The action of sodium nitrate upon the infection of Lucerne root-hairs by nodule bacteria

doi:10.1098/rspb.1936.0017

Cited by 48 publications

(17 citation statements)

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“…IAA increases the plasticity of cell walls (Galston & Purves, 1960), and is produced by nodule bacteria (Link, 1937;Kefford, Brockwell & Zwar, 1960). According to Thornton (1936) the deformation of root hairs, which is believed to be caused by bacterial IAA, is a necessary prelude to infection. However, our present knowledge of the action of IAA on cell walls-which might involve an immobilization of pectin methylesterase (Glasziou, 1957;Fiihraeus & Ljunggren, 1959)-are too vague to permit detailed conclusions about the role of…”

Section: Discussionmentioning

confidence: 99%

The Role of Polygalacturonase in Root-Hair Invasion by Nodule Bacteria

Ljunggren¹,

Fåhræus²

1961

Journal of General Microbiology

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SUMMARYThe production of pol ygalacturonase in associations of nodule bacteria and seedlings of leguminous plants was investigated. Plants and bacteria were combined in the following ways : ( a ) different plant species were combined with infective strains (isolated from the same cross inoculation group) as well as non-infective ones (from foreign groups) ; ( b ) host plant species with different susceptibilities were combined with the same bacterial strain; ( c ) bacterial strains with different infectivities, as measured by the number of infection sites, were combined with the same host species; ( d ) clover strains which had lost their infectivity, as well as transformed and again infective subcultures of these strains, were tested on clover plants. The results indicate that infection of the seedlings was strongly correlated with the production of polygalacturonase. The conclusion is drawn that polygalacturonase plays an important part in the infection process. This function is thought to be a weakening of the cell wall of the root hair which would facilitate the bacterial invasion. The possible role also of indolyl-$-acetic acid in the infection process is discussed.

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Section: Discussionmentioning

confidence: 99%

The Role of Polygalacturonase in Root-Hair Invasion by Nodule Bacteria

Ljunggren¹,

Fåhræus²

1961

Journal of General Microbiology

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“…In spinach (Spinacea oleracea), root hair length was 7-fold higher at 0.01 mM NO 3 − compared to 1 mM (Foehse and Jungk, 1983). Foehse and Jungk did not report the effect of NO 3 − on root hair density, but other studies have shown negative effects on root hair numbers in oil-seed rape (Bhat et al, 1979), alfalfa (Medicago sativa) (Thornton, 1936) and Casuarina cunninghamiana (Kohls and Baker, 1989).…”

Section: Root Hair Length and Densitymentioning

confidence: 99%

“…There are many reports that root hair development is also negatively affected by the NO 3 − supply (Boot and Mensink, 1990;Foehse and Jungk, 1983;Kohls and Baker, 1989;Robinson and Rorison, 1987;Thornton, 1936). In spinach (Spinacea oleracea), root hair length was 7-fold higher at 0.01 mM NO 3 − compared to 1 mM (Foehse and Jungk, 1983).…”

Section: Root Hair Length and Densitymentioning

confidence: 99%

The nutritional control of root development

Forde

Lorenzo

2002

Interactions in the Root Environment: An Integrated Approach

221

254

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Root development is remarkably sensitive to variations in the supply and distribution of inorganic nutrients in the soil. Here we review examples of the ways in which nutrients such as N, P, K and Fe can affect developmental processes such as root branching, root hair production, root diameter, root growth angle, nodulation and proteoid root formation. The nutrient supply can affect root development either directly, as a result of changes in the external concentration of the nutrient, or indirectly through changes in the internal nutrient status of the plant. The direct pathway results in developmental responses that are localized to the part of the root exposed to the nutrient supply; the indirect pathway produces systemic responses and seems to depend on long-distance signals arising in the shoot. We propose the term 'trophomorphogenesis' to describe the changes in plant morphology that arise from variations in the availability or distribution of nutrients in the environment. We discuss what is currently known about the mechanisms of external and internal nutrient sensing, the possible nature of the long-distance signals and the role of hormones in the trophomorphogenic response.Abbreviations: ABA, abscisic acid; NR, nitrate reductase; P i , inorganic phosphate

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“…The relatively short time from inoculation to production of detectable nodules makes it much easier to use than the red clover and lucerne systems (17,22,23). The highly efficient nodulation removes the necessity for large numbers of plants for a single treatment.…”

Section: Resultsmentioning

confidence: 99%

“…Before nodulation, the surface of the root is covered with a matrix of bacteria (7). Groups of bacteria at the tips of roots have also been noted (23,25 various legumes. This work is also concerned with both nodulation and effectiveness of nitrogen fixation.…”

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confidence: 94%

Chemotaxis of Rhizobium spp. to Plant Root Exudates

Currier¹,

Strobel²

1976

Plant Physiol.

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Rhizobium spp. show chemotaxis to plant root exudates. Both legumes and non-legume root exudates attract the different rhizobia studied. However, the bacteria show a differential response in that they are attracted to the root exudates of some plants and show no attraction toward others. An example of negative chemotaxis was also observed.The trefoil strain of Rhizobium shows chemotaxis which is qualitatively different from that observed in other bacteria in that simple sugars, diand trisacchandes, dextrans, and amino acids do not attract this bacterium.The bacteria which nodulate legumes, Rhizobium spp., are specific in that a single strain of the bacterium can only infect certain species, or even certain varieties within a species, of legume (4). This specificity is the basis of species differentiation in Rhizobium as well as the cross inoculation groups in legumes (4,6,16), that is groups of legume species nodulated by a single species of Rhizobium. The mechanistic basis of bacteria-host specificity is unknown. It has been suggested that the basis for the specificity of Rhizobium is governed by the ability of the bacterium to induce polygalacturonase specifically in the roots of compatible hosts (11). This induced polygalacturonase would partially hydrolyze the root hair cell wall allowing penetration of the bacteria. Others (10, 21) failed to demonstrate enhanced polygalacturonase or pectinase production in several legumes inoculated with either infective or noninfective strains of Rhizobium.Recently, it has been suggested that legume lectins may play a part in the specificity of Rhizobium-legume root nodule symbiosis. Bohlool and Schmidt (5) showed that the lectin from soybean bound specifically with 22 strains of Rhizobium japonicum which nodulate soybean. The lectins did not bind to any of 23 other strains of rhizobia which do not nodulate soybean. This suggests that lectins on the surface of the legume root might interact specifically with a polysaccharide on the surface of the Rhizobium which nodulates that legume.It has also been observed that a leguminous plant causes accumulation of its own particular nodule bacterium in the rhizosphere of the plant (18,19). Many more bacteria accumulate on the root surface than in the soil nearby. Before nodulation, the surface of the root is covered with a matrix of bacteria (7). Groups of bacteria at the tips of roots have also been noted (23,25 various legumes. This work is also concerned with both nodulation and effectiveness of nitrogen fixation. MATERIALS AND METHODSBacteria. Five strains of Rhizobium were received from Nitragen (3101 W. Custer Ave., Milwaukee, Wis. 53209): a trefoil strain (95C13), a sainfoin strain (116A12), a Rhizobium japonicum strain specific for soybean (61A76), and two R. meliloti strains specific for sweet clover and alfalfa (102F66) and 102F51). A cowpea strain (32A1) was received from R. Valentine, University of California, Davis. These cultures were maintained on slants of yeast extract-mannitol media (14), containing 1.5% ...

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The action of sodium nitrate upon the infection of Lucerne root-hairs by nodule bacteria

Abstract: [Plates 11, 12]

Cited by 48 publications

References 3 publications

The Role of Polygalacturonase in Root-Hair Invasion by Nodule Bacteria

The Role of Polygalacturonase in Root-Hair Invasion by Nodule Bacteria

The nutritional control of root development

Chemotaxis of Rhizobium spp. to Plant Root Exudates

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