Projects / Programmes
The role of social and genetic kin discrimination on B. subtilis interactions
| Code |
Science |
Field |
Subfield |
| 4.06.04 |
Biotechnical sciences |
Biotechnology |
Microbe biotechnology |
| Code |
Science |
Field |
| T490 |
Technological sciences |
Biotechnology |
| Code |
Science |
Field |
| 2.08 |
Engineering and Technology |
Environmental biotechnology
|
kin discrimination, swarming, Bacillus subtilis, Ralstonia solanacearum, plant bio-control
Researchers (18)
Organisations (2)
Abstract
Background: Recently, we investigated soil bacterium, Bacillus subtilis for its ability to discriminate kin from non-kin strains in the context of swarming and for the first time identified kin groups of B. subtilis among natural isolates. Plant root co-colonization of kin strain pairs resulted in a mixed strain biofilm, whereas non-kin strains fought for the colonization of the plant root and eventually only one strain prevailed. Problem description: The proposed project will focus on the study of ecological and evolutionary role of kin discrimination in the soil bacterium B. subtilis, which is unexplored. This microorganism is extremely important industrially and agriculturally. It is often used in formulations for support of agricultural plants against pathogens. New guidelines for the development of plant support inoculants are aimed at combining different bacterial strains. It is unknown whether antagonistic behaviour of non-kin B. subtilis strains on plant roots will affect the plant health or/and protect the plant from being attacked by pathogens? The aim of the study: The project aims to determine the relationship between kin discrimination and territoriality, horizontal gene transfer, and ecosystem function. This knowledge will be then used to better understand biocontrol and plant growth promoting activity of B. subtilis. We will test these activities on agricultural plants (tomato, tobacco, plants) and in the presence/absence of plant deadly pathogen (Ralstonia) using mixtures of kin and non-kin strains. Comparative genomics on B. subtilis strains with a focus on how distribution of the antagonistic loci correlates with the phylogenetic distance, kin and pherotype groups will be performed. Originality of the results: B. subtilis is a soil organism with promising biocontrol activities. To this date it is unknown how antagonistic interactions between strains influence the plants. Given that antagonistic interactions between non-kin B. subtilis include the secretion of antimicrobial compounds these may protect the plant from pathogen invasion. Also, B. subtilis can protect the plant by competing for the plant root colonization area. These questions have never been addressed before in the context of kin discrimination and the results will give us valuable information about inter-species interactions that could potentially lead to a more efficient microbial biocontrol development and to commercialization of this research. Methods: Our laboratories have environmental Bacillus strains from two collections, namely soil and rhizosphere. We will construct fluorescently labeled strains in order to visualize biofilm formation, swarming and root colonization via fluorescent microscopy and perform bioinformatics analyses on genomes. Using total plant RNA we will analyse the expression of key genes involved in plant defence resulting from the interaction with different combinations of Bacillus strains. Results potential and relevancy: Only a few microbial species are able to distinguish kin from non-kin and we were the first to find this in B. subtilis. The proposed project is highly original and knowledge obtained will support 1) the development of new methods to follow kin and non-kin interactions using fluorescent microplate reader, fluorescent stereomicroscope and construction of fluorescently labeled strains; 2) deeper understanding of mechanisms behind kin and non-kin DNA exchange and the impact of this phenomenon on the ecology, sociality and evolution of this species; 3) improved understanding of inter-species interactions in the context of plant growth promotion and/or biocontrol activity. As the results will be new and exciting we will be able to publish our work in prestigious scientific journals reaffirming our group on a scientific map as a highly competent and productive in the field.
Significance for science
The project is based on the exceptional recent discovery of kin discrimination and years of research in the field of ecology and social interactions of Bacillus subtilis, which has for decades been an excellent model organism for basic research in biofilms, horizontal gene transfer, swarming, sporulation, and is of broad interest for many research groups and industry around the world. Furthermore, this soil and plant-root associated bacterium B. subtilis is useful for the health of the plants. The proposed research is linked to the interaction of B. subtilis with plants and the plant pathogen Ralstonia solanacearum. The projects combines ecological and molecular approaches to test five interesting scientific hypotheses that address the evolutionary importance of kin discrimination, its influence on horizontal gene transfer and bacterial territoriality and combines this knowledge with application of these bacteria in plant support. The hypotheses are of fundamental importance and have not yet been confirmed in the context of bacterial kin discrimination. For example, there is no evidence that kin discrimination protects the evolutionary stability of the cooperative properties which will be tested here. Research in the field of sociality of bacteria have already produced outstanding publications in journals with an impact factor of more than 9 (PNAS, Current Biology) by the project leader and the proposed project builds on these findings but also brings in completely new issues related to sociality, genomics, evolution of bacteria and plant protection. We will go an important step further by including agriculturally important plants (tomato, tobacco, potato) and deadly pathogen R. solanacearum in addition to Bacillus. We believe that this project will bring important new knowledge and publications in the most prestigious journals, invited lectures at foreign universities/conferences. This will be achieved through collaborations with partner institution NIB and groups lead by internationally recognized experts on plant biology and plant-pathogen interactions, prof. Ravnikar and prof. Gruden (receiver of Zois recognition award). They nicely complement the expertise of BF group in social microbiology and ecology of Bacillis, where prof. Mandič Mulec – an internationally expert in the field and the young productive team have already established their name. The collaboration of the two very successful groups (BF and NIB) provides a new dimension to the project proposal and will definitely increase both scientific and applicative relevance of the proposed research and scientific quality of the publications. The project will provide a number of joint publications (at least 5) in journals with high impact factor, which will bring novel discoveries, increase the international recognisability of research groups involved and will be an important incentive for the career of young, talented scientist and the proposed project leader dr. P. Štefanič.
Significance for the country
Healthy food in a healthy environment is one of the key priorities of EU innovative strategies and smart specialization of the Republic of Slovenia. The proposed project addresses fundamental scientific questions relevant for this priority with potential for solutions to support plant health by applying bacterial inoculants. Today, we cannot ignore the fact that the plant health and the environment are closely linked to the microorganisms. But in recent decades, the environment and agricultural land is burdened with heavy use of chemicals in the form of chemical plant protection agents and industrial fertilizers, thereby decreasing the quality of arable land and depleting bacterial microflora, which is essential for soil and plant health. By developing the environmentally friendly bio-inoculants we will decrease the usage of chemical fertilizers and dangerous pesticides in long term, which will have positive influence on health of our environment, human health and the quality of our food and for the establishment of higher levels of ecological farming. Bacterial inoculants are of interest for many companies, even pharmaceutical giants (i.e. Bayer Crop Science, AgroGreen, Novozyme, Arysta, Life Science, DuPont, Makhteshim Agan) but provide potential also for new, innovative and adaptable “start-ups” that may provide new jobs for young and educated. The market share of bacterial preparations for protection of plants is presently at ~ 2% of the total market value of chemical pesticides and potential for growth is high. The estimated value of biological agents in 2006 was estimated at $ 109 million but the conservative predictions for agricultural inoculants 2020 are $437 million. This indicates that the project has potential to bring new jobs and thus directly affect our society. We would like to note that the proposed research is also focused on finding solutions for the control of dangerous plant pathogen Ralstonia solanacearum, which causes an immense problem in agriculture, because it infects 250 different plant species and 50 plant families. R. solanacearum is one of the most destructive plant pathogens that can destroy up to~ 95% of the potato and/or tomato produce. Annual damage by this pathogen is estimated at $ 950 million. Friendly solutions decreasing these losses will have direct impact on economy. R. solanacearum is also ranked among biological weapons, which have the potential for application in agriculture. The development of bacterial inoculants that suppress this dangerous bacterium is an important research objective with a wide and direct relevance to the society and its health and safety.
Most important scientific results
Interim report,
final report
Most important socioeconomically and culturally relevant results
Interim report,
final report
