Extraction of short chain chitooligosaccharides from fungal biomass and their use as promoters of arbuscular mycorrhizal symbiosis

AbstractShort chain chitooligosaccharides (COs) are chitin derivative molecules involved in plant-fungus signaling during arbuscular mycorrhizal (AM) interactions. In host plants, COs activate a symbiotic signalling pathway that regulates AM-related gene expression. Furthermore, exogenous CO application was shown to promote AM establishment, with a major interest for agricultural applications of AM fungi as biofertilizers. Currently, the main source of commercial COs is from the shrimp processing industry, but purification costs and environmental concerns limit the convenience of this approach. In an attempt to find a low cost and low impact alternative, this work aimed to isolate, characterize and test the bioactivity of COs from selected strains of phylogenetically distant filamentous fungi: Pleurotus ostreatus, Cunninghamella bertholletiae and Trichoderma viride. Our optimized protocol successfully isolated short chain COs from lyophilized fungal biomass. Fungal COs were more acetylated and displayed a higher biological activity compared to shrimp-derived COs, a feature that—alongside low production costs—opens promising perspectives for the large scale use of COs in agriculture.

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Arbuscular mycorrhizal symbiosis facilitates apricot seedling (Prunus sibirica L.) growth and photosynthesis in northwest China

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00408-6 ◽

2021 ◽

Author(s):

Yinli Bi ◽

Linlin Xie ◽

Zhigang Wang ◽

Kun Wang ◽

Wenwen Liu ◽

...

Keyword(s):

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Northwest China ◽

Shaanxi Province ◽

Mycorrhizal Symbiosis ◽

Seedling Physiology ◽

Grassland Ecosystems ◽

Time Period ◽

Seedling Biomass ◽

Experimental Treatments

AbstractArbuscular mycorrhizal (AM) fungi can successfully enhance photosynthesis (Pn) and plants growth in agricultural or grassland ecosystems. However, how the symbionts affect species restoration in sunlight-intensive areas remains largely unexplored. Therefore, this study’s objective was to assess the effect of AM fungi on apricot seedling physiology, within a specific time period, in northwest China. In 2010, an experimental field was established in Shaanxi Province, northwest China. The experimental treatments included two AM fungi inoculation levels (0 or 100 g of AM fungal inoculum per seedling), three shade levels (1900, 1100, and 550 µmol m−2 s−1), and three ages (1, 3, and 5 years) of transplantation. We examined growth, Pn, and morphological indicators of apricot (Prunus sibirica L.) seedling performances in 2011, 2013, and 2015. The colonization rate in mycorrhizal seedlings with similar amounts of shade is higher than the corresponding controls. The mycorrhizal seedling biomass is significantly higher than the corresponding non-mycorrhizal seedling biomass. Generally, Pn, stomatal conductance (Gs), transpiration rate (Tr), and water use efficiency are also significantly higher in the mycorrhizal seedlings. Moreover, mycorrhizal seedlings with light shade (LS) have the highest Pn. WUE is increased in non-mycorrhizal seedlings because of the reduction in Tr, while Tr is increased in mycorrhizal seedlings with shade. There is a significant increase in the N, P, and K fractions detected in roots compared with shoots. This means that LS had apparent benefits for mycorrhizal seedlings. Our results also indicate that AM fungi, combined with LS, exert a positive effect on apricot behavior.

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

Scientific Reports ◽

10.1038/s41598-021-90288-2 ◽

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.

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Integrating physiological, community, and evolutionary perspectives on the arbuscular mycorrhizal symbiosis

Botany ◽

10.1139/cjb-2013-0182 ◽

2014 ◽

Vol 92 (4) ◽

pp. 241-251 ◽

Cited By ~ 33

Author(s):

Ylva Lekberg ◽

Roger T. Koide

Keyword(s):

Evolutionary Biology ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Partner Choice ◽

Mycorrhizal Symbiosis ◽

Physiological Processes ◽

Resource Transfers ◽

Am Symbiosis ◽

Controlled Environments ◽

Natural Settings

Our knowledge of arbuscular mycorrhizal (AM) function is largely based on results from short-term studies in controlled environments. While these have provided many important insights into the potential effects of the symbiosis on the two symbionts and their communities, they may have also inadvertently led to faulty assumptions about the function of the symbiosis in natural settings. Here we highlight the consequences of failing to consider the AM symbiosis from the perspectives of community ecology and evolutionary biology. Also, we argue that by distinguishing between physiological and evolutionary viewpoints, we may be able to resolve controversies regarding the mutualistic vs. parasitic nature of the symbiosis. Further, while most AM research has emphasized resource transfers, primarily phosphate and carbohydrate, our perceptions of parasitism, cheating, bet-hedging, and partner choice would most likely change if we considered other services. Finally, to gain a fuller understanding of the role of the AM symbiosis in nature, we need to better integrate physiological processes of plants and their AM fungi with their naturally occurring temporal and spatial patterns. It is our hope that this article will generate some fruitful discussions and make a contribution toward this end.

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Dual RNA-seq reveals large-scale non-conserved genotype x genotype specific genetic reprograming and molecular crosstalk in the mycorrhizal symbiosis

10.1101/393637 ◽

2018 ◽

Author(s):

Ivan D. Mateus ◽

Frédéric G. Masclaux ◽

Consolée Aletti ◽

Edward C. Rojas ◽

Romain Savary ◽

...

Keyword(s):

Mycorrhizal Fungi ◽

Large Scale ◽

Molecular Mechanisms ◽

Arbuscular Mycorrhizal ◽

Mycorrhizal Symbiosis ◽

Rna Seq ◽

Plant Host ◽

Transcriptional Responses ◽

Plant Genes ◽

Fungal Genetic

AbstractArbuscular mycorrhizal fungi (AMF) impact plant growth and are a major driver of plant diversity and productivity. We quantified the contribution of intra-specific genetic variability in cassava (Manihot esculenta) and Rhizophagus irregularis to gene reprogramming in symbioses using dual RNA-sequencing. A large number of cassava genes exhibited altered transcriptional responses to the fungus but transcription of most of these plant genes (72%) responded in a different direction or magnitude depending on the plant genotype. Two AMF isolates displayed large differences in their transcription, but the direction and magnitude of the transcriptional responses for a large number of these genes was also strongly influenced by the genotype of the plant host. This indicates that unlike the highly conserved plant genes necessary for the symbiosis establishment, plant and fungal gene transcriptional responses are not conserved and are greatly influenced by plant and fungal genetic differences, even at the within-species level. The transcriptional variability detected allowed us to identify an extensive gene network showing the interplay in plant-fungal reprogramming in the symbiosis. Key genes illustrated that the two organisms jointly program their cytoskeleton organisation during growth of the fungus inside roots. Our study reveals that plant and fungal genetic variation plays a strong role in shaping the genetic reprograming in response to symbiosis, indicating considerable genotype x genotype interactions in the mycorrhizal symbiosis. Such variation needs to be considered in order to understand the molecular mechanisms between AMF and their plant hosts in natural communities.

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Arbuscular mycorrhizal fungi promote the growth of plants in the mining associated clay

Scientific Reports ◽

10.1038/s41598-020-59447-9 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Ziheng Song ◽

Yinli Bi ◽

Jian Zhang ◽

Yunli Gong ◽

Huihui Yang

Keyword(s):

Arbuscular Mycorrhizal Fungi ◽

Mycorrhizal Fungi ◽

Structural Equation ◽

Large Scale ◽

Low Cost ◽

Eastern China ◽

Arbuscular Mycorrhizal ◽

Open Pit ◽

Open Pit Mining ◽

Amf Inoculation

Abstract It is urgent to restore the ecological function in open-pit mining areas on grassland in Eastern China. The open-pit mines have abundant of mining associated clay, which is desirable for using as a soil source for ecological restoration. The mining associated clay in Hulunbuir district, Inner Mongolia was selected and mixed with a sandy soil at a ratio of 1:1 (S_C soil). Also, effects of arbuscular mycorrhizal fungi (AMF) inoculation on soil functions were studied. The aboveground and underground biomass of maize in S_C soil was 1.49 and 2.41 times higher than that of clay soil, respectively. In the topsoil and S_C soil, the growth hormone (IAA) and cytokinin (CTK) levels of maize were higher than that of clay, while abscission acid (ABA) levels were lower. The inoculation with AMF could significantly improve the biomass of maize and enhance the stress resistance of plants. Through structural equation model (SEM) analyses, it was found that the soil type and AMF inoculation had the most direct impact on maize growth and biomass content. These finds extend our knowledge regarding a low-cost method for physical and biological improvement of mining associated clay, and to provide theoretical support for large-scale application in the future.

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Differential Response of Mycorrhizal Plants to Tomato bushy stunt virus and Tomato mosaic virus Infection

Microorganisms ◽

10.3390/microorganisms8122038 ◽

2020 ◽

Vol 8 (12) ◽

pp. 2038

Author(s):

Neda Khoshkhatti ◽

Omid Eini ◽

Davoud Koolivand ◽

Antreas Pogiatzis ◽

John N. Klironomos ◽

...

Keyword(s):

Mosaic Virus ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Tomato Bushy Stunt Virus ◽

Uninfected Control ◽

Tomato Mosaic Virus ◽

Mycorrhizal Symbiosis ◽

Pr Genes ◽

Tomato Plants ◽

Virus Accumulation

Tomato bushy stunt virus (TBSV) and Tomato mosaic virus (ToMV) are important economic pathogens in tomato fields. Rhizoglomus irregulare is a species of arbuscular mycorrhizal (AM) fungus that provides nutrients to host plants. To understand the effect of R. irregulare on the infection by TBSV/ToMV in tomato plants, in a completely randomized design, five treatments, including uninfected control plants without AM fungi (C), uninfected control plants with AM fungi (M) TBSV/ToMV-infected plants without AM fungi (V), TBSV/ToMV-infected plants before mycorrhiza (VM) inoculation, and inoculated plants with mycorrhiza before TBSV/ToMV infection (MV), were studied. Factors including viral RNA accumulation and expression of Pathogenesis Related proteins (PR) coding genes including PR1, PR2, and PR3 in the young leaves were measured. For TBSV, a lower level of virus accumulation and a higher expression of PR genes in MV plants were observed compared to V and VM plants. In contrast, for ToMV, a higher level of virus accumulation and a lower expression of PR genes in MV plants were observed as compared to V and VM plants. These results indicated that mycorrhizal symbiosis reduces or increases the viral accumulation possibly via the regulation of PR genes in tomato plants.

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Arbuscular Mycorrhizal Symbiosis Affects Plant Immunity to Viral Infection and Accumulation

Viruses ◽

10.3390/v11060534 ◽

2019 ◽

Vol 11 (6) ◽

pp. 534 ◽

Cited By ~ 8

Author(s):

Zhipeng Hao ◽

Wei Xie ◽

Baodong Chen

Keyword(s):

Viral Infection ◽

Plant Immunity ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Plant Viruses ◽

Limiting Factors ◽

Systemic Resistance ◽

Mycorrhizal Symbiosis ◽

Complex Nature ◽

Terrestrial Plants

Arbuscular mycorrhizal (AM) fungi, as root symbionts of most terrestrial plants, improve plant growth and fitness. In addition to the improved plant nutritional status, the physiological changes that trigger metabolic changes in the root via AM fungi can also increase the host ability to overcome biotic and abiotic stresses. Plant viruses are one of the important limiting factors for the commercial cultivation of various crops. The effect of AM fungi on viral infection is variable, and considerable attention is focused on shoot virus infection. This review provides an overview of the potential of AM fungi as bioprotection agents against viral diseases and emphasizes the complex nature of plant–fungus–virus interactions. Several mechanisms, including modulated plant tolerance, manipulation of induced systemic resistance (ISR), and altered vector pressure are involved in such interactions. We propose that using “omics” tools will provide detailed insights into the complex mechanisms underlying mycorrhizal-mediated plant immunity.

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Photosynthetic performance and stevioside concentration are improved by the arbuscular mycorrhizal symbiosis in Stevia rebaudiana under different phosphate concentrations

PeerJ ◽

10.7717/peerj.10173 ◽

2020 ◽

Vol 8 ◽

pp. e10173

Author(s):

Luis G. Sarmiento-López ◽

Melina López-Meyer ◽

Gabriela Sepúlveda-Jiménez ◽

Luis Cárdenas ◽

Mario Rodríguez-Monroy

Keyword(s):

Stevia Rebaudiana ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

P Uptake ◽

Photosynthetic Performance ◽

Phosphate Concentration ◽

Mycorrhizal Symbiosis ◽

Steviol Glycosides ◽

Rebaudioside A ◽

Carotenoid Concentration

In plants, phosphorus (P) uptake occurs via arbuscular mycorrhizal (AM) symbiosis and through plant roots. The phosphate concentration is known to affect colonization by AM fungi, and the effect depends on the plant species. Stevia rebaudiana plants are valuable sources of sweetener compounds called steviol glycosides (SGs), and the principal components of SGs are stevioside and rebaudioside A. However, a detailed analysis describing the effect of the phosphate concentration on the colonization of AM fungi in the roots and the relationship of these factors to the accumulation of SGs and photochemical performance has not been performed; such an analysis was the aim of this study. The results indicated that low phosphate concentrations (20 and 200 µM KH2PO4) induced a high percentage of colonization by Rhizophagus irregularis in the roots of S. rebaudiana, while high phosphate concentrations (500 and 1,000 µM KH2PO4) reduced colonization. The morphology of the colonization structure is a typical Arum-type mycorrhiza, and a mycorrhiza-specific phosphate transporter was identified. Colonization with low phosphate concentrations improved plant growth, chlorophyll and carotenoid concentration, and photochemical performance. The transcription of the genes that encode kaurene oxidase and glucosyltransferase (UGT74G1) was upregulated in colonized plants at 200 µM KH2PO4, which was consistent with the observed patterns of stevioside accumulation. In contrast, at 200 µM KH2PO4, the transcription of UGT76G1 and the accumulation of rebaudioside A were higher in noncolonized plants than in colonized plants. These results indicate that a low phosphate concentration improves mycorrhizal colonization and modulates the stevioside and rebaudioside A concentration by regulating the transcription of the genes that encode kaurene oxidase and glucosyltransferases, which are involved in stevioside and rebaudioside A synthesis in S. rebaudiana.

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Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease

Frontiers in Forests and Global Change ◽

10.3389/ffgc.2020.593243 ◽

2021 ◽

Vol 3 ◽

Author(s):

Sarah J. Sapsford ◽

Trudy Paap ◽

Giles E. St. J. Hardy ◽

Treena I. Burgess

Keyword(s):

Soil Properties ◽

Soil Nutrients ◽

Large Scale ◽

Stand Structure ◽

Disease Incidence ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Illumina Miseq ◽

Fungal Communities ◽

Canker Disease

In forest ecosystems, habitat fragmentation negatively impacts stand structure and biodiversity; the resulting fragmented patches of forest have distinct, disturbed edge habitats that experience different environmental conditions than the interiors of the fragments. In southwest Western Australia, there is a large-scale decline of the keystone tree species Corymbia calophylla following fragmentation and land use change. These changes have altered stand structure and increased their susceptibility to an endemic fungal pathogen, Quambalaria coyrecup, which causes chronic canker disease especially along disturbed forest habitats. However, the impacts of fragmentation on belowground processes in this system are not well-understood. We examined the effects of fragmentation on abiotic soil properties and ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungal communities, and whether these belowground changes were drivers of disease incidence. We collected soil from 17 sites across the distribution range of C. calophylla. Soils were collected across a gradient from disturbed, diseased areas to undisturbed, disease-free areas. We analysed soil nutrients and grew C. calophylla plants as a bioassay host. Plants were harvested and roots collected after 6 months of growth. DNA was extracted from the roots, amplified using fungal specific primers and sequenced using Illumina MiSeq. Concentrations of key soil nutrients such as nitrogen, phosphorus and potassium were much higher along the disturbed, diseased edges in comparison to undisturbed areas. Disturbance altered the community composition of ECM and AM fungi; however, only ECM fungal communities had lower rarefied richness and diversity along the disturbed, diseased areas compared to undisturbed areas. Accounting for effects of disturbance, ECM fungal diversity and leaf litter depth were highly correlated with increased disease incidence in C. calophylla. In the face of global change, increased virulence of an endemic pathogen has emerged in this Mediterranean-type forest.

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Arbuscular Mycorrhizal Assessment of Ornamental Trees Grown in Tennessee Field Soils

HortScience ◽

10.21273/hortsci.37.5.778 ◽

2002 ◽

Vol 37 (5) ◽

pp. 778-782 ◽

Cited By ~ 2

Author(s):

W.E. Klingeman ◽

R.M. Augé ◽

P.C. Flanagan

Keyword(s):

Soil Ph ◽

Acer Rubrum ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Mycorrhizal Symbiosis ◽

Inoculum Potential ◽

Red Maple ◽

Trap Crop ◽

Tissue Samples ◽

Field Soils

Mycorrhizal symbiosis, a natural association between roots and certain soil fungi, can improve growth and increase stress resistance of many nursery crops. Field soils of four middle Tennessee and two eastern Tennessee nurseries were surveyed for their mycorrhizal inoculum potential (MIP), phosphorus (P) and potassium (K) concentrations, and soil pH. Arbuscular mycorrhizal (AM) fungi, which colonized seedlings of a Sorghum bicolor trap-crop, were recovered from all soils. Tissue samples were taken from young roots of three economically important tree species grown in nursery field soils: red maple (Acer rubrum L. `October Glory'), flowering dogwood (Cornus florida L. `Cherokee Princess'), and Kwanzan cherry (Prunus serrulata Lindl. `Kwanzan'). AM fungi, regardless of soil type, soil pH, or P or K concentration, had colonized young roots of all three species. Unless interested in establishing exotic mycorrhizae, ornamental nursery producers in Tennessee do not need to supplement field soils with these beneficial fungi.

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