Strigolactones: a cry for help in the rhizosphere

Botany ◽  
2011 ◽  
Vol 89 (8) ◽  
pp. 513-522 ◽  
Author(s):  
Juan A. López-Ráez ◽  
María J. Pozo ◽  
José M. García-Garrido
Keyword(s):  
Host Plant ◽  
Control Strategies ◽  
Arbuscular Mycorrhizal ◽  
Terrestrial Plants ◽  
Crop Species ◽  
Signalling Molecules ◽  
Fungal Partner ◽  
Cry For Help ◽  
Am Symbiosis

Arbuscular mycorrhizal (AM) symbiosis is a beneficial symbiosis established between fungi of the phylum Glomeromycota and over 80% of terrestrial plants, including most agricultural and horticultural crop species. AM symbiosis improves the nutritional status and fitness of the host plant and enables the plant to perform better under stressful conditions. As a result, when plants are growing under unfavourable conditions, they try to recruit their AM fungal partner in the soil. Symbiosis establishment requires a complex chemical dialogue between the two partners, in which signalling molecules such as the strigolactones play a key role. Under deficient nutrient conditions, the host plant increases the production of strigolactones to promote fungal development and symbiosis establishment (a “cry for help”). As a clue to host presence in the rhizosphere, strigolactones are also detected by other organisms, particularly root parasitic plants, and therefore promote a parasitic interaction. We review here the role of strigolactones and their interaction with other phytohormones during AM symbiosis, paying special attention to the implications of the chemical communication that takes place in the rhizosphere. Finally, we point out the potential use of this molecular dialogue as a target for developing new biological control strategies against deleterious organisms such as root parasitic weeds.

scholarly journals The effect of inoculation with arbuscular mycorrhizal fungus Rhizophagus irregularis on cytokinin content in a highly mycotrophic Medicago lupulina line under low phosphorus level in the soil

2017 ◽  
Vol 63 (No. 11) ◽  
pp. 519-524 ◽  
Author(s):  
Yurkov Andrey ◽  
Veselova Svetlana ◽  
Jacobi Lidia ◽  
Stepanova Galina ◽  
Yemelyanov Vladislav ◽  
...  
Keyword(s):  
Phosphorus Deficiency ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Zeatin Riboside ◽  
Rhizophagus Irregularis ◽  
Medicago Lupulina ◽  
Hormone Balance ◽  
Low Phosphorus ◽  
Am Symbiosis

The study is focused on the elucidation of the role of cytokinins (CKs, zeatin and zeatin riboside) in the development of effective arbuscular mycorrhiza (AM) symbiosis with Medicago lupulina. An important mechanism involved in the regulation of host plant growth is supposed to be linked to the modulation of plant hormone balance. The data obtained revealed the formation of an effective AM-symbiosis (M. lupulina + Rhizophagus irregularis) under phosphorus-deficiency. At the shooting stage (35<sup>th</sup> day after sowing), it is characterized by a decrease in the root:shoot ratio, the lowering in arbuscules and vesicle abundances, but an increase in the intensity of mycelium development. Mycorrhized plants differed from the control ones by higher CK levels in both roots and leaves. Zeatin and zeatin riboside concentration exhibited uneven alterations over time. A role of mycelium in the modulation of CK balance has been discussed.

scholarly journals MycoRed: Betalain pigments enable in vivo real-time visualisation of arbuscular mycorrhizal colonisation

PLoS Biology ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. e3001326
Author(s):  
Alfonso Timoneda ◽  
Temur Yunusov ◽  
Clement Quan ◽  
Aleksandr Gavrin ◽  
Samuel F. Brockington ◽  
...  
Keyword(s):  
Crop Yields ◽  
Arbuscular Mycorrhizal ◽  
Crop Species ◽  
Fungal Colonisation ◽  
Visual Markers ◽  
Mycorrhizal Colonisation ◽  
Am Symbiosis ◽  
Colonisation Dynamics ◽  
Root Tissues

Arbuscular mycorrhiza (AM) are mutualistic interactions formed between soil fungi and plant roots. AM symbiosis is a fundamental and widespread trait in plants with the potential to sustainably enhance future crop yields. However, improving AM fungal association in crop species requires a fundamental understanding of host colonisation dynamics across varying agronomic and ecological contexts. To this end, we demonstrate the use of betalain pigments as in vivo visual markers for the occurrence and distribution of AM fungal colonisation by Rhizophagus irregularis in Medicago truncatula and Nicotiana benthamiana roots. Using established and novel AM-responsive promoters, we assembled multigene reporter constructs that enable the AM-controlled expression of the core betalain synthesis genes. We show that betalain colouration is specifically induced in root tissues and cells where fungal colonisation has occurred. In a rhizotron setup, we also demonstrate that betalain staining allows for the noninvasive tracing of fungal colonisation along the root system over time. We present MycoRed, a useful innovative method that will expand and complement currently used fungal visualisation techniques to advance knowledge in the field of AM symbiosis.

scholarly journals Phytohormones Regulate the Development of Arbuscular Mycorrhizal Symbiosis

2018 ◽  
Vol 19 (10) ◽  
pp. 3146 ◽  
Author(s):  
Dehua Liao ◽  
Shuangshuang Wang ◽  
Miaomiao Cui ◽  
Jinhui Liu ◽  
Aiqun Chen ◽  
...  
Keyword(s):  
Early Recognition ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Symbiosis ◽  
Dependent Manner ◽  
Terrestrial Plants ◽  
Root Cells ◽  
Della Proteins ◽  
Am Symbiosis

Most terrestrial plants are able to form a root symbiosis with arbuscular mycorrhizal (AM) fungi for enhancing the assimilation of mineral nutrients. AM fungi are obligate symbionts that depend on host plants as their sole carbon source. Development of an AM association requires a continuous signal exchange between the two symbionts, which triggers coordinated differentiation of both partners, to enable their interaction within the root cells. The control of the AM symbiosis involves a finely-tuned process, and an increasing number of studies have pointed to a pivotal role of several phytohormones, such as strigolactones (SLs), gibberellic acids (GAs), and auxin, in the modulation of AM symbiosis, through the early recognition of events up to the final arbuscular formation. SLs are involved in the presymbiotic growth of the fungus, while auxin is required for both the early steps of fungal growth and the differentiation of arbuscules. GAs modulate arbuscule formation in a dose-dependent manner, via DELLA proteins, a group of GRAS transcription factors that negatively control the GA signaling. Here, we summarize the recent findings on the roles of these plant hormones in AM symbiosis, and also explore the current understanding of how the DELLA proteins act as central regulators to coordinate plant hormone signaling, to regulate the AM symbiosis.

Novel Insights into Host Receptors and Receptor-mediated Signaling that Regulate Arbuscular Mycorrhizal Symbiosis

2020 ◽  
Author(s):  
Fahad Nasir ◽  
Ali Bahadur ◽  
Xiaolong Lin ◽  
Yingzhi Gao ◽  
Chunjie Tian
Keyword(s):  
Host Plant ◽  
Host Plants ◽  
Agronomic Traits ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Land Plant ◽  
Physical Contact ◽  
Mycorrhizal Symbiosis ◽  
Downstream Signaling ◽  
Am Symbiosis

Abstract More than 80% of land plant species benefit from symbiotic partnerships with arbuscular mycorrhizal (AM) fungi that assist in nutrient acquisition and enhance the ability of host plants to adapt to environmental constraints. Host-generated plasma membrane-residing receptor-like kinases and the α/β-hydrolases, e.g. DWARF14-LIKE (D14L), a putative karrikin receptor, are used to detect the presence of AM fungi prior to physical contact between the host and fungus. Detection induces the activation of symbiosis-related transcriptional programming, enabling the successful establishment of AM symbiosis. In order to prevent hyper-colonization and to maintain a mutually beneficial association, the host plants precisely monitor and control AM symbiosis during the post-symbiotic stage via different molecular strategies. While previous studies have elucidated how host plant receptors and receptor-mediated signaling regulate AM symbiosis, the molecular details underlying these processes remain poorly understood. The recent identification of a rice (Oryza sativa) CHITIN-ELICITOR RECEPTOR-KINASE 1 (OsCERK1) interaction partner MYC FACTOR RECEPTOR 1 (OsMYR1), as well as new insights into D14L-receptor- and SUPER NUMERIC NODULES 1 (SUNN1) receptor-mediated signaling have improved our understanding of how host plant receptors and their corresponding signaling regulate AM symbiosis. The present review summarizes these and other current findings that have increased our limited understanding of receptor-mediated signaling mechanisms involved in the regulation of AM symbiosis. The identified receptors and/or their downstream signaling components could potentially be used to engineer economically-important crops with improved agronomic traits by conferring the ability to control the colonization of AM fungi in a precise manner.

scholarly journals Expression Pattern Suggests a Role of MiR399 in the Regulation of the Cellular Response to Local Pi Increase During Arbuscular Mycorrhizal Symbiosis

2010 ◽  
Vol 23 (7) ◽  
pp. 915-926 ◽  
Author(s):  
Anja Branscheid ◽  
Daniela Sieh ◽  
Bikram Datt Pant ◽  
Patrick May ◽  
Emanuel A. Devers ◽  
...  
Keyword(s):  
Cellular Response ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Mycorrhizal Symbiosis ◽  
Pi Homeostasis ◽  
Pi Starvation ◽  
Mycorrhizal Roots ◽  
Am Symbiosis ◽  
Pi Stress

Many plants improve their phosphate (Pi) availability by forming mutualistic associations with arbuscular mycorrhizal (AM) fungi. Pi-repleted plants are much less colonized by AM fungi than Pi-depleted plants. This indicates a link between plant Pi signaling and AM development. MicroRNAs (miR) of the 399 family are systemic Pi-starvation signals important for maintenance of Pi homeostasis in Arabidopsis thaliana and might also qualify as signals regulating AM development in response to Pi availability. MiR399 could either represent the systemic low-Pi signal promoting or required for AM formation or they could act as counter players of systemic Pi-availability signals that suppress AM symbiosis. To test either of these assumptions, we analyzed the miR399 family in the AM-capable plant model Medicago truncatula and could experimentally confirm 10 novel MIR399 genes in this species. Pi-depleted plants showed increased expression of mature miR399 and multiple pri-miR399, and unexpectedly, levels of five of the 15 pri-miR399 species were higher in leaves of mycorrhizal plants than in leaves of nonmycorrhizal plants. Compared with nonmycorrhizal Pi-depleted roots, mycorrhizal roots of Pi-depleted M. truncatula and tobacco plants had increased Pi contents due to symbiotic Pi uptake but displayed higher mature miR399 levels. Expression levels of MtPho2 remained low and PHO2-dependent Pi-stress marker transcript levels remained high in these mycorrhizal roots. Hence, an AM symbiosis-related signal appears to increase miR399 expression and decrease PHO2 activity. MiR399 overexpression in tobacco suggested that miR399 alone is not sufficient to improve mycorrhizal colonization supporting the assumption that, in mycorrhizal roots, increased miR399 are necessary to keep the MtPho2 expression and activity low, which would otherwise increase in response to symbiotic Pi uptake.

scholarly journals Strigolactones as mediators between fungi and plants

2018 ◽  
Vol 53 (2) ◽  
Author(s):  
Anita Kowalczyk ◽  
Katarzyna Hrynkiewicz
Keyword(s):  
Host Plant ◽  
Plant Architecture ◽  
Plant Protection ◽  
Arbuscular Mycorrhizal ◽  
Plant Protection Products ◽  
Mycorrhizal Symbiosis ◽  
Terrestrial Plants ◽  
Way Of Life ◽  
Genes Encoding ◽  
Arbuscular Mycorrhizal Fungal

A constantly changing environment is challenging for all organisms on Earth, especially for terrestrial plants, which face several environmental stresses despite their static way of life. In attempts to understand the mechanisms responsible for plant growth and development, scientists have recently focused on a small group of carotenoid derivatives called “strigolactones” (SLs), which are synthesized mostly in the roots in response to a variety of external factors. Strigolactones are compounds that define plant plasticity towards many environmental factors, including the establishment of mycorrhizal symbiosis under nutrient-deficient conditions. As exogenous signals, they can stimulate the branching of arbuscular mycorrhizal fungal (AMF) hyphae and as endogenous signals they adjust a plant architecture, including changes within the roots, allowing host plant and fungi to meet. SLs can also function as signaling molecules that allow colonization and establishment of the later stages of mutualistic symbioses between organisms such as AMF. SLs act on AMF metabolism by stimulating its mitochondrial respiration. Genes encoding enzymes crucial for SL biosynthesis – <em>CCD7</em> and <em>CCD8</em> – are also found in gymnosperm genomes, which encourages speculation that strigolactones may also be part of a host-plant and ectomycorrhizal fungi signaling pathway during the establishment of symbiosis. Nevertheless, SLs impact on ectomycorrhiza formation remain unknown. The broad spectrum of SL bioactivity has made these compounds valuable from an industrial perspective. In the future, SLs may be commercialized in plant protection products, biostimulants, or as substances used in genetic engineering to allow the creation of crops capable of growing under disadvantageous conditions.

scholarly journals Role of arbuscular mycorrhizal fungi (AMF) in global sustainable development

2011 ◽  
Vol 3 (2) ◽  
pp. 340-351 ◽  
Author(s):  
Ashok Aggarwal ◽  
Nisha Kadian ◽  
Anju Tanwar ◽  
Alpa Yadav ◽  
K. K. Gupta
Keyword(s):  
Sustainable Development ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Mycorrhizal Symbiosis ◽  
Terrestrial Plants ◽  
Host Root ◽  
Vesicular Arbuscular ◽  
Highly Evolved

Mycorrhizal symbiosis is a highly evolved mutually beneficial relationship that exists between Arbuscular Mycorrhizal Fungi (AMF) and most of the vascular plants. The majority of the terrestrial plants form association with Vesicular Arbuscular Mycorrhiza (VAM) or Arbuscular Mycorrhizal fungi (AMF). This symbiosis confers benefits directly to the host plant’s growth and development through the acquisition of Phosphorus (P) and other mineral nutrients from the soil by the AMF. In addition, their function ranges from stress alleviation to bioremediation in soils polluted with heavy metals. They may also enhance the protection of plants against pathogens and increases the plant diversity. This is achieved by the growth of AMF mycelium within the host root (intra radical) and out into the soil (extra radical) beyond. Proper management of Arbuscular Mycorrhizal fungi has the potential to improve the profitability and sustainability of agricultural systems. In this review article, the discussion is restricted to the mycorrhizal benefits and their role in sustainable development.

Arbuscular Mycorrhizal symbiosis enhances aggregate formation and organic matter sequestration in alkaline Fe ore tailings

2021 ◽  
Author(s):  
Zhen Li ◽  
Songlin Wu ◽  
Longbin Huang
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Aggregate Formation ◽  
Organic C ◽  
Mineral Particles ◽  
Am Symbiosis ◽  
C And N

&lt;p&gt;Alkaline Fe ore tailings are by far one of the most challenging environmental issue facing the global mining industry, which is ranked 4&lt;sup&gt;th&lt;/sup&gt; globally in terms of their discharge volumes in storage dams. These tailings possess poor physical structures and adverse chemical properties (e.g., alkaline pH and deficiencies of organic carbon and nutrients) and it is hard for sustainable colonization of plants and microbial communities. Eco-engineering tailings into soil-like substrate in situ is a promising technology to achieve sustainable rehabilitation of tailing landscape. The formation of water stable aggregates (WSA) in tailings primed with eco-engineering inpiuts (e.g., plant biomass organic matter and fertilisers) is indicative of the first milestone of soil formaiton, resulting from bio-geochemically driven mineral weathering and cementation. WSAs are basic physical units underpinning soil structure and functions, such as the porosity and hydraulic conductivity, gas exchange and water retention, biological activities of microbes and roots. The further development and evolution may be enhanced by Arbuscular mycorrhizal (AM) fungi associated with plants colonising infertile soil (such as tailing-soil), because of their role in generating organic cements and organo-mineral interactions. Our previous study found that AM fungi were present in the Fe ore mine tailing site, associated with colonising native plants. In the present study, we have investigated the role of AM symbiosis (Glomus spp. in association with Sorghum spp.) in aggregate formation and organic matter sequestration in Fe ore tailings eco-engineered with organic matter amendment and pioneer plant colonization. The results showed that AM fungi formed symbiotic association with Sorghum spp. plant roots (with mycorrhizal colonization intensity above 80%) in the eco-engineered tailings. Quantitatively, AM symbiosis enhanced the formation of micro-aggregates (53~250 um) rather than macro-aggregate aggregates (250 um~2000 um) formation, which may be partially due to the direct role of extra-radical mycelium as revealed by FE-SEM analysis. Qualitatively, AM symbiosis increased the amount of organic carbon and nitrogen associated with mineral particles in the macro-aggregates. Those organic carbon associated with minerals was found to be rich in carboxyl C and alkyl C, as revealed by synchrotron based C 1s X-ray absorption near edge structure (NEXAFS, conducted in Australia Synchrotron) and the Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra. Overall, the study revealed the role of AM fungi in advancing the formation of microaggregates and increasing the sequestration of organic C and N in macroaggregates in the eco-engineered Fe ore tailings. These suggest that AM fungi inoculum be added to pioneer plants to not only enhance plant growth via improved nutrient and water acquisition, but also to advance aggregate formation and quality via increased organic C and N sequestration with impacted mineral particles.&lt;/p&gt;

scholarly journals Silencing MdGH3-2/12 in apple reduces drought resistance by regulating AM colonization

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Dong Huang ◽  
Qian Wang ◽  
Zhijun Zhang ◽  
Guangquan Jing ◽  
Mengnan Ma ◽  
...  
Keyword(s):  
Drought Stress ◽  
Mycorrhizal Fungi ◽  
Crop Yields ◽  
Negative Impact ◽  
Arbuscular Mycorrhizal ◽  
Ros Scavenging ◽  
Crop Species ◽  
Relative Water ◽  
Am Symbiosis ◽  
Water Contents

AbstractDrought leads to reductions in plant growth and crop yields. Arbuscular mycorrhizal fungi (AMF), which form symbioses with the roots of the most important crop species, alleviate drought stress in plants. In the present work, we identified 14 GH3 genes in apple (Malus domestica) and provided evidence that MdGH3-2 and MdGH3-12 play important roles during AM symbiosis. The expression of both MdGH3-2 and MdGH3-12 was upregulated during mycorrhization, and the silencing of MdGH3-2/12 had a negative impact on AM colonization. MdGH3-2/12 silencing resulted in the downregulation of five genes involved in strigolactone synthesis, and there was a corresponding change in root strigolactone content. Furthermore, we observed lower root dry weights in RNAi lines under AM inoculation conditions. Mycorrhizal transgenic plants showed greater sensitivity to drought stress than WT, as indicated by their higher relative electrolytic leakage and lower relative water contents, osmotic adjustment ability, ROS scavenging ability, photosynthetic capacity, chlorophyll fluorescence values, and abscisic acid contents. Taken together, these data demonstrate that MdGH3-2/12 plays an important role in AM symbiosis and drought stress tolerance in apple.

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