Addition of high C:N crop residues to a P-limited substrate constrains the benefits of arbuscular mycorrhizal symbiosis for wheat P and N nutrition

AbstractMany aspects concerning the role of arbuscular mycorrhizal (AM) fungi in plant nutrient uptake from organic sources remain unclear. Here, we investigated the contribution of AM symbiosis to N and P uptake by durum wheat after the addition of a high C:N biomass to a P-limited soil. Plants were grown in pots in the presence or absence of a multispecies AM inoculum, with (Org) or without (Ctr) the addition of 15N-labelled organic matter (OM). A further treatment, in which 15N was applied in mineral form (Ctr+N) in the same amount as that supplied in the Org treatment, was also included. Inoculation with AM had positive effects on plant growth in both control treatments (Ctr and Ctr+N), mainly linked to an increase in plant P uptake. The addition of OM, increasing the P available in the soil for the plants, resulted in a marked decrease in the contribution of AM symbiosis to plant growth and nutrient uptake, although the percentage of mycorrhization was higher in the Org treatment than in the controls. In addition, mycorrhization drastically reduced the recovery of 15N from the OM added to the soil whereas it slightly increased the N recovery from the mineral fertiliser. This suggests that plants and AM fungi probably exert a differential competition for different sources of N available in the soil. On the whole, our results provide a contribution to a better understanding of the conditions under which AM fungi can play an effective role in mitigating the negative effects of nutritional stresses in plants.

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Arbuscular Mycorrhizal Colonization Enhanced Early Growth ofMallotus paniculatusandAlbizia samanunder Nursery Conditions in East Kalimantan, Indonesia

International Journal of Forestry Research ◽

10.1155/2014/898494 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Dewi Wulandari ◽

Saridi ◽

Weiguo Cheng ◽

Keitaro Tawaraya

Keyword(s):

Plant Growth ◽

Nutrient Uptake ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Dry Weight ◽

P Uptake ◽

Forest Conversion ◽

Opencast Mining ◽

Shoot Height ◽

Shoot Dry Weight

Forest over logging, forest fire, forest conversion, and opencast mining have promoted deforestation in Indonesia, and reforestation is needed immediately. However, reforestation is limited by low seedling quality and production, and slow seedling growth in nurseries. Native tropical tree and fast-growing species,Mallotus paniculatusandAlbizia saman, are potential to promote the first rotation of reforestation. Arbuscular mycorrhizal (AM) fungi are known to promote nutrient uptake and plant growth. We examined the effects of two native AM fungi,Gigaspora decipiensandGlomus clarum, on the growth ofM. paniculatusandA. samanseedlings under nursery conditions. At harvest, after six months, we determined AM colonization, shoot dry weight, and shoot N and P concentration. Approximately 90% and 50% ofM. paniculatusandA. samanroots, respectively, were colonized by AM fungi, without any difference between the inoculation treatments.G. decipiensandG. clarumincreased shoot height, leaf number, shoot dry weight, and shoot N and P uptake of both species. A positive correlation was observed between N and P uptake and shoot dry weight. These results suggest that AM fungi are effective in accelerating nutrient uptake and plant growth, which will, in turn, promote reforestation and sustainable forest timber production.

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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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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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Phytohormones Regulate the Development of Arbuscular Mycorrhizal Symbiosis

International Journal of Molecular Sciences ◽

10.3390/ijms19103146 ◽

2018 ◽

Vol 19 (10) ◽

pp. 3146 ◽

Cited By ~ 19

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.

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

Journal of Experimental Botany ◽

10.1093/jxb/eraa538 ◽

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.

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

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-23-7-0915 ◽

2010 ◽

Vol 23 (7) ◽

pp. 915-926 ◽

Cited By ~ 101

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.

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The effect of arbuscular mycorrhizal fungi on total plant nitrogen uptake and nitrogen recovery from soil organic material

The Journal of Agricultural Science ◽

10.1017/s002185961300004x ◽

2013 ◽

Vol 152 (3) ◽

pp. 370-378 ◽

Cited By ~ 30

Author(s):

S. SAIA ◽

E. BENÍTEZ ◽

J. M. GARCÍA-GARRIDO ◽

L. SETTANNI ◽

G. AMATO ◽

...

Keyword(s):

Plant Growth ◽

Organic Material ◽

Mycorrhizal Fungi ◽

N Uptake ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

N Recovery ◽

Plant Nitrogen ◽

Uninoculated Control ◽

Total Plant

SUMMARYArbuscular mycorrhizal (AM) fungi increase nitrogen (N) uptake by their host plants, but their role in plant N capture from soil organic material is still unclear. In particular, it is not clear if AM fungi compete with the host plant for the N coming from the decomposing organic matter (OM), especially when the AM extraradical mycelium (ERM) and plant roots share the same soil volume. The goal of the present research was to study the effects of AM fungi on wheat N capture after the addition of 15N-labelled OM to soil. Durum wheat (Triticum durum) was grown under controlled conditions in a sand:soil mix and the following treatments were applied: (1) AM inoculation with Glomus mosseae and uninoculated control; and (2) soil amended with 15N-enriched maize leaves and unamended soil. The addition of OM reduced plant growth and N uptake. The AM fungi increased both plant growth and N uptake compared with uninoculated control plants and the effect was enhanced when wheat was grown in soil amended with OM compared with the unamended control. Although AM fungi increased soil N mineralization rates and total plant N uptake, they strongly reduced wheat N recovery from OM, suggesting that AM fungi have marked effects on competition between plants and bacteria for the different N sources in soil.

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Contribution of arbuscular mycorrhizal (AM) fungi and hedgerow trees to the yield and nutrient uptake of cassava in an alley-cropping system

The Journal of Agricultural Science ◽

10.1017/s0021859698005516 ◽

1998 ◽

Vol 131 (1) ◽

pp. 79-85 ◽

Cited By ~ 12

Author(s):

O. FAGBOLA ◽

O. OSONUBI ◽

K. MULONGOY

Keyword(s):

Nutrient Uptake ◽

Alley Cropping ◽

Cropping System ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Dry Weight ◽

P Uptake ◽

Root Competition ◽

Woody Legumes ◽

Woody Legume

A field trial on alley-cropping was conducted at the University of Ibadan research farm in the 1990/91 cropping season to assess the contributions of arbuscular mycorrhizal (AM) fungi and hedgerow woody legumes to the yield and nutrient uptake of cassava (Manihot esculenta Crantz) as an intercrop in an infertile soil. The trial also investigated the influence of AM fungi on the interplanting of a non-nodulating woody legume Senna siamea (syn. Cassia siamea) with a nodulating woody legume (Leucaena leucocephala).AM contributions to cassava were greater than the hedgerow contributions, which demonstrated that AM associations are an essential component in the nutrition of cassava. In contrast to cassava, AM inoculation only influenced the leaf dry weight and uptake of nutrients of non-interplanted woody legumes but not the above-ground biomass and P uptake of interplanted woody legumes. However, non-inoculated interplanted Leucaena benefited more from indigenous AM fungi than the competing Senna. The negative contributions to the nutrient uptake (K, Ca and Mg) of cassava by hedgerows and the lack of response to AM inoculation in interplanted hedgerow woody legumes could be attributed to root competition among the different plant species growing in close proximity to each other. The present results show that cassava benefits more from AM association than Leucaena which in turn benefits more than Senna in an alley-cropping system.

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Contribution of arbuscular mycorrhizal symbiosis to in vitro root metal uptake: from trace to toxic metal conditionsThis paper is one of the papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008. Other papers from this meeting are presented in the July 2009 Special Issue of Botany.

Botany ◽

10.1139/b09-062 ◽

2009 ◽

Vol 87 (10) ◽

pp. 913-921 ◽

Cited By ~ 10

Author(s):

Patrick Audet ◽

Christiane Charest

Keyword(s):

Metal Binding ◽

Toxic Metal ◽

In Vitro Study ◽

Arbuscular Mycorrhizal ◽

Am Fungi ◽

Mycorrhizal Symbiosis ◽

Relative Contribution ◽

Am Symbiosis ◽

Metal Contaminant

This in-vitro study investigated the role of arbuscular mycorrhizal (AM) symbiosis in root metal acquisition and stress tolerance from two experiments using a carrot root-organ culture system, and involving the essential micronutrient zinc as a typical metal contaminant. We demonstrated that the AM symbiosis plays a dual role in root metal acquisition by increasing nutrient uptake via mycorrhizal “enhanced uptake” at low (trace) metal concentrations in the growth medium, but then lessening the uptake through “metal-binding” processes at high (toxic) concentrations. Furthermore, we also observed the relative contribution of hyphal uptake and translocation to roots, which led us to suggest that the enhanced uptake and metal-binding processes likely occur simultaneously and (or) independently. Ultimately, symptoms of metal toxicity toward both the roots and AM fungi at the highest Zn exposure concentrations was observed. From this finding, a critical toxicity burden likely exists arising from conditions ranging from trace to toxic metal extremes.

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