Mostra el registre complet de l'element. Successful arbuscular mycorrhizal fungi AMF symbiosis in sand dunes is a key factor for the maintenance of stable vegetation. Therefore, the main goal of this work was to study the AMF species associated with sand dunes in the Gulf of Valencia Spain , as well as the effects of environmental and temporal factors on these AMF communities. In order to achieve these, soil samples from the rhizosphere of four plant species were seasonally collected at 6 sites during 2 years in three habitats. Frequency and relative abundance of AMF among these samples were examined. Among the ten AMF species identified, only Corymbiglomus corymbiforme and Diversispora aurantia Diversisporaceae had been previously described.
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Anatomical description of the arbuscular mycorrhizal fungi colonization in two tree legumes. Solenny M. Norberto M. Maciel-De Sousa 1. Sanabria-Chopite 1. Calle 1 entre Av.
Cabudare, Lara, Venezuela. The arbuscular mycorrhizal association is the symbiosis between fungi and the roots of plants, which contributes to maintaining ecosystems in a sustainable manner.
To describe the colonization of three arbuscular mycorrhizal fungi AMF inoculated in two tree legumes and to determine the morphological type of the symbiotic association. The seeds of Pithecellobium dulce Roxb. Howeler, Sieverd. Schenck C. At days, the secondary roots were sampled, clarified and stained with acid fuchsin and trypan blue. The fungal structures were observed under an optical microscope and the colonization percentage was determined.
Thin, transparent and cenocitic hyphae, as well as hylopodia and arbuscules, were observed. The morphological association in the two arboreal species was mainly from the Paris type, with occasional presence of the type Arum. The inocula of the AMF established high symbiotic association with the legumes studied.
The applied techniques evidenced the structures of the AMF inside the root and allowed to identify the morphological association of the symbionts. The arbuscular mycorrhizal association is a symbiosis between fungi and the root system of plants.
On the other hand, fungi require the host plant to complete the life cycle. As colonization progresses through the root, the fungal structures develop into two types of association called Arum and Paris. In the first, the hypha grows intercellularly in the cortex, longitudinally to this tissue and penetrates with short branches in the cells forming arbuscules in its interior.
In the Paris type, the intracellular coiled hyphal; it does not always originate arbuscules capable of interacting with the cytoskeleton. Smith and Smith determined the type of association between arbuscular mycorrhizal fungi AMF and plants, showing that the Paris type prevailed in 41 botanical families, while in another 30 families the type Arum was present; in addition, they found intermediate types in 21 families, among them, the Fabaceaes. The tree species Pithecellobium dulce Roxb. Blake are native plants capable of withstanding the adverse conditions that characterize the semiarid zone of Lara, Venezuela.
The fresh seeds of P. A strategy that guarantees the survival of tree species, given the stress conditions of transplanting and establishment in urban wooded areas, is the inoculation with AMF at the initial stages in nursery.
The objectives of the present study were to describe the colonization of the AMF Rhizophagus manihotis R. Sanders, inoculated in plants of yacure P. The annual precipitation of the place is mm with average annual temperature of The mature fruits of P. The fruits were processed to select seeds based on size, degree of formation, coloration, absence of malformations and apparent symptoms of diseases.
In containers designed to produce forest trees, substrate with mixture of coconut sawdust, rice husk and sandy loam 1: 1: 1 pasteurized was added. A seed was sown in each container. The design of experiments was completely random; each treatment consisted of 40 experimental units. At days after sowing das , the secondary roots of 20 plants, selected at random, were subjected to the clarification process with the methodology of Phillips and Hayman The roots were divided into two groups and stained with acid fuchsin and trypan blue.
The roots were placed on the slide in vertical position. Colonization was described through observations with an optical microscope Olympus CX21, China of x and x magnification. The mycorrhizal structures hyphae, arbuscules and vesicles were quantified by the following formulas:. The stained roots were cross-sectioned by freehand. Fungal structures were described in each segment and section.
The information was necessary to define the morphological type of the association. The colonization percentage data was analyzed by analysis of variance after checking the statistical assumptions of the completely random design, using the program Statistix version 8. Analytical Software, Table 1 shows the results of colonization and development of AMF structures in P. At das, R. Rhizophagus manihotis and F. It should be noted that S.
The fungal structures were quantified in root segments at days after sowing. The highest percentage of colonization corresponded to the treatment where R. In the case of F.
This suggests that the spores used in the tests had adequate conditions for germination and, as indicated by these authors, the fungi behaved like good colonizers. The results demonstrated the affinity between AMF and P. Morong, Inga laurina Sw.
Delile, Albizia lebbeck L. Pierre, Dalbergia sissoo Roxb. With respect to the percentage of arbuscules, the fluctuation between the treatments with R. On the other hand, the low percentage of vesicles determined in this study Figure 1 illustrates the colonization of the arbuscular mycorrhizal fungi R.
The colonization in P. The hyphae formed thickened hifopodia, which were the means of penetration through or between the rhizodermal cells Figure 1B. These observations coincided with those described by Garriock, Petersonm, and Ackerley , who considered that these structures are similar to those of pathogenic fungi. The inter and intracellular hyphae developed from the penetration points Figures 1B and 1D in circumferential and longitudinal directions, crossing the cortical parenchyma, without reaching the vascular cylinder Figures 1F and 1G.
According to the development of the intraradical mycelium, the morphological behavior observed in P. During the first phase of colonization, the second morphological type was predominant in the circumferential direction, since the fungal symbiont propagated in the cortical parenchyma by means of intracellular hyphae of considerable thickness Figure 1F ; subsequently, arbuscules were formed as terminal structures within the cells, in addition to intercellular spirals Figure 1C.
The arbuscular interfaces in Arum and Paris were similar. In the arbuscules, the trunk or base could be distinguished, while the ends were divided dichotomically Figure 1 E. Although the function of hyphae rolled into the type Paris is still uncertain, Cavagnaro, Smith, Ayling, and Smith stated that they provide an interfacial area as wide as arbuscules, which could be related to the transfer of nutrients in plant species tolerant to environmental stress and slow growth.
On the other hand, Hawley and Dames considered that the host could determine the dominant morphological type, indicating that the different structures are no more than adaptations for fungi survirval. Table 2 presents the results of the colonization of R. The percentage of hyphae, arbuscules and vesicles was also similar in the three treatments. The interaction and bidirectional exchange between the plant and the mycorrhizal fungi were evidenced with a satisfactory percentage of arbuscules in each treatment.
The lowest value was The importance of the presence of arbuscules lies in the fact that these structures participate directly in the transport of compounds necessary for the development of the plant and fungi Ortas, The percentages of intraradical vesicles were These values allowed to infer that the interaction between P.
The low values are due to the fact that the vesicles are formed with the purpose of storing reserve substances, so they are less perceived until fungi are fully established. The results showed that the level of association of P. The mycorrhizal relationship of P. For individuals of the Fabaceae family, high percentages of colonization by mycorrhizal fungi have been reported. Kunth ex Walp. On the other hand, Sylvia, Alagely, Kent, and Mecklenburg determined that plants that grow in containers have a greater percentage of colonization than those that grow in open spaces, as observed in Acacia farnesiana L.
The percentages of arbuscules in P. The inoculation with AMF caused satisfactory results; however, there was no constant prevalence of one mycorrhizal fungus over another, although the colonization rates were high. Figure 2 shows the colonization of the arbuscular mycorrhizal fungi S.
In the longitudinal and transverse sections of roots of P. In the roots the presence of spores and hifopodia in the rhizodermis was evidenced, which initiated the intraradical colonization Figures 2C , 2E and 2F ; subsequently, the hyphae branched extending from the exodermis to the region of the central cylinder Figure 2H.
Sbrana and Giovannetti and Zhu et al. During intraradical colonization in P. Colonization spread from one cell to another and spirals formed to produce intercellular rollers Figures 2D and 2G ; these characteristics corresponded to the type Paris.
The development of the hyphae extended longitudinally intercellularly and at the level of the bark. The hyphae formed, at certain intervals, lateral branches that penetrated the cell wall; they branched dichotomically causing arbuscules Figure 2C ; and, despite the ephemeral life cycle, they followed the pattern established for the Arum morphological type.
The arbuscular interface was similar in the Arum and Paris morphological types. In the opinion of Armstrong and Peterson , the coiled hyphae of Paris interact with the cytoskeleton and are separated from the cytoplasm of the host cells by an interfacial matrix, formed in the apoplastic compartment, showing this similarity with Arum mycorrhiza. It should be noted that the interface of the intercellular hyphae contributes significantly to the release of phosphorus to the host cells.
Apparently, the expression of one or another morphological development of AMF is strongly controlled by the host plant Matekwor et al. Urcelay, Tecco, and Chiarini affirmed that the intermediate types between Arum and Paris present characteristics formed by the same AMF species and that the formation of mycorrhizal structures in the roots is determined by the interaction of the species of plants and fungi involved.
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Biotechnology and Bioengineering, Cinvestav, Av. The inoculation of several species of micropropagated plantlets with native diazotrophic bacteria and arbuscular mycorrhizal fungi has been reported to increase growth and survival percentage compared to plantlets without inoculation. The survival of in vitro developed potato Solarium tuberosum L. Alfa plantlets co-inoculated with Glomus fasciculatum Thaxter sensu Gerd. Plantlets were then transferred to near-commercial greenhouse and plant growth and minitubers yield were determined 15 weeks after ex vitro growth. Survival of the plantlets at room temperature doubled when inoculated with the two AM fungi and also biomass and minituber yield of plants compared to untreated plants.
Diversity of arbuscular mycorrhizal fungi amf and mycorrhizal potential of the soil from a natural and a disturbed savannah from la gran sabana, venezuela. INCI [online]. ISSN The benefits provided by arbuscular mycorrhizas AM to plants are well known, especially those related to the improvement of mineral nutrition and protection against root pathogens, among others. However, recent evidence has arisen about the influence of the diversity of AM fungi AMF on the productivity, diversity, competitive relationships and functioning of natural ecosystems. In addition, there are evidences that support the idea that AMF diversity is severely affected by disturbance and that some AMF are particularly sensitive to human activities. The aim of this work is to compare the diversity of AMF and the mycorrhizal soil potential of an undisturbed savannah from La Gran Sabana, Bolivar state, Venezuela, with an adjacent disturbed savannah.