Nutrient-induced spore germination of aBacillus amyloliquefaciensbiocontrol agent on wheat spikes

Abstract

Aims: In this study, we investigated the feasibility of applying nutrient germinants to plant surfaces to stimulate the spore germination of the plant disease biocontrol agent Bacillus amyloliquefaciens strain TrigoCor. Methods and Results: Using the terbium chloride assay and phase-contrast microscopy, we screened potential germinants of TrigoCor spores and found that a combination of D-glucose, D-fructose and potassium chloride (GFK), in addition to either L-asparagine (Asn-GFK) or L-alanine (Ala-GFK), induced maximal levels of TrigoCor spore germination in vitro. The germinant mixture Asn-GFK was also able to significantly stimulate Bacillus spore germination on wheat surfaces. Conclusions: The successful in vivo stimulation of Bacillus spore germination suggests that nutrient-induced spore germination on plant surfaces is a feasible strategy for improving Bacillus biocontrol. Significance and Impact of the Study: One of the challenges of applying Bacillus biological control agents to aboveground plant parts is that Bacillus cells transition to a metabolically dormant spore state on plant surfaces, making them unable to prevent subsequent pathogen attacks. This study demonstrates that using nutrients to stimulate Bacillus spore germination in vivo is a promising option for improving disease control and should be pursued further.

Effect of Selenium on Control of Postharvest Gray Mold of Tomato Fruit and the Possible Mechanisms Involved

“…Mineral nutrients has important benefits for the growth and development of many organisms, and are essential factors in biotic plant interactions while influencing plant health ( Ahn et al, 2005 ; Datnoff et al, 2007 ; Cabot et al, 2013 ; Crane et al, 2014 ). The most recent information regarding the effect of nutrients on disease resistance and tolerance to pathogens has been reported by others ( Boyd, 2007 ; Fones et al, 2010 ; Hörger et al, 2013 ).…”

Evaluation of different strategies for efficient sporulation and germination of the MICP bacterium Lysinibacillus sphaericus strain MB284 (ATCC 13805)

“…Dormant endospores are able to sense their surrounding environment, and whenever the environment becomes favorable and suitable for their growth, they break dormancy and initiate germination and outgrowth processes to regain the physiology and metabolic functions of vegetative cells [7, 9, 10, 12]. The length of the lag phase during the germination process depends on the type of species and environmental condition and can vary from a couple of minutes to more than a couple of days [8].…”

“…In addition to adding nutrients, non-nutrient agents such as dodecylamine, CaDPA, L-valine, L-alanine, L-proline, L-asparagine, and surfactants can trigger endospore germination [12, 9]. Although the lag phase for germination of the strain MB284 was not long in the absence of aiding agents, the impact of L-valine and dodecylamine on the growth curve was investigated in this study (Figure 4).…”

“…While vegetative cells of non-spore-forming bacteria cannot survive in these inhospitable conditions, some genera of bacteria, including Bacillus and Clostridium , under such harsh conditions, can generate inactive, dormant, and multi-layered endospores. The spore-forming organisms are able to preserve their genetic content and overcome unfavorable mechanical, physical, and chemical conditions [5, 6] including extreme starvation and temperature, freezing and thawing, desiccation, high hydrostatic pressure, depletion of nutrients, and exposure to solar, ultraviolet, ϒ-radiations, organic solvents, oxidizing agents, alkaline, acids, toxic and corrosive chemicals and physical abrasion [4, 7, 8, 9, 10, 11, 12]. Although the process of sporulation is complex and largely unknown for many spore-forming species [13], studies on spores have revealed common defense mechanisms, such as coating layers, that exhibit low permeabilities and are considered the first defense lines against thermal shock [10], toxic chemicals, and enzymatic attacks [14, 10, 12].…”

Synergistic Effect of Melatonin and Selenium Improves Resistance to Postharvest Gray Mold Disease of Tomato Fruit

“…Mineral nutrition has important benefits for plant growth and development as well as has impacts on the plant disease tolerance or resistance, and is recognized as an important component of disease control practices ( Datnoff et al, 2007 ; Cabot et al, 2013 ; Crane et al, 2014 ; Brown et al, 2021 ). The recent information regarding the effect of nutrition on disease tolerance or resistance has been reported by others ( Boyd, 2007 ; Dordas, 2008 ; Fones et al, 2010 ; Shi et al, 2011 ; Yao et al, 2012 ; Fones and Preston, 2013 ; Hörger et al, 2013 ; Yaganza et al, 2014 ; Vilaplana et al, 2018 ; Brown et al, 2021 ).…”