scholarly journals Species-Specific Interactions of Bacillus Innocula and Arbuscular Mycorrhizal Fungi Symbiosis with Winter Wheat

2020 ◽  
Vol 8 (11) ◽  
pp. 1795
Author(s):  
Thomas I. Wilkes ◽  
Douglas J. Warner ◽  
Veronica Edmonds-Brown ◽  
Keith G. Davies
Keyword(s):  
Bacillus Subtilis ◽  
Winter Wheat ◽  
Host Plant ◽  
Root Length ◽  
Vascular Plant ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Fungal Symbiosis ◽  
Species Specific

Arbuscular mycorrhizal (AM) fungi establish close interactions with host plants, an estimated 80% of vascular plant species. The host plant receives additional soil bound nutrients that would otherwise not be available. Other components of the microbiome, such as rhizobacteria, may influence interactions between AM fungi and the host plant. Within a commercial arable crop selected rhizobacteria in combination with AM fungi may benefit crop yields. The precise nature of interactions between rhizobacteria and AM fungi in a symbiotic relationship overall requires greater understanding. The present study aims to assess this relationship by quantifying: (1) AM fungal intracellular root structures (arbuscules) and soil glomalin as an indicator of AM fungal growth; and (2) root length and tiller number as a measure of crop growth, in response to inoculation with one of three species of Bacillus: B. amyloliquefaciences, B. pumilis, or B. subtilis. The influence of soil management, conventional (CT) or zero tillage (ZT) was a further variable evaluated. A significant (p < 0.0001) species-specific impact on the number of quantifiable AM fungal arbuscules was observed. The inoculation of winter wheat (Triticum aestivum) with B. amyloliquefaciences had a positive impact on AM fungal symbiosis, as indicated by an average of 3226 arbuscules per centimetre of root tissue. Bacillus subtilis increased root length significantly (p < 0.01) but decreased fungal symbiosis (p < 0.01). The inoculation of field soils altered the concentration of glomalin, an indicator of AM fungal growth, significantly (p < 0.00001) for each tillage treatment. The greatest increase was associated with B. amyloliquefaciences for both CT (p < 0.0001) and ZT (p < 0.00001). Bacillus subtilis reduced measured glomalin significantly in both tillage treatments (p < 0.0001 and p < 0.00001 for CT and ZT respectively). The interaction between rhizobacteria and AM fungi is variable, being beneficial or detrimental depending on species. This relationship was evident in both tillage treatments and has important implications for maximizing symbiosis in the crop plant-microbiome present in agricultural systems.

scholarly journals Target of rapamycin, PvTOR, is a key regulator of arbuscule development during mycorrhizal symbiosis in Phaseolus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Manoj-Kumar Arthikala ◽  
Kalpana Nanjareddy ◽  
Lourdes Blanco ◽  
Xóchitl Alvarado-Affantranger ◽  
Miguel Lara
Keyword(s):  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Target Of Rapamycin ◽  
Mycorrhizal Symbiosis ◽  
Energy Status ◽  
Symbiotic Associations ◽  
Expression Of Genes ◽  
Fungal Symbiosis ◽  
Am Fungus ◽  
Am Symbiosis

AbstractTarget of rapamycin (TOR) is a conserved central growth regulator in eukaryotes that has a key role in maintaining cellular nutrient and energy status. Arbuscular mycorrhizal (AM) fungi are mutualistic symbionts that assist the plant in increasing nutrient absorption from the rhizosphere. However, the role of legume TOR in AM fungal symbiosis development has not been investigated. In this study, we examined the function of legume TOR in the development and formation of AM fungal symbiosis. RNA-interference-mediated knockdown of TOR transcripts in common bean (Phaseolus vulgaris) hairy roots notably suppressed AM fungus-induced lateral root formation by altering the expression of root meristem regulatory genes, i.e., UPB1, RGFs, and sulfur assimilation and S-phase genes. Mycorrhized PvTOR-knockdown roots had significantly more extraradical hyphae and hyphopodia than the control (empty vector) roots. Strong promoter activity of PvTOR was observed at the site of hyphal penetration and colonization. Colonization along the root length was affected in mycorrhized PvTOR-knockdown roots and the arbuscules were stunted. Furthermore, the expression of genes induced by AM symbiosis such as SWEET1, VPY, VAMP713, and STR was repressed under mycorrhized conditions in PvTOR-knockdown roots. Based on these observations, we conclude that PvTOR is a key player in regulating arbuscule development during AM symbiosis in P. vulgaris. These results provide insight into legume TOR as a potential regulatory factor influencing the symbiotic associations of P. vulgaris and other legumes.

scholarly journals Myristate can be used as a carbon and energy source for the asymbiotic growth of arbuscular mycorrhizal fungi

2019 ◽  
Author(s):  
Yuta Sugiura ◽  
Rei Akiyama ◽  
Sachiko Tanaka ◽  
Koji Yano ◽  
Hiromu Kameoka ◽  
...  
Keyword(s):  
Energy Source ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Mycorrhizal Fungi ◽  
Unsaturated Fatty Acids ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Land Plants ◽  
Symbiotic Associations

AbstractArbuscular mycorrhizal (AM) fungi, forming symbiotic associations with land plants, are obligate symbionts that cannot complete their natural life cycle without a host. Recently, fatty acid auxotrophy of AM fungi is supported by studies showing that lipids synthesized by the host plants are transferred to the fungi and that the latter lack genes encoding cytosolic fatty acid synthases (1-7). Therefore, to establish an asymbiotic cultivation system for AM fungi, we tried to identify the fatty acids that could promote biomass production. To determine whether AM fungi can grow on medium supplied with fatty acids or lipids under asymbiotic conditions, we tested eight saturated or unsaturated fatty acids (C12–C18) and two β-monoacylglycerols. Only myristate (C14:0) led to an increase in biomass of Rhizophagus irregularis, inducing extensive hyphal growth and formation of infection-competent secondary spores. However, such spores were smaller than those generated symbiotically. Furthermore, we demonstrated that R. irregularis can take up fatty acids in its branched hyphae and use myristate as a carbon and energy source. Myristate also promoted the growth of Rhizophagus clarus and Gigaspora margarita. Finally, mixtures of myristate and palmitate accelerated fungal growth and induced a substantial change in fatty acid composition of triacylglycerol compared with single myristate application, although palmitate was not used as a carbon source for cell wall biosynthesis in this culture system. In conclusion, here we demonstrate that myristate boosts asymbiotic growth of AM fungi and can also serve as a carbon and energy source.Significance statementThe origins of arbuscular mycorrhizal (AM) fungi, which form symbiotic associations with land plants, date back over 460 million years ago. During evolution, these fungi acquired an obligate symbiotic lifestyle, and thus depend on their host for essential nutrients. In particular, fatty acids are regarded as crucial nutrients for the survival of AM fungi owing to the absence of genes involved in de novo fatty acid biosynthesis in the AM fungal genomes that have been sequenced so far. Here, we show that myristate initiates AM fungal growth under asymbiotic conditions. These findings will advance pure culture of AM fungi.

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 Tillage, Glyphosate and Beneficial Arbuscular Mycorrhizal Fungi: Optimising Crop Management for Plant–Fungal Symbiosis

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 520 ◽  
Author(s):  
Thomas I. Wilkes ◽  
Douglas J. Warner ◽  
Keith G. Davies ◽  
Veronica Edmonds-Brown
Keyword(s):  
Mycorrhizal Fungi ◽  
Fungal Biomass ◽  
Negative Impact ◽  
Cropping Systems ◽  
Fungal Growth ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Soil Microbiome ◽  
Epsp Synthase ◽  
The Impact

Zero till cropping systems typically apply broad-spectrum herbicides such as glyphosate as an alternative weed control strategy to the physical inversion of the soil provided by cultivation. Glyphosate targets 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase in plants. There is growing evidence that this may have a detrimental impact on non-target organisms such as those present in the soil microbiome. Species of commercial importance, such as arbuscular mycorrhizal (AM) fungi that form a symbiotic relationship with plant roots are an important example. This study investigates the impact of soil cultivation and glyphosate application associated with conventional tillage (CT) and zero tillage (ZT) respectively on AM fungi populations under field and glasshouse conditions. Topsoil (<10 cm) was extracted from CT and ZT fields cropped with winter wheat, plus non-cropped control plots within the same field boundary, throughout the cropping year. Glyphosate was applied in glasshouse experiments at rates between 0 and 350 g L−1. Ergosterol, an indicator of fungal biomass, was measured using high performance liquid chromatography before and after glyphosate application. Fungal root arbuscules, an indicator of AM fungi–root symbiosis, were quantified from the roots of wheat plants. Under glasshouse conditions root arbuscules were consistently higher in wheat grown in ZT field extracted soils (P = 0.01) compared to CT. Glyphosate application however inhibited fungal biomass in both the ZT (P < 0.00001) and CT (P < 0.001) treatments. In the absence of glyphosate, the number of stained root arbuscules increased significantly. Ergosterol levels, used as a proxy for fungal biomass, remained lower in the soil post glyphosate application. The results suggest that CT has a greater negative impact on AM fungal growth than ZT and glyphosate, but that glyphosate is also detrimental to AM fungal growth and hinders subsequent population recovery.

scholarly journals Response of Arbuscular Mycorrhizal Fungi to Hydrologic Gradients in the Rhizosphere ofPhragmites australis(Cav.) Trin ex. Steudel Growing in the Sun Island Wetland

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Li Wang ◽  
Jieting Wu ◽  
Fang Ma ◽  
Jixian Yang ◽  
Shiyang Li ◽  
...  
Keyword(s):  
Host Plant ◽  
Mycorrhizal Fungi ◽  
Plant Biomass ◽  
Growth Parameters ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
The Sun ◽  
Vegetative Period ◽  
Hydrologic Gradients ◽  
Mycorrhizal Association

Within the rhizosphere, AM fungi are a sensitive variable to changes of botanic and environmental conditions, and they may interact with the biomass of plant and other microbes. During the vegetative period of thePhragmites australisgrowing in the Sun Island Wetland (SIW), the variations of AM fungi colonization were studied. Root samples of three hydrologic gradients generally showed AM fungi colonization, suggesting that AM fungi have the ability for adaptation to flooded habitats. There were direct and indirect hydrological related effects with respect to AM fungi biomass, which interacted simultaneously in the rhizosphere. Though water content in soil and reed growth parameters were both positively associated with AM fungi colonization, only the positive correlations between reed biomass parameters and the colonization could be expected, or both the host plant biomass and the AM fungi could be beneficial. The variations in response of host plant to the edaphic and hydrologic conditions may influence the effectiveness of the plant-mycorrhizal association. This study included a hydrologic component to better assess the role and distribution of AM fungi in wetland ecosystems. And because of that, the range of AM fungi was extended, since they actually showed a notable adaptability to hydrologic gradients.

scholarly journals Optimasi simbiosis cendawan mikoriza arbuskula Acaulospora tuberculata dan Gigaspora margarita pada bibit kelapa sawit di tanah masam Optimizing arbuscular mycorrhizal fungi symbiosis Acaulospora tuberculata and Gigaspora margarita with oil palm seedling in acid soil)

2016 ◽  
Vol 70 (2) ◽  
Author(s):  
Happy WIDIASTUTI ◽  
Edi GUHARDJA ◽  
Nampiah SOEKARNO ◽  
L K DARUSMAN ◽  
Didiek Hadjar GOENADI ◽  
...  
Keyword(s):  
Oil Palm ◽  
Mycorrhizal Fungi ◽  
Acid Soil ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
P Uptake ◽  
Fungal Species ◽  
Gigaspora Margarita ◽  
Fertilizer Rate ◽  
Fungal Symbiosis

SummaryAM fungal symbiosis increase the uptake of P in oil palm seedlings. However the optimum condition of symbiosis has to be determined to get higher benefit of AM fungal symbiosis. Optimization of the symbiosis Acaulospora tuberculata and Gigaspora margarita with oil palm seedling in acid soil was determined. An experiment was conducted in polybag sized 40 x 60 cm contained sterilized Cikopomayak soil. Three factors studied were AM fungal species (A. tuberculata, G. margarita), inoculant dose (0.0; 12.5; 25.0; and 37.5% w/w), and fertilizer rate (0; 25; 50; and 100% recommended dose) and each treatment replicated three times. The result showed that optimum growth reached on the inoculant addition of 36% (w/w) in the form of infected roots, hypha, and spores and fertilizer dose of 25% for A. tuberculata, while for G. margarita was 40% (w/w) inoculant and 26% fertilizer. Efectivity of fertilizer and P uptake of oil palm seedling were significantly increased with AM fungi inoculation. P uptake of oil palm seedling inoculated with A. tuberculata increase. RingkasanSimbiosis cendawan mikoriza arbuskula (CMA) dapat meningkatkan serapan P pada pembibitan kelapa sawit. Namun, untuk mendapatkan keuntungan simbiosis yang tinggi perlu diketahui kondisi optimum simbiosis. Simbiosis CMA dengan tanaman sangat dipengaruhi tingkat hara dan dosis inokulum. Percobaan dilakukan dalam polibag berukuran 40 x 60 cm berisi tanah Cikopomayak steril. Tiga faktor yang diuji ialah spesies CMA (A. tuberculata, G. margarita), dosis inokulum campuran (0,0; 12,5; 25,0; dan 37,5% b/b), dosis pupuk (0; 25; 50; dan 100% dosis rekomendasi) dan masing masing perlakuan diulang tiga kali. Hasil percobaan menunjukkan bahwa pertumbuhan optimum dicapai pada pemberian inokulum berupa akar terinfeksi, hifa, dan spora 36% (b/b) dan pupuk 25% untuk A. tuberculata, sedangkan untuk G. margarita ialah 40% (b/b) inokulum dan pupuk 26%. Keefektifan pupuk dan serapan P meningkat secara nyata dengan inokulasi CMA

scholarly journals Molecular genetic identification of arbuscular mycorrhizal fungi

2018 ◽  
Vol 16 (2) ◽  
pp. 11-23 ◽  
Author(s):  
Andrey P. Yurkov ◽  
Alexey A. Kryukov ◽  
Anastasia O. Gorbunova ◽  
Andrey P. Kojemyakov ◽  
Galina V. Stepanova ◽  
...  
Keyword(s):  
Mycorrhizal Fungi ◽  
Molecular Genetic ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Genetic Identification ◽  
Specific Marker ◽  
Selection Of Species ◽  
Species Specific ◽  
Molecular Genetic Identification ◽  
Selection Of

Arbuscular mycorrhiza (AM) is a widespread symbiosis formed by most land plants with fungi from Glomeromycotina subdivision. The main problem in study of AM fungi is the complication in identification, associated with high intra- and interspecific genetic polymorphism, as well as obligate status of AM fungi in relation to host plant. The methodology for AM fungi identification is constantly undergoing major changes. In the review the selection of optimal methods of molecular genetic identification for AM fungi is carried out. The sample preparation, selection of species-specific marker DNA fragments and primers design, amplification including nested PCR are considered. The prospects for cloning and next generation sequencing for AM fungi identification are analyzed and substantiated.

scholarly journals Effect of water stress and AM fungi on the growth performance of pea

2020 ◽  
Vol 4 (1) ◽  
pp. 36-43
Author(s):  
Jaya Thakur ◽  
Bharat Shinde
Keyword(s):  
Water Stress ◽  
Drought Stress ◽  
Root Length ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Dry Weight ◽  
High Water ◽  
Fresh Weight ◽  
Number Of Leaves ◽  
Mycorrhizal Plants

The study was conducted to determine the effect of arbuscular mycorrhizal (AM) fungi inoculation on growth of pea grown under water stressed pot culture conditions. Water stress was given to the pea plants after 30 days at the interval of 4, 8 and 12 days. The data was collected at an interval of 15 days. Three replicates of each set were maintained. . The mixture of AM fungi used for current experiment included the species of Acaulospora denticulata, A. gerdemannii, Glomus macrocarpum, G. maculosum, G. fasciculatum and Scutellospora minuta. The mycorrhizal plants have shown more shoot and root length as compared to the control plants. The height of shoot and root was significantly decreased with the increase in drought stress. Mycorrhizal plants with low water stress showed enhanced shoot and root length than high water stress. The mycorrhizal plants have shown more number of leaves than control plants during drought stress. The number of leaves significantly reduced with the increase in drought stress. The leaves produced by the control plants were comparatively smaller than those of mycorrhizal plants. The dry weight of root and shoot of both control and mycorrhizal plants decreased with the increase in water stress. Mycorrhizal plants showed more dry weight of shoot and root as compared to control plants.  Plants inoculated with AM fungi produce more dry weight than the control plants. The fresh weight of both control and mycorrhizal plants has been decreased with the increase in water stress interval and also the fresh weight of root and shoot was observed higher in mycorrhizal plants as compared to those of control plants.

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