torrey
Keyword(s):  
Root Hair ◽  
Cell Walls ◽  
Root Hairs ◽  
Infection Process ◽  
Alnus Rubra ◽  
Pseudomonas Cepacia ◽  
Developmental Studies ◽  
Experimental Conditions ◽  
Root Hair Cell ◽  
Root Hair Deformation

Structural and cell developmental studies of root hair deformation in Alnus rubra Bong. (Betulaceae) were carried out following inoculation with the soil pseudomonad Pseudomonas cepacia 85, alone or in concert with Frankia, and using axenically grown seedlings. Deformational changes can be observed in elongating root hairs within 2 h of inoculation with P. cepacia 85. These growing root hairs become branched or multilobed and highly modified from the single-tip growth of axenic root hairs. The cell walls of deformed hairs are histologically distinctive when stained with the fluorochrome acridine orange. Filtrate studies using P. cepacia 85 suggest that the deforming substance is not a low molecular weight compound. Root hair deformation and the associated wall histology are host specific in that Betula root hairs show none of these responses when grown and inoculated in the experimental conditions described. The bacterially induced changes in root hair cell walls during deformation may create a chemically and physically modified substrate for Frankia penetration, and the deformation itself may serve to entrap and enclose the filamentous organism, allowing wall dissolution and entry. Thus these events represent a complex host response as a precondition to successful nodulation.

scholarly journals Host Specificity In The Root Hair "Curling Factor" of Rhizobium Spp.

1969 ◽  
Vol 22 (2) ◽  
pp. 413 ◽  
Author(s):  
Phaik Y Yao ◽  
JM Vincent
Keyword(s):  
Medicago Sativa ◽  
Host Specificity ◽  
Root Hair ◽  
Root Zone ◽  
Root Hairs ◽  
Degree Of Deformation ◽  
Medicago Sativa L ◽  
Rhizobium Spp ◽  
Hair Curling ◽  
Root Hair Curling

Thirty-eight cultures of rhizobia and 10 non-rhizobia growing in the root zone of clover (Trifolium glomeratum L.), 5 rhizobia and 3 non-rhizobia in that of lucerne (Medicago sativa L.), and 8 rhizobia in that ofSiratro (Phaseolus atropurpureus DO.) revealed a specific relationship between bacteria and host that determined the kind and degree of deformation of the root hairs.

Production and Thermal Characterization of an Alkaline Pectin Lyase from Penicillium notatum

2015 ◽  
Vol 11 (4) ◽  
pp. 517-525 ◽  
Author(s):  
Umme Habibah Siddiqua ◽  
Haq Nawaz Bhatti ◽  
Shazia Nouren ◽  
Saima Noreen ◽  
Ismat Bibi
Keyword(s):  
Ammonium Sulphate ◽  
Thermal Inactivation ◽  
Thermal Characterization ◽  
Maximal Activity ◽  
Inhibitory Effect ◽  
Pectin Lyase ◽  
Partial Purification ◽  
Penicillium Notatum ◽  
Enhanced Production ◽  
Lyase Activity

Abstract The present study was aimed to investigate the potential of Penicillium notatum for the production of pectin lyase under solid state culture using wheat bran as substrate. Different process parameters were optimized using completely randomized design for enhanced production of the pectin lyase. P. notatum showed maximum production (1875 U/gds) of pectin lyase with substrate amount 15 g/250 ml, moisture level 60%, pH 6, incubation period 120 h at 30°C. Pectin lyase activity was further improved with the addition of maltose and ammonium sulphate as carbon and nitrogen additives (1%), respectively. Partial purification of enzyme was carried out by ammonium sulphate precipitation at 80% saturation level. The P. notatum pectin lyase showed maximal activity at 65°C and pH 8. Km and Vmax values were 0.29% and 0.487 µmol/min, respectively. Energy of activation was found to be 5.33 kJ/mol. A detailed kinetic study of thermal inactivation was carried out. The results showed that pectin lyase exhibited resistance against thermal unfolding. Effect of various metals on pectin lyase activity was also investigated. All the metals showed inhibitory effect on the enzyme activity. The present investigation revealed that pectin lyase isolated from P. notatum is thermally stable and alkaline in nature.

Plasmid replicons of Rhizobium

2005 ◽  
Vol 33 (1) ◽  
pp. 157-158 ◽  
Author(s):  
L.C. Crossman
Keyword(s):  
Short Review ◽  
Nitrogen Fixing ◽  
Rhizobium Etli ◽  
Free Living ◽  
Leguminous Plants ◽  
Symbiotic Plasmid ◽  
Rhizobium Spp ◽  
Plasmid Replicons ◽  
Rhizobium Sp

Rhizobium spp. are found in soil. They are both free-living and found symbiotically associated with the nodules of leguminous plants. Traditionally, studies have focused on the association of these organisms with plants in nitrogen-fixing nodules, since this is regarded as the most important role of these bacteria in the environment. Rhizobium sp. are known to possess several replicons. Some, like the Rhizobium etli symbiotic plasmid p42d and the plasmid pNGR234b of Rhizobium NGR234, have been sequenced and characterized. The plasmids from these organisms are the focus of this short review.

Pectin Lyase Activity in Culture Medium of Lasidioplodia theobromae

2007 ◽  
Vol 2 (3) ◽  
pp. 334-340 ◽  
Author(s):  
A.O. Adejuwon ◽  
P.O. Olutiola .
Keyword(s):  
Culture Medium ◽  
Pectin Lyase ◽  
Lyase Activity
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