A modified procedure for staining roots to detect VA mycorrhizas
A modified technique for staining roots to detect VA mycorrhizas is described. It eliminates as many toxic compounds as possible from root fixation/staining procedures without reducing the resolution of the staining. Success has been achieved with angiosperm, fern, lycopod and psilophyte roots and bryophyte.
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Cited by (1382)
Interactions between foredune morphologies and vegetation: Exploring the occurrence of arbuscular mycorrhizal fungi
2024, Regional Studies in Marine ScienceVegetation is a key trait for understanding the foredune morphologies. However, the rhizosphere in coastal dunes imposes high levels of water and nutrient stress on plants. In these conditions, arbuscular mycorrhizal fungi (AMF) are prominent root symbionts that play a crucial role in improving to abiotic stress and promoting plant growth. On the south coast of the state of São Paulo, foredunes were studied for their floristic composition, relative frequency of AMF and grain size of rhizosphere. Foredune was classified regarding the morphology as terrace, ridge I, and ridge II. The terrace has a low height (<0.5 m) and is composed of native species canopies low (<0.2 m) and high (0.5–1.5 m) characterized by AMF colonization close to 60%. In contrast, ridge I showed wavy crests that were about 1 m high and ∼30 m wide, with a predominance of plant species with low canopy and 68% AMF colonization. The morphology ridge II reaches the greatest height (3 m), to the detriment of a smaller width (up to 15 m) and the plants present high canopy (>0.5 m) with close to 75% AMF. The increase of the relative frequency AMF from the terrace to ridges I and II may indicate that the increase of sand accumulation with continuous burial of roots is rather positive to plant growth. Yet, varied canopy heights of the plants species control the verticalization and horizontalization of the foredune. Low-canopy species, gradually slow down wind flow, causing spatialized deposition and widening. Conversely, species with highest canopies swiftly reduce wind flow due to the density of their aerial portion (leaves), resulting in deposition just below their structure fostering foredune vertical growth.
Changes induced by vesicular-arbuscular fungus Rhizophagus irregularis in aerial parts of Echinacea purpurea
2024, Scientia HorticulturaeThe majority of studies conducted on Echinacea purpurea regarding elicitor (e.g. arbuscular-mycorrhizal fungi – AMF) induction have been carried out in vitro, using controlled conditions. The application of elicitors had conducted to elevated levels of various secondary metabolites. The aim of this study was to test the competitive ability of Rhizophagus irregularis on different substrates (greenhouse and open field conditions) in the presence of local microorganism communities, in order to induce quantitative and qualitative changes in the active principles of E. purpurea. Greenhouse and open field experiments were conducted with E. purpurea inoculated with R. irregularis and control plants. In the greenhouse experiment three different soil types and sterile peat were used. Dried leaves (foliage) of E. purpurea plants were subjected to HPLC analyses to determine their phenolic compounds. The dried herba was analyzed with GC-MS for volatile oil composition. According to the HPLC analyses six phenolic acids were detected. The two dominant compounds were chicoric and chlorogenic acids. Control plants presented significantly higher values in phenolic content compared to treated plants, on sterile peat and open field Stagnic Luvisol in case of caftaric (with 59 and 48%), chlorogenic (16 and 28%), caffeic (6 and 5%), chicoric acids (51 and 56%), and echinacoside (38 and 61%). AMF colonization rate favored caftaric, chlorogenic, and chicoric acids content on several substrates. The quantitative analyses of the essential oil showed significantly higher yield for potted control plants on Stagnic Luvisol (70%). The qualitative analyses revealed 35 constituents, the most abundant were caryophyllene oxide and germacrene D. According to the PCA analyses the essential oil obtained from treated plants contained γ-cadinene and humulene epoxide-2 in higher proportions, while the essential oil of the control plants was abundant in spatulenol and shyobunol. Observations on AMF effect on root essential oil yield and composition would be of high interest. Further studies with other AMF species in combination with growth-promoting bacteria should be carried out, to assess their competitive behavior with the native microorganisms.
Transferred communities of arbuscular mycorrhizal fungal persist in novel climates and soils
2023, Soil Biology and BiochemistrySymbiotic mycorrhizal fungi strongly influence plant establishment and growth particularly in harsh environments, whereby sympatric, presumably co-adapted symbionts are considered particularly beneficial. However, the response of transferred sympatric mycorrhizal fungal communities to new environments remains largely ignored. We therefore studied the relative importance of initial inoculum, soil and climatic conditions on the composition, diversity and root colonization ability of arbuscular mycorrhizal fungal (AMF) communities. To do so, we analyzed the AMF communities in an extensive experiment with two ecotypes of Bouteloua gracilis planted in their sites of origin and in four new sites differing in climate and soil properties.
After three seasons of growth, the sympatric AMF communities were little changed by the new abiotic conditions. The composition of the AMF communities in plant roots was most strongly determined by the initial inoculum, while the contribution of divergent soil and climatic conditions was an order of magnitude smaller. The levels of root colonization by AMF, in contrast, were significantly influenced by climatic and soil conditions and did not differ among communities of different origins. Their pattern indicates that mycorrhiza formation is facilitated in the plant's sympatric soil and climatic conditions, but also that transferred AMF communities adjust mycorrhiza formation to new abiotic conditions.
Arbuscular mycorrhizal fungi can reduce severity of fusariosis (Fusarium oxysporum) in cowpea plants (Vigna unguiculata (L.) Walp.)
2023, RhizosphereMycorrhizal symbiosis with arbuscular mycorrhizal fungi (AMF) provides plants with high nutrient absorption and non-nutritional benefits such as resistance to diseases. Fusariosis (Fusarium oxysporum) affects cowpea (Vigna unguiculata (L.) Walp.) production, which is a common culture in household farms in the northeast region of Brazil. The aim of this study was to evaluate the potential of native AMF from Maranhão Cerrado to provide resistance/non-nutritional benefits to cowpea plants infected with F. oxysporum f.sp. tracheiphilum. The bioassay was conducted using cowpea plants to assess their responses to different AMF species and F. oxysporum under controlled greenhouse conditions. Vegetative development of cowpeas (fresh and dry shoot and root mass, leaf number, and plant height) benefited from AMF symbiosis, especially with Claroideoglomus etunicatum and Acaulospora morrowiae. All AMF species reduced the severity score of the disease, confirming the potential use of mycorrhizal fungi species to reduce F. oxysporum damage in cowpea cultures.
Inoculation with arbuscular mycorrhizal fungi increase calcium uptake in Malus robusta
2023, Scientia HorticulturaeUtilization of plants-microbe's interactions to remediate calcium1 (Ca) deficiency soils is effective and practical. A greenhouse pot experiment was conducted to evaluate the effect of arbuscular mycorrhizal fungi2 (AMF) inoculation and the synergy of AMF and Ca fertilizer on physiological and transcriptomic responses in apple rootstock (Malus robusta) roots. AMF and Ca fertilizer synergistically served to elongate root length, surface area, average stem diameter and biomass, such extended the surface area in contact with soil nutrients and water. Symbiosis of AMF with apple seedlings made significantly higher levels of Ca in root tissue and promoted Ca translocation from roots to shoot tissue. GO and KEGG pathway analysis disclosed that gene expression varies in several critical gene families, such as auxin response (MdAux/IAAs, MdGH3 and MdSAUR), TCA cycles (MdCS, MdMDH and MdACO), phosphate transporters (MdPHT1;1, MdPHT1;10 and MdPHT1;3) and Ca2+ signal transduction pathways (MdCa2+/ATPase, MdCML, MdTPC1 and MdCDPK), indicating that apple regulates the expression of genes related to auxin synthesis, organic acid secretion, and calcium transporters and channels, thereby increased the growth of apple roots and promoted the secretion of organic acids, resulting in the increase of calcium effectiveness in soil. AMF promoted the accumulation and utilization of Ca in plants by regulating the expression levels of genes related to these pathways. These results contribute to a better understanding of AMF symbiosis mechanism behind the Ca uptake of apple seedlings under exogenous Ca treatment.
Unraveling the mechanisms of drought tolerance enhancement in Sorghum bicolor through Glomus mosseae inoculation: Insights from comparative analysis of Super 2 and Konawe Selatan accessions
2023, South African Journal of BotanyThe increasing frequency of droughts due to climate change has negatively impacted crop yield. This research aimed to study the mechanism of Glomus mosseae in improving the drought tolerance of Sorghum bicolor plants, specifically in Super 2 (S2) and Konawe Selatan (KS) accession. G. mosseae was used to inoculate the plants grown in the sterile zeolite. The drought was imposed in two cycles by suspending irrigation for six days per cycle. After nine weeks, the plants were harvested and subjected to various analyses. The results showed that drought stress lowered biomass, pigment concentrations by 45% and 23%, and leaf relative water content (RWC) by 34% and 17% for S2 and KS accessions, respectively. Conversely, malondialdehyde (MDA) levels rose by 20% and 9%, while proline synthesis was improved by 7% and 16% on S2 and KS, respectively, compared to the control. In contrast, inoculation with G. mosseae markedly augmented chlorophyll levels by 85% and 25%, elevated leaf relative water content by 33% and 8%, and enhanced P content by 20% and 19% for S2 and KS accessions, respectively, when compared to drought-exposed treatments. Additionally, G. mosseae inoculation preserved root length, biomass, leaf number, proline synthesis, and nitrogen content, while inducing a reduction in MDA levels by 11% and 6% in S2 and KS, respectively, in relation to the drought treatments. G. mosseae improves sorghum's drought tolerance by reducing water loss through improving water and nutrient uptake via external hyphae and enhancing photosynthetic properties via pigment protection. Furthermore, it was shown that G. mosseae is highly efficient at maintaining proline balance and enhancing the effectiveness of both enzymatic and non-enzymatic antioxidants to eliminate reactive oxygen species (ROS). KS accession exhibited elevated levels of nitrogen content, leaf number, upper ground biomass, chlorophyll and RWC. Conversely, the Super 2 accession manifested higher levels of lower ground biomass, root length, root colonization and phosphorus content. The addition of G. mosseae to the soil shows great potential as a sustainable agricultural approach under climate change conditions, specifically for the promotion of sorghum plant survival under drought stress. This potential stems from the ability of G. mosseae to enhance key plant properties, including photosynthetic performance and water balance regulation, through the expansion of extraradical hyphal growth. Moreover, G. mosseae supplementation maintains proline levels, enhances nutrient uptake and detoxifies reactive oxygen species by promoting antioxidant capacity. As a result of these properties, sorghum plants exhibit increased biomass and resistance to drought stress, providing an important tool for future sustainable agriculture under climate change.