scholarly journals A model for the development of the rhizobial and arbuscular mycorrhizal symbioses in legumes and its use to understand the roles of ethylene in the establishment of these two symbioses

2002 ◽  
Vol 80 (7) ◽  
pp. 695-720 ◽  
Author(s):  
F C Guinel ◽  
R D Geil
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Cell Layer ◽  
Cortical Cell ◽  
Arbuscular Mycorrhizal ◽  
Nod Factors ◽  
Pisum Sativum L ◽  
Rhizobial Symbiosis ◽  
Nodulation Mutants ◽  
Sites Of Action ◽  
Root Tissues

We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis – outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants.Key words: AM, epidermis, evolution, pea, rhizobia, sym mutant.

scholarly journals LysM Receptor-Like Kinase LYK9 of Pisum Sativum L. May Regulate Plant Responses to Chitooligosaccharides Differing in Structure

2021 ◽  
Vol 22 (2) ◽  
pp. 711
Author(s):  
Irina V. Leppyanen ◽  
Olga A. Pavlova ◽  
Maria A. Vashurina ◽  
Andrey D. Bovin ◽  
Alexandra V. Dolgikh ◽  
...  
Keyword(s):  
Immune Response ◽  
Pisum Sativum ◽  
Binding Capacity ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Phytopathogenic Fungi ◽  
Plant Responses ◽  
Pisum Sativum L ◽  
Receptor Like Kinase ◽  
Pea Mutants

This study focused on the interactions of pea (Pisum sativum L.) plants with phytopathogenic and beneficial fungi. Here, we examined whether the lysin-motif (LysM) receptor-like kinase PsLYK9 is directly involved in the perception of long- and short-chain chitooligosaccharides (COs) released after hydrolysis of the cell walls of phytopathogenic fungi and identified in arbuscular mycorrhizal (AM) fungal exudates. The identification and analysis of pea mutants impaired in the lyk9 gene confirmed the involvement of PsLYK9 in symbiosis development with AM fungi. Additionally, PsLYK9 regulated the immune response and resistance to phytopathogenic fungi, suggesting its bifunctional role. The existence of co-receptors may provide explanations for the potential dual role of PsLYK9 in the regulation of interactions with pathogenic and AM fungi. Co-immunoprecipitation assay revealed that PsLYK9 and two proposed co-receptors, PsLYR4 and PsLYR3, can form complexes. Analysis of binding capacity showed that PsLYK9 and PsLYR4, synthesized as extracellular domains in insect cells, were able to bind the deacetylated (DA) oligomers CO5-DA–CO8-DA. Our results suggest that the receptor complex consisting of PsLYK9 and PsLYR4 can trigger a signal pathway that stimulates the immune response in peas. However, PsLYR3 seems not to be involved in the perception of CO4-5, as a possible co-receptor of PsLYK9.

Vesicular – arbuscular mycorrhizae in disturbed and revegetated sites from La Gran Sabana, Venezuela

1992 ◽  
Vol 70 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Gisela Cuenca ◽  
Milagros Lovera
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Plant Cover ◽  
Ground Cover ◽  
Arbuscular Mycorrhizal ◽  
Most Probable Number ◽  
Probable Number ◽  
Organic Layers ◽  
Vesicular Arbuscular Mycorrhizae ◽  
Disturbed Areas ◽  
Vesicular Arbuscular

Savannas growing on stony, old and nutrient-poor soils of southern Venezuela were severely disturbed by removal of the soil organic layers with bulldozers for road building. Introduced species Brachiaria decumbens, Brachiaria humidicola, Pueraria phaseoloides, and Calopogonium sp. were sown. The substrate was fertilized and limed. Plant cover, vesicular – arbuscular mycorrhizae colonization, spore number, and most probable number of propagulels in undisturbed savanna, disturbed nonrevegetated savanna, and six revegetated savannas were assessed. The perturbation reduced the mycorrhizal propagule number in comparison with the undisturbed savanna. In the nonrevegetated areas the mean percent ground cover 2 years after disturbance was low (0.04%). In revegetated areas an increase in mycorrhizal propagule number occurred and the mycorrhizal colonization of the sown species was high. In restored areas there was an increase in species of nonmycotrophic Amaranthaceae. The results support other predictions on the mycorrhizae in successional biomes, because in the extremely nutrient-poor soils studied the colonizing species were mainly mycotrophic. The reclamation program applied in disturbed areas was useful because it has allowed the recovery of vesicular – arbuscular mycorrhizal inoculum and there was an increase in the recolonization of native plants. Key words: disturbance, endomycorrhizae, revegetation, savanna, vesicular – arbuscular mycorrhizae.

Early Periderm Ontogeny in Fraxinuspennsylvanica, Ailanthusaltissima, Robiniapseudoacacia, and Pinusresinosa, Seedlings

1972 ◽  
Vol 2 (2) ◽  
pp. 135-143 ◽  
Author(s):  
G. A. Borger ◽  
T. T. Kozlowski
Keyword(s):  
Cell Layer ◽  
Cortical Cell ◽  
Cortical Cells ◽  
Mother Cells

The subepidermal cell layer was the site of origin of the first periderm in the hypocotyl and internodes of Fraxinuspennsylvanica and Ailanthusaltissima. In the hypocotyl of Robiniapsendoacacia, the first periderm arose in cortical cells near the phloem; in the internodes it originated in the subepidermal, second, or third cortical cell layer. The outermost cell layer of the pericycle gave rise to the first periderm in the hypocotyl of Pinusresinosa. In all four species, periderm appeared first near the base of the hypocotyl and developed acropetally. In A. altissima and R. pseudoaeacia, phellem mother cells were cut off by the phellogen. These subsequently divided to produce phellem cells. In F. pennsylvanica and P. resinosa, phellem cells were produced directly from the phellogen.

Dual mycorrhizal symbiosis: an asset for eucalypts out of Australia?

2017 ◽  
Vol 47 (4) ◽  
pp. 500-505 ◽  
Author(s):  
Djamila Adjoud-Sadadou ◽  
Rosa Halli-Hargas
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Dry Season ◽  
Mycorrhizal Symbiosis ◽  
Limiting Factor ◽  
Wet Season ◽  
Opposite Pattern ◽  
Symbiotic Associations ◽  
Mycorrhizal Status ◽  
Old Trees

The dual symbiotic habit of the genus Eucalyptus is well documented: while arbuscular mycorrhizae are always dominant in seedlings and young trees, they are replaced by ectomycorrhizae in older trees. Here, the mycorrhizal status of eucalypts of different ages was assessed over the year in three plantations in the humid Mediterranean climate zone of Algeria (using morphological, anatomical, and histological criteria) and quantified in the dry and wet seasons over three years (using the grid-line intersect method of Giovannetti and Mosse (1980, New Phytol. 84: 489–500, doi: 10.1111/j.1469-8137.1980.tb04556.x ) on randomized fine root segments). Unexpectedly, the results revealed the persistence of arbuscular mycorrhizae in old trees and their dominance over ectomycorrhizae during the dry season, while the opposite pattern was observed in the wet season. Composite mycorrhizae displaying intimately mixed arbuscular mycorrhizae and ectomycorrhizae anatomical structures also occurred and were more frequent during the dry season. Eucalypts were clearly able to form a wide diversity of symbiotic associations with arbuscular mycorrhizal and ectomycorrhizal fungi locally associated with native trees, shrubs, and herbaceous plants. Therefore, the mycorrhizal status should not be a limiting factor to the silviculture of eucalypts in this area of Algeria because the dual symbiotic habit provides complementary benefits in a poor soil and in an alien environment.

The effect of glyphosate on resistance of tomato to Fusarium crown and root rot disease and on the formation of host structural defensive barriers

1988 ◽  
Vol 66 (8) ◽  
pp. 1547-1555 ◽  
Author(s):  
R. A. Brammall ◽  
V. J. Higgins
Keyword(s):  
Cortical Cell ◽  
Sublethal Concentration ◽  
Aminooxyacetic Acid ◽  
Induced Susceptibility ◽  
Tomato Seedlings ◽  
Crown And Root Rot ◽  
Rot Disease ◽  
Severity Of The Disease ◽  
Root Tissues ◽  
Herbicide Glyphosate

Colonization of root tissues in tomato seedlings genetically resistant to Fusarium oxysporum f.sp. radicis-lycopersici Jarvis & Shoemaker occurred following exposure to a sublethal concentration of the herbicide glyphosate (1.0 mM for 24 h prior to inoculation). The glyphosate-induced colonization was associated with an inefficiency in incorporation of phenolic materials into the papillae and into the modified cortical cell walls normally formed in response to this pathogen. Glyphosate-induced susceptibility decreased when the glyphosate was applied at 24 or 48 h after inoculation. Plants supplied with exogenous L-phenylalanine failed to exhibit reduced susceptibility after glyphosate exposure. In radial growth bioassays, growth of the fungus was unaffected by 4.0 mM glyphosate. α-Aminooxyacetic acid, an inhibitor of phenylalanine ammonia lyase, also increased the severity of the disease in resistant plants. Glyphosate also induced susceptibility to an isolate of F. solani f.sp. pisi, which was normally not pathogenic to tomato.

Influence of arbuscular mycorrhizae on soil P dynamics, corn P-nutrition and growth in a ridge-tilled commercial field

2008 ◽  
Vol 88 (3) ◽  
pp. 283-294 ◽  
Author(s):  
Christine P Landry ◽  
Chantal Hamel ◽  
Anne Vanasse
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Dry Mass ◽  
Soil Disturbance ◽  
P Uptake ◽  
P Nutrition ◽  
Soil P ◽  
High Yields ◽  
Ridge Tillage

Ridge-tilled corn (Zea mays L.) could benefit from arbuscular mycorrhizal (AM) fungi. Under low soil disturbance, AM hyphal networks are preserved and can contribute to corn nutrition. A 2-yr study was conducted in the St. Lawrence Lowlands (Quebec, Canada) to test the effects of indigenous AM fungi on corn P nutrition, growth, and soil P in field cropped for 8 yr under ridge-tillage. Phosphorus treatments (0, 17, 35 kg P ha-1) were applied to AM-inhibited (AMI) (fungicide treated) and AM non-inhibited (AMNI) plots. Plant tissue and soil were sampled 22, 48 and 72 days after seeding (DAS). P dynamics was monitored in situ with anionic exchange membranes (PAEM) from seeding to the end of July. AMNI plants showed extensive AM colonization at all P rates. At 22 DAS, AMI plants had decreased growth in the absence of P inputs, while AMNI plants had higher dry mass (DM) and P uptake in unfertilized plots. The PAEM was lower in the AMNI unfertilized soils in 1998 and at all P rates in 1999, indicating an inverse relationship between P uptake and PAEM. At harvest, grain P content of AMNI plants was greater than that of AMI plants. In 1998, only AMI plants had decreased yield in the absence of P fertilization. In 1999, AMNI plants produced greater grain yield than AMI plants at all P rates. AM fungi improve the exploitation of soil P by corn thereby maintaining high yields while reducing crop reliance on P inputs in RT. Key words: Arbuscular mycorrhizae, ridge-tillage, soil P dynamics, corn, P nutrition

Occurrence and isolation of vesicular–arbuscular mycorrhizae in cropped field soils of Saskatchewan, Canada

1993 ◽  
Vol 39 (6) ◽  
pp. 567-575 ◽  
Author(s):  
Narayan C. Talukdar ◽  
James J. Germida
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Arbuscular Mycorrhizal ◽  
Triticum Aestivum L ◽  
Wheat Roots ◽  
Wheat Field ◽  
Vesicular Arbuscular Mycorrhizae ◽  
Vesicular Arbuscular ◽  
Field Soils ◽  
Vam Colonization ◽  
Study Sites

Soil and root samples collected from fields cropped to spring wheat (Triticum aestivum L. cv. Katepwa) and lentil (Lens esculenta L. cv. Eston) at 11 sites across four soil zones of Saskatchewan were analyzed for spore numbers, level of vesicular–arbuscular mycorrhizal (VAM) colonization, and VAM species. The number of VAM spores detected in field soils ranged from 78 to 272 per 100 g soil. Vesicular–arbuscular mycorrhizae colonized wheat and lentil at all the field study sites, but levels of colonization in the two crops varied from site to site and the differences were more pronounced in wheat than in lentil. Generally, lentil both exhibited a higher percentage of VAM colonized roots and contained more arbuscules and vesicles than wheat roots. However, wheat appeared to be colonized by different types of VAM depending on the field sites. Differences in VAM colonization were not related to the moisture and temperature gradient of the four soil zones or soil properties. Seven VAM species were isolated by enriching indigenous VAM mixtures (collected from wheat field soils of six field sites) on maize. The VAM isolated most closely resembled Acaulospora denticulata, Gigaspora decipiens, Glomus clarum, Glomus etunicatum, Glomus fasciculatum, Glomus mosseae, and Glomus versiforme. The species composition of the VAM community varied at the different field sites.Key words: VAM, Acaulospora, Gigaspora, Glomus.

scholarly journals Arbuscular mycorrhizal fungi favor invasive Echinops sphaerocephalus when grown in competition with native Inula conyzae

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Veronika Řezáčová ◽  
Milan Řezáč ◽  
Hana Gryndlerová ◽  
Gail W. T. Wilson ◽  
Tereza Michalová
Keyword(s):  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizae ◽  
Native Plants ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Plant Invasions ◽  
Soil Disturbance ◽  
Mycorrhizal Networks ◽  
The Family ◽  
Globalized World

AbstractIn a globalized world, plant invasions are common challenges for native ecosystems. Although a considerable number of invasive plants form arbuscular mycorrhizae, interactions between arbuscular mycorrhizal (AM) fungi and invasive and native plants are not well understood. In this study, we conducted a greenhouse experiment examining how AM fungi affect interactions of co-occurring plant species in the family Asteracea, invasive Echinops sphaerocephalus and native forb of central Europe Inula conyzae. The effects of initial soil disturbance, including the effect of intact or disturbed arbuscular mycorrhizal networks (CMNs), were examined. AM fungi supported the success of invasive E. sphaerocephalus in competition with native I. conyzae, regardless of the initial disturbance of CMNs. The presence of invasive E. sphaerocephalus decreased mycorrhizal colonization in I. conyzae, with a concomitant loss in mycorrhizal benefits. Our results confirm AM fungi represent one important mechanism of plant invasion for E. sphaerocephalus in semi-natural European grasslands.

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