scholarly journals Effect of fungal, oomycete and nematode interactions on apple root development in replant soil

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Emma L. Tilston ◽  
Gregory Deakin ◽  
Julie Bennett ◽  
Thomas Passey ◽  
Nicola Harrison ◽  
...  
Keyword(s):  
Root Development ◽  
Fungal Pathogens ◽  
Soil Microbial Communities ◽  
Pathogenic Fungi ◽  
Competitive Interactions ◽  
Apple Replant Disease ◽  
Soil Microbial ◽  
Single Organism ◽  
Root Tissues ◽  
Root Lesion Nematodes

Abstract Background Apple replant disease (ARD) is a phenomenon associated with poor tree establishment at sites where the same, or a closely-related species, has grown for at least 1–2 years. No single organism has been identified as the universal causal agent, but there is increasing evidence that multiple soil-borne plant pathogenic fungi and oomycetes form an ARD disease complex. Root damage caused by root lesion nematodes has also been implicated in facilitating the entry of pathogens into root tissues resulting in the development of severe ARD. Methods We used a reductionist approach to determine effects of one or more members of the ARD complex on ARD in a number of selected rootstock genotypes with contrasting characteristics. Through a 15-month pot-based experiment in which semi-selective biocides were applied to soil from a replant orchard, we investigated (1) the nature of the interactions (i.e. antagonistic, additive or synergistic) between different groups of soil biota and ARD severity, and (2) whether rootstock characteristics modify ARD severity. Results There might be competitive interactions between oomycetes and fungal pathogens in infecting apple roots and hence subsequent ARD development. Controlling all three ARD components (oomycetes, fungi, and nematodes) led to the best root development. However, these effects on root development were not manifested in the above-ground tree development 15 months after treatment. Specific soil biocide treatments against fungi and oomycetes led to large changes in soil microbial communities whereas the nematicide treatment led to least changes. In spite of the observed ARD, comparing rhizosphere microbial sequences among treatments failed to reveal candidate pathogens for ARD. Conclusions Candidate ARD oomycetes and fungal pathogens are likely to engage in competitive interactions among themselves in infecting apple roots. Although soil amendments affected soil microbiota, such effects appear to be very unpredictable.

scholarly journals Continuous monocropping highly affect the composition and diversity of microbial communities in peanut (Arachis hypogaea L.)

2021 ◽  
Vol 49 (4) ◽  
pp. 12532
Author(s):  
Ali I. MALLANO ◽  
Xianli ZHAO ◽  
Yanling SUN ◽  
Guangpin JIANG ◽  
Huang CHAO
Keyword(s):  
Microbial Communities ◽  
Management Practices ◽  
Rhizosphere Soil ◽  
Diversity Index ◽  
Cropping Systems ◽  
Soil Microbial Communities ◽  
Pathogenic Fungi ◽  
Continuous Cropping ◽  
Bacterial Phyla ◽  
Soil Microbial

Continuous cropping systems are the leading cause of decreased soil biological environments in terms of unstable microbial population and diversity index. Nonetheless, their responses to consecutive peanut monocropping cycles have not been thoroughly investigated. In this study, the structure and abundance of microbial communities were characterized using pyrosequencing-based approach in peanut monocropping cycles for three consecutive years. The results showed that continuous peanut cultivation led to a substantial decrease in soil microbial abundance and diversity from initial cropping cycle (T1) to later cropping cycle (T3). Peanut rhizosphere soil had Actinobacteria, Protobacteria, and Gemmatimonadetes as the major bacterial phyla. Ascomycota, Basidiomycota were the major fungal phylum, while Crenarchaeota and Euryarchaeota were the most dominant phyla of archaea. Several bacterial, fungal and archaeal taxa were significantly changed in abundance under continuous peanut cultivation. Bacterial orders, Actinomycetales, Rhodospirillales and Sphingomonadales showed decreasing trends from T1>T2>T3. While, pathogenic fungi Phoma was increased and beneficial fungal taxa Glomeraceae decreased under continuous monocropping. Moreover, Archaeal order Nitrososphaerales observed less abundant in first two cycles (T1&T2), however, it increased in third cycle (T3), whereas, Thermoplasmata exhibit decreased trends throughout consecutive monocropping. Taken together, we have shown the taxonomic profiles of peanut rhizosphere communities that were affected by continuous peanut monocropping. The results obtained from this study pave ways towards a better understanding of the peanut rhizosphere soil microbial communities in response to continuous cropping cycles, which could be used as bioindicator to monitor soil quality, plant health and land management practices.

scholarly journals Full-Season Cover Crops and Their Traits That Promote Agroecosystem Services

Agriculture ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 830
Author(s):  
Cameron Wagg ◽  
Aafke van Erk ◽  
Erica Fava ◽  
Louis-Pierre Comeau ◽  
T. Fatima Mitterboeck ◽  
...  
Keyword(s):  
Cover Crops ◽  
Aboveground Biomass ◽  
Fungal Pathogens ◽  
Soil Microbial Communities ◽  
Weed Suppression ◽  
Soil Nitrate ◽  
Soil Microbial ◽  
Rooting Density ◽  
Local Ecosystem ◽  
Selection Of

Non-marketable crops are increasingly being used as a tool to promote agroecosystem services and sustainable agriculture. Nevertheless, crops vary greatly in the traits by which they capture resources and influence the local ecosystem. Here we report on the traits and associated soil microbial communities that relate to aboveground biomass production, nutrient capture, weed suppression, erosion control and building particulate organic matter of 22 different full-season cover crops. All agroecosystem services were positively correlated with maximum canopy height and leaf area. Rooting density was positively associated with indices of bacterial diversity. While some legumes produced the greatest standing N and P in aboveground biomass, they were also poor at capturing soil nitrate and promoted high levels of potential plant fungal pathogens. Conversely, Brassicaceae crops had the lowest levels of potential plant fungal pathogens, but also suppressed saprophytic fungi and rhizobia. Thus, not all crops are equal in their ability to promote all agroecosystem services, and while some crops may be ideal for promoting a specific agroecosystem service, this could result in a trade-off with another. Nonetheless, our study demonstrates that plant functional traits are informative for the selection of crops for promoting agroecosystem services.

scholarly journals Microbial Community Changes in the Rhizosphere Soil of Healthy and Rusty Panax ginseng and Discovery of Pivotal Fungal Genera Associated with Rusty Roots

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Xuemin Wei ◽  
Xiaoyue Wang ◽  
Pei Cao ◽  
Zitong Gao ◽  
Amanda Juan Chen ◽  
...  
Keyword(s):  
Microbial Community ◽  
Panax Ginseng ◽  
Soil Microbial Community ◽  
Fungal Pathogens ◽  
High Throughput Sequencing ◽  
Microbial Community Composition ◽  
Pathogenic Fungi ◽  
Linear Discriminant ◽  
Rhizosphere Soils ◽  
Soil Microbial

Panax ginseng Meyer, a valuable medicinal plant, is severely threatened by rusty root, a condition that greatly affects its yield and quality. Studies investigating the relationship between soil microbial community composition and rusty roots are vital for the production of high-quality ginseng. Here, high-throughput sequencing was employed to systematically characterize changes in the soil microbial community associated with rusty roots. Fungal diversity was lower in the soils of rusty root-affected P. ginseng than in those of healthy plants. Importantly, principal coordinate analysis separated the fungal communities in the rhizosphere soils of rusty root-affected ginseng from those of healthy plants. The dominant bacterial and fungal genera differed significantly between rhizosphere soils of healthy and rusty root-affected P. ginseng, and linear discriminant analysis effect size (LEfSe) further indicated a strong imbalance in the soil microbial community of diseased plants. Significantly enriched bacterial genera (including Rhodomicrobium, Knoellia, Nakamurella, Asticcacaulis, and Actinomadura) were mainly detected in the soil of rusty root-affected P. ginseng, whereas significantly enriched fungal genera (including Xenopolyscytalum, Arthrobotrys, Chalara, Cryptococcus, and Scutellinia) were primarily detected in the soil of healthy plants. Importantly, five fungal genera (Cylindrocarpon, Acrophialophora, Alternaria, Doratomyces, and Fusarium) were significantly enriched in the soil of rusty root-affected plants compared with that of healthy plants, suggesting that an increase in the relative abundance of these pathogenic fungi (Cylindrocarpon, Alternaria, and Fusarium) may be associated with ginseng rusty roots. Additionally, this study is the first to report that an increase in the relative abundances of Acrophialophora and Doratomyces in the rhizosphere of P. ginseng may be associated with the onset of rusty root symptoms in this plant. Our findings provide potentially useful information for developing biological control strategies against rusty root, as well as scope for future screening of fungal pathogens in rusty roots of P. ginseng.

scholarly journals Screening of Rhizosphere Bacteria and Nematode Populations Associated with Soybean Roots in the Mpumalanga Highveld of South Africa

2021 ◽  
Vol 9 (9) ◽  
pp. 1813
Author(s):  
Gerhard Engelbrecht ◽  
Sarina Claassens ◽  
Charlotte M. S. Mienie ◽  
Hendrika Fourie
Keyword(s):  
Parasitic Nematode ◽  
Soil Microbial Communities ◽  
Plant Parasitic Nematode ◽  
Rhizosphere Bacteria ◽  
Bacterial Strains ◽  
Linear Discriminant ◽  
Soil Microbial ◽  
Root Lesion Nematodes ◽  
Next Generation Sequencing Ngs ◽  
Plant Parasitic

Soybean is among South Africa’s top crops in terms of production figures. Over the past few years there has been increasingly more damage caused to local soybean by plant-parasitic nematode infections. The presence of Meloidogyne (root-knot nematodes) and Pratylenchus spp. (root lesion nematodes) in soybean fields can cripple the country’s production, however, little is known about the soil microbial communities associated with soybean in relation to different levels of Meloidogyne and Pratylenchus infestations, as well as the interaction(s) between them. Therefore, this study aimed to identify the nematode population assemblages and endemic rhizosphere bacteria associated with soybean using Next Generation Sequencing (NGS). The abundance of bacterial genera that were then identified as being significant using linear discriminant analysis (LDA) Effect Size (LEfSe) was compared to the abundance of the most prevalent plant-parasitic nematode genera found across all sampled sites, viz. Meloidogyne and Pratylenchus. While several bacterial genera were identified as significant using LEfSe, only two with increased abundance were associated with decreased abundance of Meloidogyne and Pratylenchus. However, six bacterial genera were associated with decreased Pratylenchus abundance. It is therefore possible that endemic bacterial strains can serve as an alternative method for reducing densities of plant-parasitic nematode genera and in this way reduce the damages caused to this economically important crop.

scholarly journals Cross-Site Soil Microbial Communities under Tillage Regimes: Fungistasis and Microbial Biomarkers

2012 ◽  
Vol 78 (23) ◽  
pp. 8191-8201 ◽  
Author(s):  
Timo P. Sipilä ◽  
Kim Yrjälä ◽  
Laura Alakukku ◽  
Ansa Palojärvi
Keyword(s):  
Microbial Communities ◽  
Fungal Biomass ◽  
Management Strategies ◽  
Soil Microbial Communities ◽  
Pathogenic Fungi ◽  
Plant Pathogenic Fungi ◽  
Content Type ◽  
Soil Microbial ◽  
No Till ◽  
Cross Site

ABSTRACTThe exploitation of soil ecosystem services by agricultural management strategies requires knowledge of microbial communities in different management regimes. Crop cover by no-till management protects the soil surface, reducing the risk of erosion and nutrient leaching, but might increase straw residue-borne and soilborne plant-pathogenic fungi. A cross-site study of soil microbial communities andFusariumfungistasis was conducted on six long-term agricultural fields with no-till and moldboard-plowed treatments. Microbial communities were studied at the topsoil surface (0 to 5 cm) and bottom (10 to 20 cm) by general bacterial and actinobacterial terminal restriction fragment length polymorphism (T-RFLP) and phospholipid fatty acid (PLFA) analyses.Fusarium culmorumsoil fungistasis describing soil receptivity to plant-pathogenic fungi was explored by using the surface layer method. Soil depth had a significant impact on general bacterial as well as actinobacterial communities and PLFA profiles in no-till treatment, with a clear spatial distinction of communities (P< 0.05), whereas the depth-related separation of microbial communities was not observed in plowed fields. The fungal biomass was higher in no-till surface soil than in plowed soil (P< 0.07). Soil total microbial biomass and fungal biomass correlated with fungistasis (P< 0.02 for the sum of PLFAs;P< 0.001 for PLFA 18:2ω6). Our cross-site study demonstrated that agricultural management strategies can have a major impact on soil microbial community structures, indicating that it is possible to influence the soil processes with management decisions. The interactions between plant-pathogenic fungi and soil microbial communities are multifaceted, and a high level of fungistasis could be linked to the high microbial biomass in soil but not to the specific management strategy.

scholarly journals Biocontrol Potential of The Phloridin-Degrading Bacillus Licheniformis XNRB-3 Against Apple Replant Disease

2021 ◽  
Author(s):  
Duan Yanan ◽  
Zhao Lei ◽  
Jiang Weitao ◽  
Chen Ran ◽  
Zhang Rong ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Phenolic Acids ◽  
Bacillus Licheniformis ◽  
Pathogenic Fungi ◽  
Effective Control ◽  
Control Effect ◽  
Apple Replant Disease ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Replant Disease

Abstract Background: Apple replant disease (ARD) is a common occurrence in many major apple-growing areas worldwide, seriously hindering the development of the apple industry. To avoid the shortcomings of chemical fungicides currently used to control ARD, it is necessary to find sustainable and effective control methods. Here, an endophytic phloridin-degrading Bacillus licheniformis XNRB-3 was isolated from the root tissue of healthy apple trees, and its control effect on apple replant disease (ARD) and its how to alleviates the pathogen pressure via changes in soil microbiomes were studied.Results: The addition of strain XNRB-3 in Fusarium infested soils significantly reduced the number of pathogens in the soil, thus resulting in a lower disease incidence, and the relative control effect reached more than 60%. The fermentation broth can also protect the roots of the plants from Fusarium infection. These antagonistic effects were further validated using an in vitro assay in which the pathogen control was related to growth and spore germination inhibition via directly secreted antimicrobial substances and and indirect interspecific competition for nutrients. The antifungal organic compounds in the fermentation metabolites were identified using GC-MS technology. Among them, alpha-bisabolol and 2,4-di-tert-butylphenol had significant inhibitory effects on many planted pathogenic fungi. Butanedioic acid, monomethyl ester, and dibutyl phthalate can promote the root elongation and lateral root development of Arabidopsis plants. The potential of strain XNRB-3 to control ARD was later validated using microbial fertilizer inoculation in pot and field experiment. The addition of strain XNRB-3 significantly promoted the growth of plants, and the activity of enzymes related to disease resistance (SOD, POD, and CAT) was also significantly enhanced. It also reduced the abundance of Fusarium and the content of phenolic acids in the rhizosphere soil, improved soil microbial community structure and nutritional conditions, and increased soil microbial diversity and activity, as well as soil enzyme activity. Conclusions: The incorporation of strain XNRB-3 in the soil alleviated the damage of soil-borne pathogens to plants by reducing the relative abundance of pathogenic fungi and the content of phenolic acids, and inducing disease resistance of plants. Taken together, B. licheniformis XNRB-3 could be developed into a promising biocontrol and plant-growth-promoting agent. This provides a new management strategy to control ARD.

SOYBEAN AND FLAX SELECTION METHODS

1970 ◽  
pp. 19-23
Author(s):  
V. М. Lukomets ◽  
S. V. Zelentsov
Keyword(s):  
High Resistance ◽  
Fungal Pathogens ◽  
Selection Process ◽  
Pathogenic Fungi ◽  
Cultivated Plants ◽  
Practical Implementation ◽  
Physiological Basis ◽  
Oil Crops ◽  
Soybean Genotypes ◽  
Genetically Determined

To improve the effectiveness of the soybeans and oil flax breeding, research to improve existing and develop new breeding methods are conducting in all-Russia Research institute of Oil Crops (Krasnodar). One of the improved methods for the soybean breeding, based on the use of sources of complexes of compensatory genes, is the CCG technology, which allows to create varieties with an increased yield of a heterotic level transmitted along the progeny for the entire life cycle of the variety. For the purpose of non-transgenic production of new traits, a theory of polyploid recombination of the genome (TPR) was formulated, which models the mechanism of the natural formation of polymorphism in the centers of origin of cultivated plants. On the basis of this theory, a method of breeding (TPR-technology) has been developed, which makes it possible to obtain recombinant reploids of soybeans and oil flax with an extended spectrum of traits. Of these reploids, the soybean lines with increased sucking force of the roots, providing high drought resistance, were distinguished; cold-resistant soybean lines, which stand in the phase of shoots of freezing to minus 5 °С; lines of oil flax with complete resistance to flax sickness of soil and high resistance to Fusarium; winter-hardy flax lines that withstand winter frosts down to minus 20–23 °С and ripen one and a half months earlier than spring sowings. Another original developed method is the ODCS-technology for isolating and selecting soybean genotypes with high resistance to fungal pathogens. The physiological basis of ODCS-technology is the blocking of osmotic nutrition of pathogenic fungi due to genetically determined increased osmotic pressure in the tissues of host plants. The practical implementation of CCG-, TPR- and ODKS-technologies in the selection process, allowed to create a whole series of soybean and oil flax varieties with improved or new traits.

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