Bacillus subtilis and Bacillus velezensis population dynamics and quantification of spores after inoculation on ornamental plants

Bacillus subtilis and Bacillus velezensis are used in organic agriculture as an alternative to chemical pesticides to fight against phytopathogen organisms. These Gram-positive soil-dwelling bacteria are able to resist harsh conditions and survive by differentiating into endospores. Few studies have examined how bacterial populations change on plants over time, and whether they remain active or enter a dormant state. Nonetheless, these characteristics are strikingly important to determine the usage of B. subtilis and B. velezensis and their efficacy in environmental conditions. Here, we investigated the population dynamics of B. subtilis NCIB3610 and B. velezensis QST713 when applied as spores on different ornamental plants. We report that on all the plants studied (Echinacea purpurea ‘Salsa red’, Echinacea purpurea ‘Fatal attraction’, and Lavandula angustifolia ‘Hidecote blue’), spores rapidly germinated and colonized the rhizoplane, maintaining a relatively low proportion of spores in the population over time, whereas the bacterial population on the leaves rapidly declined. Bacteria in the surrounding soil did not germinate and persisted as spores. Taken together, these results suggest that only cells found at the rhizosphere remain metabolically active to allow the formation of a lasting relationship with the plant, making possible beneficial effects from the inoculated bacteria.

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Analysis of 220 Years of Floodplain Population Dynamics in the US at Different Spatial Scales

Water ◽

10.3390/w13020141 ◽

2021 ◽

Vol 13 (2) ◽

pp. 141

Author(s):

Firoza Akhter ◽

Maurizio Mazzoleni ◽

Luigia Brandimarte

Keyword(s):

Population Dynamics ◽

Large Scale ◽

Spatial Scales ◽

National Level ◽

State Level ◽

Economic Activities ◽

Protection Measures ◽

Management Planning ◽

The Us ◽

Over Time

In this study, we explore the long-term trends of floodplain population dynamics at different spatial scales in the contiguous United States (U.S.). We exploit different types of datasets from 1790–2010—i.e., decadal spatial distribution for the population density in the US, global floodplains dataset, large-scale data of flood occurrence and damage, and structural and nonstructural flood protection measures for the US. At the national level, we found that the population initially settled down within the floodplains and then spread across its territory over time. At the state level, we observed that flood damages and national protection measures might have contributed to a learning effect, which in turn, shaped the floodplain population dynamics over time. Finally, at the county level, other socio-economic factors such as local flood insurances, economic activities, and socio-political context may predominantly influence the dynamics. Our study shows that different influencing factors affect floodplain population dynamics at different spatial scales. These facts are crucial for a reliable development and implementation of flood risk management planning.

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Combined Application of Rhizosphere Bacteria with Endophytic Bacteria Suppresses Root Diseases and Increases Productivity of Black Pepper (Piper nigrum L.)

Agriculture ◽

10.3390/agriculture11010015 ◽

2020 ◽

Vol 11 (1) ◽

pp. 15

Author(s):

Sy Dinh Nguyen ◽

Thi Huyen Trang Trinh ◽

Trung Dzung Tran ◽

Tinh Van Nguyen ◽

Hoang Van Chuyen ◽

...

Keyword(s):

Bacillus Subtilis ◽

Endophytic Bacteria ◽

Growth Promotion ◽

Black Pepper ◽

Rhizosphere Bacteria ◽

Growth And Yield ◽

Piper Nigrum ◽

Bacillus Velezensis ◽

Root Knot Nematode ◽

Central Highland

Black pepper (Piper nigrum L.) is one of the most important crops and global demand continues to increase, giving it a high export value. However, black pepper cultivation has been seriously affected by a number of pathogenic diseases. Among them, “quick wilt” caused by Phytophthora sp., “slow decline” caused by Fusarium sp., and root-knot nematode Meloidogyne sp. have a serious negative effect on black pepper growth and productivity. There have been different chemical and biological methods applied to control these diseases, but their effectiveness has been limited. The aim of this research was to evaluate different combinations of rhizosphere bacteria and endophytic bacteria isolated from black pepper farms in the Central Highland of Vietnam for their ability to suppress pathogens and promote black pepper growth and yield. Formula 6, containing the strains Bacillus velezensis KN12, Bacillus amyloliquefaciens DL1, Bacillus velezensis DS29, Bacillus subtilis BH15, Bacillus subtilis V1.21 and Bacillus cereus CS30 exhibited the largest effect against Phytophthora and Fusarium in the soil and in the roots of black pepper. These bio-products also increased chlorophyll a and b contents, which led to a 1.5-fold increase of the photosynthetic intensity than the control formula and a 4.5% increase in the peppercorn yield (3.45 vs. 3.30 tons per hectare for the control). Our results suggest that the application of rhizosphere and endophytic bacteria is a promising method for disease control and growth-promotion of black pepper.

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The influence of microhabitat on the population dynamics of four herbaceous species in a semiarid area of northeastern Brazil

Brazilian Journal of Biology ◽

10.1590/1519-6984.10014 ◽

2016 ◽

Vol 76 (1) ◽

pp. 45-54 ◽

Cited By ~ 2

Author(s):

K. A. Silva ◽

J. M. F. F. Santos ◽

J. R. Andrade ◽

E. N. Lima ◽

U. P. Albuquerque ◽

...

Keyword(s):

Population Dynamics ◽

Population Size ◽

Mortality Rates ◽

Dry Forest ◽

Northeastern Brazil ◽

Annual Rainfall ◽

Herbaceous Species ◽

Forest Fragment ◽

Experimental Station ◽

Over Time

Abstract Variation in annual rainfall is considered the most important factor influencing population dynamics in dry environments. However, different factors may control population dynamics in different microhabitats. This study recognizes that microhabitat variation may attenuate the influence of climatic seasonality on the population dynamics of herbaceous species in dry forest (Caatinga) areas of Brazil. We evaluated the influence of three microhabitats (flat, rocky and riparian) on the population dynamics of four herbaceous species (Delilia biflora, Commelina obliqua, Phaseolus peduncularis and Euphorbia heterophylla) in a Caatinga (dry forest) fragment at the Experimental Station of the Agronomic Research Institute of Pernambuco in Brazil, over a period of three years. D. biflora, C. obliqua and P. peduncularis were found in all microhabitats, but they were present at low densities in the riparian microhabitat. There was no record of E. heterophylla in the riparian microhabitat. Population size, mortality rates and natality rates varied over time in each microhabitat. This study indicates that different establishment conditions influenced the population size and occurrence of the four species, and it confirms that microhabitat can attenuate the effect of drought stress on mortality during the dry season, but the strength of this attenuator role may vary with time and species.

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The dynamics of questing ticks collected for 164 consecutive months off the vegetation of two landscape zones in the Kruger National Park (1988–2002). Part II. Rhipicephalus appendiculatus and Rhipicephalus zambeziensis

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v78i1.233 ◽

2011 ◽

Vol 78 (1) ◽

Cited By ~ 9

Author(s):

Arthur M. Spickett ◽

Gordon J. Gallivan ◽

Ivan G. Horak

Keyword(s):

Population Dynamics ◽

Relative Humidity ◽

National Park ◽

Rhipicephalus Appendiculatus ◽

Kruger National Park ◽

Large Herbivore ◽

Questing Ticks ◽

Over Time

The study aimed to assess the long-term population dynamics of questing Rhipicephalus appendiculatus and Rhipicephalus zambeziensis in two landscape zones of the Kruger National Park (KNP). Ticks were collected by dragging the vegetation monthly in three habitats (grassland, woodland and gully) at two sites in the KNP (Nhlowa Road and Skukuza) from August 1988 to March 2002. Larvae were the most commonly collected stage of both species. More R. appendiculatus were collected at Nhlowa Road than at Skukuza, with larvae being most abundant from May to August, while nymphs were most abundant from August to December. Larvae were most commonly collected in the gullies from 1991 to 1994, but in the grassland and woodland habitats from 1998 onwards. Nymphs were most commonly collected in the grassland and woodland. More R. zambeziensis were collected at Skukuza than at Nhlowa Road, with larvae being most abundant from May to September, while nymphs were most abundant from August to November. Larvae and nymphs were most commonly collected in the woodland and gullies and least commonly in the grassland (p < 0.01). The lowest numbers of R. appendiculatus were collected in the mid-1990s after the 1991/1992 drought. Rhipicephalus zambeziensis numbers declined after 1991 and even further after 1998, dropping to their lowest levels during 2002. The changes in numbers of these two species reflected changes in rainfall and the populations of several of their large herbivore hosts, as well as differences in the relative humidity between the two sites over time.

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Cultivar Contributes to the Beneficial Effects of Bacillus subtilis PTA-271 and Trichoderma atroviride SC1 to Protect Grapevine Against Neofusicoccum parvum

Frontiers in Microbiology ◽

10.3389/fmicb.2021.726132 ◽

2021 ◽

Vol 12 ◽

Author(s):

Catarina Leal ◽

Nicolas Richet ◽

Jean-François Guise ◽

David Gramaje ◽

Josep Armengol ◽

...

Keyword(s):

Bacillus Subtilis ◽

Trichoderma Atroviride ◽

In Planta ◽

Neofusicoccum Parvum ◽

Beneficial Effects ◽

Grapevine Trunk Diseases ◽

Mutual Antagonism ◽

Direct Benefits ◽

Botryosphaeria Dieback

Grapevine trunk diseases (GTDs) are a big threat for global viticulture. Without effective chemicals, biocontrol strategies are developed as alternatives to better cope with environmental concerns. A combination of biological control agents (BCAs) could even improve sustainable disease management through complementary ways of protection. In this study, we evaluated the combination of Bacillus subtilis (Bs) PTA-271 and Trichoderma atroviride (Ta) SC1 for the protection of Chardonnay and Tempranillo rootlings against Neofusicoccum parvum Bt67, an aggressive pathogen associated to Botryosphaeria dieback (BD). Indirect benefits offered by each BCA and their combination were then characterized in planta, as well as their direct benefits in vitro. Results provide evidence that (1) the cultivar contributes to the beneficial effects of Bs PTA-271 and Ta SC1 against N. parvum, and that (2) the in vitro BCA mutual antagonism switches to the strongest fungistatic effect toward Np-Bt67 in a three-way confrontation test. We also report for the first time the beneficial potential of a combination of BCA against Np-Bt67 especially in Tempranillo. Our findings highlight a common feature for both cultivars: salicylic acid (SA)-dependent defenses were strongly decreased in plants protected by the BCA, in contrast with symptomatic ones. We thus suggest that (1) the high basal expression of SA-dependent defenses in Tempranillo explains its highest susceptibility to N. parvum, and that (2) the cultivar-specific responses to the beneficial Bs PTA-271 and Ta SC1 remain to be further investigated.

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Seed Banks Alter the Rate and Direction of Molecular Evolution in Bacillus subtilis

10.1101/2021.10.05.463161 ◽

2021 ◽

Author(s):

William R. Shoemaker ◽

Evgeniya Polezhaeva ◽

Kenzie B. Givens ◽

Jay T. Lennon

Keyword(s):

Bacillus Subtilis ◽

Molecular Evolution ◽

Seed Bank ◽

Negative Selection ◽

Evolutionary Dynamics ◽

Genetic Manipulation ◽

Seed Banks ◽

Rate Of Molecular Evolution ◽

Over Time ◽

Growth And Reproduction

Fluctuations in the availability of resources constrains the growth and reproduction of individuals, which in turn effects the evolution of their respective populations. Many organisms are able to respond to fluctuations by entering a reversible state of reduced metabolic activity, a phenomenon known as dormancy. This pool of dormant individuals (i.e., a seed bank) does not reproduce and is expected to act as an evolutionary buffer, though it is difficult to observe this effect directly over an extended evolutionary timescale. Through genetic manipulation, we analyze the molecular evolutionary dynamics of Bacillus subtilis populations in the presence and absence of a seed bank over 700 days. We find that the ability to enter a dormant state increases the accumulation of genetic diversity over time and alters the trajectory of mutations, findings that are recapitulated using simulations based on a simple mathematical model. While the ability to form a seed bank does not alter the degree of negative selection, we find that it consistently alters the direction of molecular evolution across genes. Together, these results show that the ability to form a seed bank affects the direction and rate of molecular evolution over an extended evolutionary timescale.

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First Report of Powdery Mildew, Caused by Erysiphe cichoracearum, on Coneflowers

Plant Disease ◽

10.1094/pdis.1999.83.7.694b ◽

1999 ◽

Vol 83 (7) ◽

pp. 694-694 ◽

Cited By ~ 2

Author(s):

P. L. Sholberg ◽

J. H. Ginns ◽

T. S. C. Li

Keyword(s):

Powdery Mildew ◽

Ornamental Plants ◽

Echinacea Purpurea ◽

The United States ◽

Plant Diseases ◽

Conidial Suspension ◽

Decay Fungi ◽

Erysiphe Cichoracearum ◽

Epidermal Surface ◽

Medicinal Properties

Purple coneflowers (Echinacea purpurea) are grown in North America and Europe for their medicinal properties and as ornamental plants. In September 1997 and again in 1998, a previously undescribed disease was noticed on fully grown coneflower plants in Summerland and Oliver, British Columbia. Mycelia were observed on stems, foliage, and flowers, and distinct dark red to black, round (approximately 5 mm in diameter) lesions were observed on the flower petals. The disease appeared similar to powdery mildews that have been reported on numerous genera of the Asteraceae. Samples of the diseased tissue were examined and the salient features of the fungus on two specimens were determined: cleistothecia infrequent, subglobose or flattened on the side next to the leaf surface, 121 to 209 μm in diameter; epidermal (surface) cells 20 μm in diameter; appendages hyphoid, 5 μm in diameter, up to 200 μm long; asci, 10 to 19 in each cleistothecium, broadly ellipsoid, 47 to 85 × 28 to 37 μm with a short stalk, about 8 to 13 μm long and 8 μm in diameter; ascospores, immature, two per ascus, ellipsoid to broadly ellipsoid, 17 to 25 × 11 to 13 μm, thin walled, hyaline, and smooth; conidia oblong with sides slightly convex and apices truncate, 27 to 40 × 14 to 20 μm, walls hyaline, thin, smooth. Based on the occurrence of asci that contained two ascospores and the hyphoid appendages on the cleistothecia we concluded that the fungus was Erysiphe cichoracearum DC. Damage due to this disease was minimal in 1997 and 1998 because it developed very late in the growing season and occurred sporadically within the plantings. In order to complete Koch's postulates, Echinacea purpurea plants grown in the greenhouse were inoculated with a conidial suspension (105 to 106 conidia per ml) from field-infected plants. Powdery mildew first appeared 3 months later, eventually infecting leaves and stems of 12 of 49 inoculated plants. It was distinctly white and in discrete patches on leaves, compared with coalescing dark brown areas on the stems. Microscopic examination of the conidia confirmed that they were E. cichoracearum. Although powdery mildew caused by E. cichoracearum has been widely reported on lettuce, safflower, and other cultivated and wild Compositae, we found no reference to it on Echinacea spp. in Canada (1,2), the U.S. (3), or elsewhere in the world (4). The specimens have been deposited in the National Mycological Herbarium of Canada (DAOM) with accession numbers 225933 and 225934 for Oliver and Summerland, B.C., respectively. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) I. L. Conners. 1967. An annotated index of plant diseases in Canada and fungi recorded on plants in Alaska, Canada, and Greenland. Canada Dept. of Agric. Pub. 1251. (3) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN. (4) J. Ginns. 1986. Compendium of plant disease and decay fungi in Canada, 1960-1980. Agriculture Canada Pub. 1813.

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Death and population dynamics affect mutation rate estimates and evolvability under stress in bacteria

10.1101/224675 ◽

2017 ◽

Author(s):

Antoine Frénoy ◽

Sebastian Bonhoeffer

Keyword(s):

Population Dynamics ◽

Mutation Rate ◽

Death Rate ◽

Mutation Rates ◽

Resistance Mutations ◽

Bacterial Populations ◽

Plasmid Segregation ◽

Genome Wide ◽

Response To Stress ◽

Induced Mutagenesis

AbstractThe stress-induced mutagenesis paradigm postulates that in response to stress, bacteria increase their genome-wide mutation rate, in turn increasing the chances that a descendant is able to withstand the stress. This has implications for antibiotic treatment: exposure to sub-inhibitory doses of antibiotics has been reported to increase bacterial mutation rates, and thus probably the rate at which resistance mutations appear and lead to treatment failure.Measuring mutation rates under stress, however, is problematic, because existing methods assume there is no death. Yet sub-inhibitory stress levels may induce a substantial death rate. Death events need to be compensated by extra replication to reach a given population size, thus giving more opportunities to acquire mutations. We show that ignoring death leads to a systematic overestimation of mutation rates under stress.We developed a system using plasmid segregation to measure death and growth rates simultaneously in bacterial populations. We use it to replicate classical experiments reporting antibiotic-induced mutagenesis. We found that a substantial death rate occurs at the tested sub-inhibitory concentrations, and taking this death into account lowers and sometimes removes the signal for stress-induced mutagenesis. Moreover even when antibiotics increase mutation rate, sub-inhibitory treatments do not increase genetic diversity and evolvability, again because of effects of the antibiotics on population dynamics.Beside showing that population dynamic is a crucial but neglected parameter affecting evolvability, we provide better experimental and computational tools to study evolvability under stress, leading to a re-assessment of the magnitude and significance of the stress-induced mutagenesis paradigm.

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Population Dynamics and Tree Damage of the Invasive Chestnut Gall Wasp, Dryocosmus kuriphilus, in Its Southernmost European Distributional Range

Insects ◽

10.3390/insects12100900 ◽

2021 ◽

Vol 12 (10) ◽

pp. 900

Author(s):

Javier Quinto ◽

María Eva Wong ◽

Juan Ramón Boyero ◽

José Miguel Vela ◽

Martin Aguirrebengoa

Keyword(s):

Population Dynamics ◽

Control Mechanisms ◽

Gall Wasp ◽

Local Conditions ◽

Tree Damage ◽

Dryocosmus Kuriphilus ◽

Distributional Range ◽

The Status ◽

Spatio Temporal ◽

Over Time

The invasive chestnut gall wasp (CGW), Dryocosmus kuriphilus, the worst pest of chestnut cultivation, has spread worryingly throughout Europe in less than 20 years. Despite the great concern around this pest, little is known about the status in its southernmost distribution in continental Europe. We assessed spatio-temporal patterns in the population dynamics, phenology and tree damage caused by CGW in southern Spain. Likewise, the relationship between these variables and thermal trends was evaluated. We found strong variation in the population dynamics and flight phenology among localities and over time, which were highly influenced by changes in thermal regimes. Specifically, warmer localities and vegetative periods promoted higher population densities, a partial increase in the survival of immature stages, and advanced flight activity. Moreover, tree damage evolved differently over time in each locality, which suggests that local conditions may determine differences in damage evolution. Our findings evidence that great spatio-temporal variability in the CGW populations takes place across invaded areas in its southernmost European distributional range. Although control mechanisms have been introduced, implementation of further control and management measures are critical to cope with this main threat for the chestnut industry and to prevent its spread to nearing chestnut-producing areas.

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