Plant colonization of a restored wetland in northern Kentucky: Contribution of seeding vs. natural sourcesa

Endophytic bacteria hold tremendous potential for use as biocontrol agents. Our study aimed to investigate the biocontrol activity of Pseudomonas fluorescens BRZ63, a new endophyte of oilseed rape (Brassica napus L.) against Rhizoctonia solani W70, Colletotrichum dematium K, Sclerotinia sclerotiorum K2291, and Fusarium avenaceum. In addition, features crucial for biocontrol, plant growth promotion, and colonization were assessed and linked with the genome sequences. The in vitro tests showed that BRZ63 significantly inhibited the mycelium growth of all tested pathogens and stimulated germination and growth of oilseed rape seedlings treated with fungal pathogens. The BRZ63 strain can benefit plants by producing biosurfactants, siderophores, indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, and ammonia as well as phosphate solubilization. The abilities of exopolysaccharide production, autoaggregation, and biofilm formation additionally underline its potential to plant colonization and hence biocontrol. The effective colonization properties of the BRZ63 strain were confirmed by microscopy observations of EGFP-expressing cells colonizing the root surface and epidermal cells of Arabidopsis thaliana Col-0. Genome mining identified many genes related to the biocontrol process, such as transporters, siderophores, and other secondary metabolites. All analyses revealed that the BRZ63 strain is an excellent endophytic candidate for biocontrol of various plant pathogens and plant growth promotion.

Download Full-text

Planting native trees to restore riparian forests increases biotic resistance to non-native plant invasions

Invasive Plant Science and Management ◽

10.1017/inp.2021.11 ◽

2021 ◽

pp. 1-24

Author(s):

Chad F. Hammer ◽

John S. Gunn

Keyword(s):

United States ◽

Ecosystem Service ◽

Invasive Plant ◽

Biotic Resistance ◽

The United States ◽

Tree Regeneration ◽

Tree Planting ◽

Plant Colonization ◽

Native Plant ◽

Native Trees

Abstract Non-native invasive plant species are a major cause of ecosystem degradation and impairment of ecosystem service benefits in the United States. Forested riparian areas provide many ecosystem service benefits and are vital to maintaining water quality of streams and rivers. These systems are also vulnerable to natural disturbances and invasion by non-native plants. We assessed whether planting native trees on disturbed riparian sites may increase biotic resistance to invasive plant establishment in central Vermont in the northeastern United States. The density (stems/m2) of invasive stems was higher in non-planted sites (x̄=4.1 stems/m2) compared to planted sites (x̄=1.3 stems/m2). More than 90% of the invasive plants were Japanese knotweed (Fallopia japonica). There were no significant differences in total stem density of native vegetation between planted and non-planted sites. Other measured response variables such as native tree regeneration, species diversity, soil properties and soil function showed no significant differences or trends in the paired riparian study sites. The results of this case study indicate that tree planting in disturbed riparian forest areas may assist conservation efforts by minimizing the risk of invasive plant colonization.

Download Full-text

Functional ecology of the biological soil crust in semiarid SE Spain: sun and shade populations of Diploschistes diacapsis (Ach.) Lumbsch.

The Lichenologist ◽

10.1017/s0024282905015021 ◽

2005 ◽

Vol 37 (5) ◽

pp. 425-432 ◽

Cited By ~ 38

Author(s):

Ana PINTADO ◽

Leopoldo G. SANCHO ◽

T. G. Allan GREEN ◽

José Manuel BLANQUER ◽

Roberto LÁZARO

Keyword(s):

Water Content ◽

Chlorophyll Content ◽

Unit Area ◽

Biological Soil Crust ◽

Dry Weight ◽

Mean Annual Precipitation ◽

Plant Colonization ◽

Soil Crust ◽

Active Time ◽

Exposed Population

The Tabernas badlands in semiarid south-east Spain is one of the driest regions in Europe with a mean annual precipitation of c. 240 mm. The landscape is deeply dissected, with canyons, ramblas and sparsely vegetated eroded badland slopes. The vegetation is predominantly a biological soil crust consisting of different types of lichen-rich communities, one of the more conspicuous being dominated by Diploschistes diacapsis (Ach.) Lumbsch. This lichen is mainly restricted to the north- facing slopes, where it forms extensive whitish carpets and probably plays an important role in preventing erosion of the slopes and allowing plant colonization. South-facing slopes are much more eroded and generally lack vegetation. %The photosynthetic performance of north (shade) and south-facing (sun) populations of D. diacapsis was studied to determine if these different populations showed any adaptations to the microclimatic conditions of their individual habitats. The response of CO2 exchange to light intensity, temperature and water content was measured under controlled conditions in the laboratory. Dry weight-based net photosynthetic rates were higher in the southern-exposed population but quantum efficiency, and light compensation points were similar. Thallus weight per unit area (LMA) was considerably higher for shade specimens but maximum water content and optimal water content were very similar and chlorophyll content on a dry weight basis was also similar. Chlorophyll content on an area basis was higher in the northern-exposed population and always much larger than those reported in other studies on the same species (up to 8 times larger) with the result that NP values on a chlorophyll basis were relatively low. The larger LMA meant that shade thalli stored more water per unit area which should ensure longer active periods than sun thalli. The results support a strategy pair of high NP and short active time versus low NP and long active time, both having been reported for other soil crust species. However, the visibly larger biomass of the shade D. diacapsis suggests that the lichen is at the limit of its adaptability in these habitats.

Download Full-text

Nitric oxide signalling in plant interactions with pathogenic fungi and oomycetes

Journal of Experimental Botany ◽

10.1093/jxb/eraa596 ◽

2020 ◽

Author(s):

Tereza Jedelská ◽

Lenka Luhová ◽

Marek Petřivalský

Keyword(s):

Nitric Oxide ◽

Current Knowledge ◽

Biotic Interactions ◽

Decisive Role ◽

Pathogenic Fungi ◽

Plant Colonization ◽

No Production ◽

Plant Interactions ◽

Oriented Growth ◽

Plant Pathogen Interactions

Abstract Nitric oxide (NO) and reactive nitrogen species have emerged as crucial signalling and regulatory molecules across all organisms. In plants, fungi and fungi-like oomycetes, NO is involved in the regulation of multiple processes during their growth, development, reproduction, responses to the external environment and biotic interactions. It has become evident that NO is produced and used as signalling and defence cues by both partners in multiple forms of plant interactions with their microbial counterparts, ranging from symbiotic to pathogenic modes. This review summarizes current knowledge on NO role in plant-pathogen interactions, focused on biotrophic, necrotrophic and hemibiotrophic fungi and oomycetes. Actual advances and gaps in the identification of NO sources and fate in plant and pathogen cells are discussed. We review the decisive role of time- and site-specific NO production in germination, oriented growth and active penetration of filamentous pathogens to the host tissues, as well in pathogen recognition, and defence activation in plants. Distinct functions of NO are highlighted on diverse interactions of host plants with fungal and oomycete pathogens of different lifestyles, where NO in interplay with reactive oxygen species govern successful plant colonization, cell death and resistance establishment.

Download Full-text

Metabolic Modeling of Pectobacterium parmentieri SCC3193 Provides Insights into Metabolic Pathways of Plant Pathogenic Bacteria

Microorganisms ◽

10.3390/microorganisms7040101 ◽

2019 ◽

Vol 7 (4) ◽

pp. 101 ◽

Cited By ~ 5

Author(s):

Sabina Zoledowska ◽

Luana Presta ◽

Marco Fondi ◽

Francesca Decorosi ◽

Luciana Giovannetti ◽

...

Keyword(s):

In Silico ◽

Pathogenic Bacteria ◽

Metabolic Modeling ◽

Metabolic Model ◽

Metabolic Adaptation ◽

Ecological Niches ◽

Plant Colonization ◽

Phenotypic Data ◽

Plant Pathogenic Bacteria ◽

Metabolic Versatility

Understanding plant–microbe interactions is crucial for improving plants’ productivity and protection. Constraint-based metabolic modeling is one of the possible ways to investigate the bacterial adaptation to different ecological niches and may give insights into the metabolic versatility of plant pathogenic bacteria. We reconstructed a raw metabolic model of the emerging plant pathogenic bacterium Pectobacterium parmentieri SCC3193 with the use of KBase. The model was curated by using inParanoind and phenotypic data generated with the use of the OmniLog system. Metabolic modeling was performed through COBRApy Toolbox v. 0.10.1. The curated metabolic model of P. parmentieri SCC3193 is highly reliable, as in silico obtained results overlapped up to 91% with experimental data on carbon utilization phenotypes. By mean of flux balance analysis (FBA), we predicted the metabolic adaptation of P. parmentieri SCC3193 to two different ecological niches, relevant for the persistence and plant colonization by this bacterium: soil and the rhizosphere. We performed in silico gene deletions to predict the set of essential core genes for this bacterium to grow in such environments. We anticipate that our metabolic model will be a valuable element for defining a set of metabolic targets to control infection and spreading of this plant pathogen.

Download Full-text

Dynamics of fungal pathogens in host plant tissues

Canadian Journal of Botany ◽

10.1139/b95-388 ◽

1995 ◽

Vol 73 (S1) ◽

pp. 1275-1283 ◽

Cited By ~ 4

Author(s):

Shigehito Takenaka

Keyword(s):

Host Plant ◽

Species Interactions ◽

Fungal Biomass ◽

Quantitative Methods ◽

Plant Pathogens ◽

Pathogenic Fungi ◽

Molecular Methods ◽

Plant Colonization ◽

Fungal Colonization ◽

Plant Tissues

To develop efficient control measures against fungal plant pathogens, the dynamics of host plant colonization during disease development and the interactions among fungi within host plant tissues need to be clarified. These studies require accurate quantitative estimation of specific fungal biomass in plant tissues. This has been approached by direct-microscopic methods, cultural methods, chemical determinations of fungal components, serological methods, and molecular methods. Among these methods, serological and molecular methods provide rapid, specific, and sensitive quantitative measures of fungal biomass in host plant tissues. Therefore, studies on fungal dynamics of host plant colonization using these two methods are presented. Some examples of species interactions among pathogenic fungi within host plants, such as synergism and competition, are reviewed and the usefulness of serological and molecular methods for studies on these interactions is presented. These quantitative methods will provide helpful information for understanding the ecology of plant pathogenic fungi, such as the dynamics of host plant colonization and species interactions. Key words: quantitative methods, fungal biomass, ELISA, PCR, fungal colonization, species interaction.

Download Full-text

Convergence of soil microbial properties after plant colonization of an experimental plant diversity gradient

BMC Ecology ◽

10.1186/s12898-016-0073-0 ◽

2016 ◽

Vol 16 (1) ◽

Cited By ~ 12

Author(s):

Katja Steinauer ◽

Britta Jensen ◽

Tanja Strecker ◽

Enrica de Luca ◽

Stefan Scheu ◽

...

Keyword(s):

Plant Diversity ◽

Plant Colonization ◽

Experimental Plant ◽

Microbial Properties ◽

Soil Microbial ◽

Diversity Gradient ◽

Soil Microbial Properties

Download Full-text

Safe-Site Effects on Rhizosphere Bacterial Communities in a High-Altitude Alpine Environment

BioMed Research International ◽

10.1155/2014/480170 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 9

Author(s):

Sonia Ciccazzo ◽

Alfonso Esposito ◽

Eleonora Rolli ◽

Stefan Zerbe ◽

Daniele Daffonchio ◽

...

Keyword(s):

High Altitude ◽

Developmental Stage ◽

Bacterial Communities ◽

Developmental Stages ◽

Gene Diversity ◽

Intergenic Spacer ◽

Intermediate Stage ◽

Plant Colonization ◽

Early Developmental Stage ◽

Rrna Gene

The rhizosphere effect on bacterial communities associated with three floristic communities (RW, FI, and M sites) which differed for the developmental stages was studied in a high-altitude alpine ecosystem. RW site was an early developmental stage, FI was an intermediate stage, M was a later more matured stage. The N and C contents in the soils confirmed a different developmental stage with a kind of gradient from the unvegetated bare soil (BS) site through RW, FI up to M site. The floristic communities were composed of 21 pioneer plants belonging to 14 species. Automated ribosomal intergenic spacer analysis showed different bacterial genetic structures per each floristic consortium which differed also from the BS site. When plants of the same species occurred within the same site, almost all their bacterial communities clustered together exhibiting a plant species effect. Unifrac significance value (P<0.05) on 16S rRNA gene diversity revealed significant differences (P<0.05) between BS site and the vegetated sites with a weak similarity to the RW site. The intermediate plant colonization stage FI did not differ significantly from the RW and the M vegetated sites. These results pointed out the effect of different floristic communities rhizospheres on their soil bacterial communities.

Download Full-text

Catalase released from beneficial and plant-pathogenic pseudomonads by water and chloroform treatments

Canadian Journal of Microbiology ◽

10.1139/m94-100 ◽

1994 ◽

Vol 40 (8) ◽

pp. 630-636

Author(s):

J. I. Pounder ◽

A. J. Anderson

Keyword(s):

Hydrogen Peroxide ◽

Superoxide Dismutase ◽

Water Treatment ◽

Pseudomonas Syringae ◽

Small Proportion ◽

Plant Colonization ◽

Periplasmic Proteins ◽

Specific Activities ◽

Leaf Pathogen ◽

Glucose 6 Phosphate Dehydrogenase

Survival of pseudomonads during plant colonization may involve bacterial catalases to degrade the hydrogen peroxide produced by the plant. The specific activities of catalases in lysates from two saprophytic isolates of Pseudomonas putida and Pseudomonas fluorescens and three races of Pseudomonas syringae pv. glycinea were similar. To explore the location of the bacterial catalases, cells of the pathogenic and saprophytic pseudomonads were treated with chloroform, which is reported to release periplasmic proteins. Although catalase was released by chloroform treatment, the cytoplasmic enzymes isocitrate dehydrogenase, superoxide dismutase, and glucose-6-phosphate dehydrogenase were also detected. These proteins may have come from lysis of a small proportion of the cells rather than the periplasm. Water treatment of cells also released amounts of protein similar to those derived from chloroform treatment. Similar responses were found from both pathogenic and saprophytic strains. The release of catalase and proteins from the leaf pathogen P. syringae pv. glycinea race 0 and the root-associated saprophyte P. putida decreased as the cultures aged. With P. putida and P. syringae pv. glycinea race 0, the single isozyme of catalase released by water and chloroform treatment also was detected in lysates. Additional catalase isozymes were present in lysates as the cultures aged.Key words: periplasmic proteins, survival.

Download Full-text