scholarly journals Metagenomic Analysis Reveals Reduced Beneficial Microorganism Associations in Roots of Foot Rot Affected Citrus Trees

2021 ◽  
Author(s):  
Chuanyu Yang ◽  
Veronica Ancona
Keyword(s):  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Plant Responses ◽  
Foot Rot ◽  
Fibrous Root ◽  
Phytophthora Spp ◽  
Composition And Structure ◽  
Exophiala Pisciphila ◽  
Fungal Microbiome ◽  
Citrus Trees

Root endophytes have been shown to influence plant growth and plant responses to pathogens. Phytophthora spp. are important pathogens of citrus that cause foot rot and fibrous root decline. We hypothesize that foot rot infection by Phytophthora spp. can result in changes of the endophytic microbial community in citrus roots. Therefore, the endophytic (including bacterial and fungal) microbiome of roots from Phytophthora foot rot affected and healthy citrus trees were analyzed by Illumina sequencing of 16S rRNA and internal transcribed spacer (ITS) amplicons. Results indicate that the composition and structure of the endophytic bacterial and fungal communities were changed in roots of foot rot affected citrus trees. The populations of bacterial genera Asteroleplasma, Pseudomonas and Streptomyces were decreased in foot rot affected trees. Also, the relative abundance of Exophiala pisciphila and Glomeraceae spp. were significantly decreased in citrus roots. Pseudomonas and Streptomyces are considered beneficial bacteria and E. pisciphila and Glomeraceae spp. are dark septate endophytes and arbuscular mycorrhizal fungi respectively, which are involved in citrus health and growth. This study provides a baseline to continue investigating the interactions between the citrus host, Phytophthora spp. and beneficial microbes.

Temporal dynamics of mycorrhizal fungal communities and co-associations with grassland plant communities following experimental manipulation of rainfall

2019 ◽  
Author(s):  
Coline Deveautour ◽  
Sally Power ◽  
Kirk Barnett ◽  
Raul Ochoa-Hueso ◽  
Suzanne Donn ◽  
...  
Keyword(s):  
Community Composition ◽  
Plant Community ◽  
Plant Communities ◽  
Fungal Community ◽  
Mycorrhizal Fungi ◽  
Temporal Dynamics ◽  
Arbuscular Mycorrhizal ◽  
Fungal Communities ◽  
Plant Responses ◽  
Rainfall Regimes

Climate models project overall a reduction in rainfall amounts and shifts in the timing of rainfall events in mid-latitudes and sub-tropical dry regions, which threatens the productivity and diversity of grasslands. Arbuscular mycorrhizal fungi may help plants to cope with expected changes but may also be impacted by changing rainfall, either via the direct effects of low soil moisture on survival and function or indirectly via changes in the plant community. In an Australian mesic grassland (former pasture) system, we characterised plant and arbuscular mycorrhizal (AM) fungal communities every six months for nearly four years to two altered rainfall regimes: i) ambient, ii) rainfall reduced by 50% relative to ambient over the entire year and iii) total summer rainfall exclusion. Using Illumina sequencing, we assessed the response of AM fungal communities sampled from contrasting rainfall treatments and evaluated whether variation in AM fungal communities was associated with variation in plant community richness and composition. We found that rainfall reduction influenced the fungal communities, with the nature of the response depending on the type of manipulation, but that consistent results were only observed after more than two years of rainfall manipulation. We observed significant co-associations between plant and AM fungal communities on multiple dates. Predictive co-correspondence analyses indicated more support for the hypothesis that fungal community composition influenced plant community composition than vice versa. However, we found no evidence that altered rainfall regimes were leading to distinct co-associations between plants and AM fungi. Overall, our results provide evidence that grassland plant communities are intricately tied to variation in AM fungal communities. However, in this system, plant responses to climate change may not be directly related to impacts of altered rainfall regimes on AM fungal communities. Our study shows that AM fungal communities respond to changes in rainfall but that this effect was not immediate. The AM fungal community may influence the composition of the plant community. However, our results suggest that plant responses to altered rainfall regimes at our site may not be resulting via changes in the AM fungal communities.

scholarly journals Señales de reconocimiento entre plantas y hongos formadores de micorrizas arbusculares

2010 ◽  
Vol 11 (1) ◽  
pp. 53 ◽  
Author(s):  
Margarita Ramírez Gómez ◽  
Alia Rodríguez Villate
Keyword(s):  
Plant Defense ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Terrestrial Ecosystems ◽  
Defense Responses ◽  
Plant Responses ◽  
Nutrient Exchange ◽  
Mycorrhizal Association ◽  
Host Defense System ◽  
Plant Families

<p>La asociación entre Hongo formadores de micorrizas arbusculares (HFMA) y las plantas ha permitido la adaptación de éstas a ecosistemas terrestres, presentándose en más del 80% de las plantas. El hospedero suministra carbohidratos al hongo y éste transporta los nutrientes que la planta requiere. El establecimiento de la simbiosis requiere procesos armónicos a nivel espacio-temporal, que dependen de señales específicas, para reconocimiento, colonización e intercambio de nutrientes. Las plantas presentan respuestas de defensa frente a la posible invasión de microorganismos, sin embargo, en la simbiosis éstas son débiles, localizadas y no impiden la colonización del hongo. Estas señales se observan en todas las etapas de la simbiosis, siendo la primera señal enviada por la planta en exudados de la raíz, especialmente en condiciones de bajo fósforo. Posteriormente los HFMA activan la expresión de genes que favorecen cambios a nivel celular para la formación del apresorio, del aparato de pre-penetración y en células de la corteza, del arbúsculo y la membrana periarbuscular, para el intercambio de nutrientes. Un aspecto de interés está relacionado con los mecanismos de atenuación de las respuestas de defensa de la planta. Se han planteado diversas hipótesis para entender este fenómeno y aunque el control de la simbiosis está regulado principalmente por la planta, aún se desconoce si los HFMA generan señales que facilitan el debilitamiento de las respuestas de defensa del hospedero. Este documento está orientado a hacer una revisión de las señales de reconocimiento HFMA - plantas para cada fase de la simbiosis, así como de algunos mecanismos de regulación de las respuestas de defensa de la planta para el establecimiento de la simbiosis.</p><p> </p><p><strong>Recognition Signalling Between Arbuscular Mycorrhizal Fungi (AMF) and Plants</strong></p><p> </p>The arbuscular mycorrhizal association has been instrumental for plant adaptation to terrestrial ecosystems over the last 400 million years. It is known that more than 80% of plant families form this symbiosis .Thus, nutrient exchange and protection from pathogens are thought to be key elements in the symbiosis. For the establishment of the association, harmonic processes for recognition, colonization and nutrients exchange are required both at temporal and space level. Plants react against microorganisms attack by producing defense responses, however, in the case of AM association, plant responses are weak, localized and do not stop colonization by the fungus. Signals are observed along the whole symbiosis process, being the first one produced by the plant through root exudates as a response for P stress. Then, AMF activate genes involved in plant cellular changes required for arbuscle formation, pre-penetration apparatus and at cortex level, the formation of periarbuscular membrane for the bi-directional nutrient exchange. Interestingly, several hypotheses have been formulated to explain the plant defense attenuation. For example, the activation of defense suppressors, the existence of plants with no defence responses to AMF and the existence of plants that suppress their defense response, among others. It is unknown whether the fungi induce low response levels from the host defense system. This document focuses on the signaling recognition between AMF and plants in each symbiosis phase and on the regulation mechanisms of the plant defense responses for the symbiosis establishment.

scholarly journals Unique transcriptome features of pea (Pisum sativum L.) lines with differing responses to beneficial soil microorganisms

2021 ◽  
Vol 19 (2) ◽  
pp. 131-141
Author(s):  
Alexey M. Afonin ◽  
Emma S. Gribchenko ◽  
Evgeny A. Zorin ◽  
Anton S. Sulima ◽  
Daria A. Romanyuk ◽  
...  
Keyword(s):  
Pisum Sativum ◽  
Mycorrhizal Fungi ◽  
Soil Microorganisms ◽  
Molecular Mechanisms ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Arbuscular Mycorrhizal ◽  
Plant Responses ◽  
Single Nucleotide Variants ◽  
Interaction Efficiency

BACKGROUND: Garden pea (Pisum sativum L.) possesses the ability to form beneficial symbioses with various soil microorganisms. However, different pea cultivars, genotypes, and lines gain more or less benefit from these interactions, so the trait named efficiency of interaction with soil microorganisms (EIBSM) was suggested to describe this phenomenon. The molecular mechanisms underlying the manifestation of the EIBSM trait are not properly studied, and only few works focusing on plant responses to combined microbial preparations have been published to date. METHODS: Eight pea lines previously described as contrasting in manifestation of the EIBSM trait were grown in pots with soil under combined inoculation with nodule bacteria and arbuscular mycorrhizal fungi, and the transcriptome profiles of the whole root systems of the plants were investigated using 3'MACE RNA sequencing. RESULTS: The relatedness of the lines inferred from the analysis of transcripts SNVs (Single Nucleotide Variants) corresponded to the manifestation of the EIBSM trait: three high-EIBSM lines and three low-EIBSM lines formed two distinct clusters. Thus, the gene expression profiles were compared between these two clusters, which enabled identification of transcriptome signatures characteristic for each group. The lines previously described as high-EIBSM have lower symbiotic activity, and the expression levels of pathogen response genes were elevated compared to the lines with low EIBSM. CONCLUSION: This result suggests that the mechanism of high interaction efficiency may be connected to stricter host control of symbionts, allowing such plants to expend less on the symbioses.

scholarly journals Germinating Spore Exudates from Arbuscular Mycorrhizal Fungi: Molecular and Developmental Responses in Plants and Their Regulation by Ethylene

2011 ◽  
Vol 24 (2) ◽  
pp. 260-270 ◽  
Author(s):  
Arijit Mukherjee ◽  
Jean-Michel Ané
Keyword(s):  
Gene Expression ◽  
Genetic Control ◽  
Root Development ◽  
Mycorrhizal Fungi ◽  
Root Architecture ◽  
Glomus Intraradices ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Plant Responses ◽  
Symbiotic Gene

Arbuscular mycorrhizal (AM) fungi stimulate root development and induce expression of mycorrhization-specific genes in both eudicots and monocots. Diffusible factors released by AM fungi have been shown to elicit similar responses in Medicago truncatula. Colonization of roots by AM fungi is inhibited by ethylene. We compared the effects of germinating spore exudates (GSE) from Glomus intraradices in monocots and in eudicots, their genetic control, and their regulation by ethylene. GSE modify root architecture and induce symbiotic gene expression in both monocots and eudicots. The genetic regulation of root architecture and gene expression was analyzed using M. truncatula and rice symbiotic mutants. These responses are dependent on the common symbiotic pathway as well as another uncharacterized pathway. Significant differences between monocots and eudicots were observed in the genetic control of plant responses to GSE. However, ethylene inhibits GSE-induced symbiotic gene expression and root development in both groups. Our results indicate that GSE signaling shares similarities and differences in monocots versus eudicots, that only a subset of AM signaling pathways has been co-opted in legumes for the establishment of root nodulation with rhizobia, and that regulation of these pathways by ethylene is a feature conserved across higher land plants.

Influence of a Bacillus sp. on physiological activities of two arbuscular mycorrhizal fungi and on plant responses to PEG-induced drought stress

Mycorrhiza ◽  
2003 ◽  
Vol 13 (5) ◽  
pp. 249-256 ◽  
Author(s):  
Astrid Vivas ◽  
Adriana Marulanda ◽  
Juan Manuel Ruiz-Lozano ◽  
Jos� Miguel Barea ◽  
Rosario Azc�n
Keyword(s):  
Drought Stress ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Arbuscular Mycorrhizal ◽  
Plant Responses ◽  
Bacillus Sp

Contribution of Arbuscular Mycorrhizal Inoculation to the Growth and Photosynthesis of Mulberry in Karst Rocky Desertification Area

2014 ◽  
Vol 488-489 ◽  
pp. 769-773 ◽  
Author(s):  
Ke Chen ◽  
Song Mei Shi ◽  
Xiao Hong Yang ◽  
Xian Zhi Huang
Keyword(s):  
Mycorrhizal Fungi ◽  
Photosynthetic Capacity ◽  
Growth Parameters ◽  
Physiological Responses ◽  
Arbuscular Mycorrhizal ◽  
Root Number ◽  
Fibrous Root ◽  
Karst Rocky Desertification ◽  
Rocky Desertification ◽  
Mycorrhizal Inoculation

The photosynthesis effect of arbuscular mycorrhizal fungi (AMF) on mulberry was evaluated in karst rocky desertification area. Three-month-old sterile mulberry saplings were transplanted in karst rocky desertification area and were inoculated with Gigaspora rosea. Some growth parameters and photosynthesis indexes were measured to study the physiological responses after inoculating for 1 year. The results showed mulberries that were inoculated with AMF had greater height, larger stem diameter and leaf area, more leaf number per plant, more fibrous root number and biomass of shoots and roots, as well as higher chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance compared with non-AMF plants. The research results confirmed that AMF markedly enhanced the absorptive ability of root system, promoted the vegetative growth, improved the photosynthetic capacity, and obviously increased mulberry survival rate in karst rocky desertification area. These results provided a theoretical base for the ecological restoration in karst rocky desertification area.

scholarly journals Mechanisms for tolerance to water-deficit stress in plants inoculated with arbuscular mycorrhizal fungi. A review

2016 ◽  
Vol 34 (2) ◽  
pp. 179-189 ◽  
Author(s):  
John Cristhian Fernández-Lizarazo ◽  
Liz Patricia Moreno-Fonseca
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Water Deficit ◽  
Mycorrhizal Fungi ◽  
Water Status ◽  
Arbuscular Mycorrhizal ◽  
Co2 Assimilation ◽  
Water Deficit Stress ◽  
Plant Responses ◽  
Stress Signal ◽  
Negative Effect

The expansion of areas affected by drought worldwide has a negative effect on yield and crops production, making water deficits the most significant abiotic stress that limits the growth and development of plants. The use of arbuscular mycorrhizal fungi (AMF) is a strategy that mitigates the effects of this stress in a sustainable way, given the increase in the tolerance to water deficit stress in plants inoculated with these fungi; however, the exact mechanism is unknown because the response depends on the water-deficit stress type and is specific to the AMF and the plant. This review describes the mechanisms that explain how the AMF colonization of roots can modify the response of plants during a water deficit, as well as its relationship with physiological processes that determine yield, photosynthesis and photoassimilate partitioning. These mechanisms may include modifications in the content of plant hormones, such as strigolactones, jasmonic acid (JA) and absicic acid (ABA). The JA appears to be involved in the stress signal in mycorrhizal plants through an increase of ABA concentrations and, at the same time, ABA has a regulating effect on strigolactone concentrations. Also, there is improvement of plant water status, stomatal conductance, nutritional status and plant responses to cope with a water deficit, such as osmotic adjustment, and antioxidant activity. These modifications cause an increase in CO2 assimilation and photoassimilate production, improving plant growth during a drought.

scholarly journals Funneliformis mosseae Improves Growth and Nutrient Accumulation in Wheat by Facilitating Soil Nutrient Uptake under Elevated CO2 at Daytime, Not Nighttime

2021 ◽  
Vol 7 (6) ◽  
pp. 458
Author(s):  
Songmei Shi ◽  
Xie Luo ◽  
Miao Wen ◽  
Xingshui Dong ◽  
Sharifullah Sharifi ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
Mycorrhizal Fungi ◽  
Plant Biomass ◽  
Cropping Systems ◽  
Soil Nutrient ◽  
Arbuscular Mycorrhizal ◽  
Plant Responses ◽  
Wheat Seedlings ◽  
Available N ◽  
Funneliformis Mosseae

The concurrent effect of elevated CO2 (eCO2) concentrations and arbuscular mycorrhizal fungi (AMF) on plant growth, carbon (C), nitrogen (N), phosphorus (P) and potassium (K) accumulations in plant and soil is largely unknown. To understand the mechanisms of eCO2 and mycorrhization on wheat (Triticum aestivum) performance and soil fertility, wheat seedlings were grown under four different CO2 environments for 12 weeks, including (1) ambient CO2 (ACO2, 410/460 ppm, daytime/nighttime), (2) sole daytime eCO2 (DeCO2, 550/460 ppm), (3) sole nighttime eCO2 (NeCO2, 410/610 ppm), and (4) dual or continuous daytime/nighttime eCO2 ((D + N)eCO2, 550/610 ppm), and with or without AMF (Funneliformis mosseae) colonization. DeCO2, NeCO2 and (D + N)eCO2 generally significantly increased shoot and root biomass, plant C, N, P and K accumulation, soil invertase and urease activity, but decreased shoot and root N, P and K concentrations, and soil available N, P and K. Compared with non-AMF, AMF effects on above-mentioned characteristics were significantly positive under ACO2, DeCO2 and (D + N)eCO2, but negative on plant biomass, C, N, P and K accumulation under NeCO2. Overall, AMF colonization alleviated soil nutrient constraints on plant responses to DeCO2, while NeCO2 decreased AMF’s beneficial effects on plants. These results demonstrated that an integration of AMF’s benefits to plants under factual field DeCO2 and/or NeCO2 will be critical for managing the long-term consequence of future CO2 rising on global cropping systems.

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