scholarly journals Elucidating the Mechanisms Underlying Enhanced Drought Tolerance in Plants Mediated by Arbuscular Mycorrhizal Fungi

2021 ◽  
Vol 12 ◽  
Author(s):  
Shen Cheng ◽  
Ying-Ning Zou ◽  
Kamil Kuča ◽  
Abeer Hashem ◽  
Elsayed Fathi Abd_Allah ◽  
...  

Plants are often subjected to various environmental stresses during their life cycle, among which drought stress is perhaps the most significant abiotic stress limiting plant growth and development. Arbuscular mycorrhizal (AM) fungi, a group of beneficial soil fungi, can enhance the adaptability and tolerance of their host plants to drought stress after infecting plant roots and establishing a symbiotic association with their host plant. Therefore, AM fungi represent an eco-friendly strategy in sustainable agricultural systems. There is still a need, however, to better understand the complex mechanisms underlying AM fungi-mediated enhancement of plant drought tolerance to ensure their effective use. AM fungi establish well-developed, extraradical hyphae on root surfaces, and function in water absorption and the uptake and transfer of nutrients into host cells. Thus, they participate in the physiology of host plants through the function of specific genes encoded in their genome. AM fungi also modulate morphological adaptations and various physiological processes in host plants, that help to mitigate drought-induced injury and enhance drought tolerance. Several AM-specific host genes have been identified and reported to be responsible for conferring enhanced drought tolerance. This review provides an overview of the effect of drought stress on the diversity and activity of AM fungi, the symbiotic relationship that exists between AM fungi and host plants under drought stress conditions, elucidates the morphological, physiological, and molecular mechanisms underlying AM fungi-mediated enhanced drought tolerance in plants, and provides an outlook for future research.

New Forests ◽  
2018 ◽  
Vol 50 (4) ◽  
pp. 593-604 ◽  
Author(s):  
Zhongfeng Zhang ◽  
Jinchi Zhang ◽  
Guangping Xu ◽  
Longwu Zhou ◽  
Yanqiong Li

2015 ◽  
Vol 28 (4) ◽  
pp. 408-419 ◽  
Author(s):  
Zhilei Liu ◽  
Yuanjing Li ◽  
Lina Ma ◽  
Haichao Wei ◽  
Jianfeng Zhang ◽  
...  

Mitogen-activated protein kinase (MAPK) cascades play important roles in the stress response in both plants and microorganisms. The mycorrhizal symbiosis established between arbuscular mycorrhizal fungi (AMF) and plants can enhance plant drought tolerance, which might be closely related to the fungal MAPK response and the molecular dialogue between fungal and soybean MAPK cascades. To verify the above hypothesis, germinal Glomus intraradices (syn. Rhizophagus irregularis) spores and potted experiments were conducted. The results showed that AMF GiMAPKs with high homology with MAPKs from Saccharomyces cerevisiae had different gene expression patterns under different conditions (nitrogen starvation, abscisic acid treatment, and drought). Drought stress upregulated the levels of fungi and soybean MAPK transcripts in mycorrhizal soybean roots, indicating the possibility of a molecular dialogue between the two symbiotic sides of symbiosis and suggesting that they might cooperate to regulate the mycorrhizal soybean drought-stress response. Meanwhile, the changes in hydrogen peroxide, soluble sugar, and proline levels in mycorrhizal soybean as well as in the accelerated exchange of carbon and nitrogen in the symbionts were contributable to drought adaptation of the host plants. Thus, it can be preliminarily inferred that the interactions of MAPK signals on both sides, symbiotic fungus and plant, might regulate the response of symbiosis and, thus, improve the resistance of mycorrhizal soybean to drought stress.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
María Josefina Bompadre ◽  
Mariana Pérgola ◽  
Laura Fernández Bidondo ◽  
Roxana Paula Colombo ◽  
Vanesa Analía Silvani ◽  
...  

The capacity of roots to sense soil physicochemical parameters plays an essential role in maintaining plant nutritional and developmental functions under abiotic stress. These conditions generate reactive oxygen species (ROS) in plant tissues causing oxidation of proteins and lipids among others. Some plants have developed adaptive mechanisms to counteract such adverse conditions such as symbiotic association with arbuscular mycorrhizal fungi (AMF). AMF enhance plant growth and improve transplant survival by protecting host plants against environmental stresses. The aim of this study was to evaluate the alleviation of transplanting stress by two strains ofRhizophagus irregularis(GC2 and GA5) in olive. Our results show that olive plants have an additional energetic expense in growth due to an adaptative response to the growing stage and to the mycorrhizal colonization at the first transplant. However, at the second transplant the coinoculation improves olive plant growth and protects against oxidative stress followed by the GA5-inoculation. In conclusion, a combination of two AMF strains at the beginning of olive propagation produces vigorous plants successfully protected in field cultivation even with an additional cost at the beginning of growth.


Author(s):  
Cheng Gao ◽  
Pierre-Emmanuel Courty ◽  
Nelle Varoquaux ◽  
Benjamin Cole ◽  
Liliam Montoya ◽  
...  

Arbuscular mycorrhizal fungi (AMF), the mutualistic symbionts with most crops, constitute a research system of human-associated fungi whose relative simplicity and synchrony are conducive to experimental ecology. However, little is known about the shifts in adaptive strategies of sorghum associated AMFs where strong AMF succession replaces initially ruderal species with competitive ones and where the strongest plant response to drought is to manage these AMF. First, we hypothesize that, when irrigation is stopped to mimic drought, competitive AMF species should be replaced by AMF species tolerant to drought stress. We then, for the first time, correlate AMF abundance and host plant transcription to test two novel hypotheses about the mechanisms behind the shift from ruderal to competitive AMF. Surprisingly, despite imposing drought stress, we found no stress tolerant AMF. Remarkably, we found strong and differential correlation between the successional shift from ruderal to competitive AMF and sorghum genes whose products (i) produce and release strigolactone signals, (ii) perceive mycorrhizal-lipochitinoligosaccharide (Myc-LCO) signals, (iii) provide plant lipid and sugar to AMF and, (iv) import minerals and water provided by AMF. These novel insights into host gene expression and succession of AMF show adaptive strategies evolved by AMF and their hosts and provide a rationale for selecting AMF to reduce inputs and maximize yield in commercial agriculture. Future research opportunities include testing the specifics and generality of our hypotheses by employing genetically modified host plants, and exploring additional genes underlying the adaptive strategies in natural succession.


Horticulturae ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 79 ◽  
Author(s):  
Domenico Ronga ◽  
Federica Caradonia ◽  
Enrico Francia ◽  
Caterina Morcia ◽  
Fulvia Rizza ◽  
...  

Climate change is increasing drought events and decreasing water availability. Tomato is commonly transplanted to an open field after seedling production in a nursery, requiring large volumes of water. Arbuscular mycorrhizal (AM) fungi help plants cope with drought stress; however, their effects depend on plant genotype and environmental conditions. In this study, we assessed the interactions among different tomato seedling genotypes and two AM fungi, Funneliformis mosseae and Rhizophagus intraradices, under two water regimes, full and reduced. Our results showed that F. mosseae was more effective than R. intraradices in the mitigation of drought stress both in old and modern genotypes. However, seedlings inoculated with R. intraradices recorded the highest values of leaf area. ‘Pearson’ and ‘Everton’ genotypes inoculated with F. mosseae recorded the highest values of root, leaf, and total dry weights under reduced and full irrigation regimes, respectively. In addition, ‘Pearson’ and ‘H3402’ genotypes inoculated with F. mosseae under a reduced irrigation regime displayed high values of water use efficiency. Our results highlight the importance of using AM fungi to mitigate drought stress in nursery production of tomato seedlings. However, the development of ad hoc AM fungal formulations, which consider genotype x AM fungi interactions, is fundamental for achieving the best agronomic performances.


2011 ◽  
Vol 8 (2) ◽  
pp. 214-217 ◽  
Author(s):  
Stavros D. Veresoglou ◽  
Matthias C. Rillig

Arbuscular mycorrhizal (AM) fungi represent ubiquitous mutualists of terrestrial plants. Through the symbiosis, plant hosts, among other benefits, receive protection from pathogens. A meta-analysis was conducted on 106 articles to determine whether, following pathogen infection of AM-colonized plants, the identity of the organisms involved (pathogens, AM fungi and host plants) had implications for the extent of the AM-induced pathogen suppression. Data on fungal and nematode pathogens were analysed separately. Although we found no differences in AM effectiveness with respect to the identity of the plant pathogen, the identity of the AM isolate had a dramatic effect on the level of pathogen protection. AM efficiency differences with respect to nematode pathogens were mainly limited to the number of AM isolates present; by contrast, modification of the ability to suppress fungal pathogens could occur even through changing the identity of the Glomeraceae isolate applied. N-fixing plants received more protection from fungal pathogens than non-N-fixing dicotyledons; this was attributed to the more intense AM colonization in N-fixing plants. Results have implications for understanding mycorrhizal ecology and agronomic applications.


2020 ◽  
Vol 48 (3) ◽  
pp. 1357-1368
Author(s):  
Sergio VALERIO-LANDA ◽  
Ramon ZULUETA-RODRIGUEZ ◽  
Evangelina E. QUIÑONES-AGUILAR ◽  
Liliana LARA-CAPISTRAN ◽  
Carlos ANGULO ◽  
...  

Maize is a crop important worldwide, but its production is limited to phosphorus availability in soil. Plants form a symbiotic association to improve their nutrition with arbuscular mycorrhizal fungi (AMF), which increase to absorption phosphorus (P) and the expression of transporters of the family Pht1. Few studies have focused on native maize plants and AMF. Thus, the objective of this study was to determine the morpho-physiological response and expression of phosphate Pht1 transporters in two native maize plants inoculated with Claroideoglomus etunicatum and P concentrations. The height, leaf area, dry biomass, CO2 assimilation rate, stomatal conductance, transpiration rate, intercellular CO2, water potential, greenness index, total chlorophyll, and ZEAma; Pht1;3 and ZEAma; Pht1;6 transporter expressions in maize plants under P (0.01 and 1 mM) concentrations were evaluated. The results showed that each native maize plant had a differential response in morpho-physiology and transporter expressions when they were inoculated with AMF and P. The response of maize plant was related with its genotype and phenotype plus environmental factor that influenced the AMF-host interaction, mycorrhizal colonization and soil nutrient absorption.


2019 ◽  
Vol 20 (17) ◽  
pp. 4199 ◽  
Author(s):  
Ali Bahadur ◽  
Asfa Batool ◽  
Fahad Nasir ◽  
Shengjin Jiang ◽  
Qin Mingsen ◽  
...  

Arbuscular mycorrhizal fungi (AMF) establish symbiotic interaction with 80% of known land plants. It has a pronounced impact on plant growth, water absorption, mineral nutrition, and protection from abiotic stresses. Plants are very dynamic systems having great adaptability under continuously changing drying conditions. In this regard, the function of AMF as a biological tool for improving plant drought stress tolerance and phenotypic plasticity, in terms of establishing mutualistic associations, seems an innovative approach towards sustainable agriculture. However, a better understanding of these complex interconnected signaling pathways and AMF-mediated mechanisms that regulate the drought tolerance in plants will enhance its potential application as an innovative approach in environmentally friendly agriculture. This paper reviews the underlying mechanisms that are confidently linked with plant–AMF interaction in alleviating drought stress, constructing emphasis on phytohormones and signaling molecules and their interaction with biochemical, and physiological processes to maintain the homeostasis of nutrient and water cycling and plant growth performance. Likewise, the paper will analyze how the AMF symbiosis helps the plant to overcome the deleterious effects of stress is also evaluated. Finally, we review how interactions between various signaling mechanisms governed by AMF symbiosis modulate different physiological responses to improve drought tolerance. Understanding the AMF-mediated mechanisms that are important for regulating the establishment of the mycorrhizal association and the plant protective responses towards unfavorable conditions will open new approaches to exploit AMF as a bioprotective tool against drought.


2021 ◽  
Vol 14 (3) ◽  
pp. 062-067
Author(s):  
Guang-Ming Huang ◽  
Yong-Jie Xu ◽  
Qiang-Sheng Wu

As a beneficial endophytic fungus, arbuscular mycorrhizal fungi (AMF) are widely distributed in nature and can symbiotically grow with approx. 80% of terrestrial plants, helping host plants to grow and develop with increased tolerance to various stresses. One of the most important functions of AMF is to promote the uptake of P from the soil by the host plant. The available findings explain the role of mycorrhizal fungi. For example, AMF increase the phosphorus uptake area of plant roots by improving the root architecture, and the extraradical mycelium can extend beyond the phosphorus-deprived areas that are inaccessible to the root, helping to expand new phosphorus sources. AMF also increase the secretion of phosphatases and organic acids in plant roots to improve the soil environment for accelerating the conversion of insoluble phosphorus. The phosphorus transporter protein genes expression is induced by AMF to enhance host P acquisition. The review briefly outlines these potential mechanisms and suggests outlooks for future research.


Botany ◽  
2011 ◽  
Vol 89 (4) ◽  
pp. 285-288 ◽  
Author(s):  
Antonio Illana ◽  
José M. García-Garrido ◽  
Inmaculada Sampedro ◽  
Juan A. Ocampo ◽  
Horst Vierheilig

Although most land plants are hosts for arbuscular mycorrhizal fungi (AMF), a small number of plant families are arbuscular mycorrhizal (AM) nonhosts. There are indications that strigolactone levels in root exudates of AM nonhost plants are lower than in AM host plants, and it has been shown that in the strigolactone-deficient rms1 mutant (ccd8) of the AM host plant pea, the AMF colonization of roots is highly reduced. Application of the synthetic strigolactone analogue GR24 to this strigolactones-deficient mutant restored AMF colonization of roots. Our objective was to determine whether the application of GR24 to AM nonhost plants can affect their susceptibility to AMF. To test whether GR24 affects AMF colonization in our experimental system, we added GR24 to the strigolactone-deficient pea ccd8 mutant. Application of GR24 increased AMF colonization in the pea mutant to a similar level as in the pea wild type with normal strigolactone levels, showing clearly that in our experimental setup, application of the GR24 positively affects AMF colonization in strigolactone-deficient plants. Observation of cleared roots after application of GR24 to four AM nonhost plant species inoculated with the AMF Glomus intraradices showed that colonization did not occur.


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