Final Report Summary - ENDOPHYTES (Molecular basis of beneficial plant-endophyte interaction - sustainable agriculture from within)
In today’s world there is a growing need for food, feed and fuel. The search for a suite of strategies for sustainable production of biomass is of great scientific, technological and societal interest, and there is a pressing need to identify novel targets than can be manipulated for designing new strategies to enable sustainable crop production at higher intensities with limited water supply and to reduce our dependency on synthetic pesticides. Microbial endosymbionts, endophytes, represent alternative sources of biocontrol agents as they can enhance plant growth and tolerance to a variety of biotic and abiotic stresses. However, our knowledge of the interaction between plant host and endophytes is limited especially regarding how the interaction is initiated and maintained. This project aims to uncover the molecular bases of plant-endophyte interaction in the model plant Arabidopsis thaliana. The objectives are i) identify beneficial endophytes of A. thaliana; ii) identify the role of biofilm formation in plant-endophyte interaction; iii) identify host factors involved in plant-endophyte interaction.
To investigate the interaction between plant host and endophytes, a culture-dependent approach was undertaken and bacteria were isolated from surface-sterilized A. thaliana growing in a variety of soils. This non-exhaustive isolation yielded a total of 77 bacterial species belonging to the phyla actinobacteria, firmicutes and proteobacteria. An interesting finding was that regardless of the soil in which plants were grown, some species were consistently found associated with roots; the most common isolates included Methylobacteria and Microbacterium ginsengisoli, which suggests that these species are well adapted to life on and in plants.
The isolates were characterized for their ability to 1) synthesize the plant hormone indole-3-acetic acid; 2) Produce siderophores for iron uptake; 3) colonize seedlings; 4) Enhance biomass and lateral roots formation, since these traits are associated with growth promotion.
Several (35) of the isolated bacterial species produced plant growth promoting compounds such as siderophores and IAA and 16 species promoted plant growth and/or formation of lateral roots. These results suggest that A. thaliana in nature interacts with a range of beneficial microbes and that these microbes have the potential to be used in areas such as bio-fertilizer, bio-pesticides and bio-yield enhancers.
In a search for host factors involved in plant-endophyte interactions, we characterized a plant cell wall mutant (rwa2) with reduced acetylation of pectins and hemicelluloses. Plant cell wall acetylation can reduce the efficiency of bioethanol conversion and a techno-economic model predicts that a 20% reduction in cell wall acetylation would lead to a 10% reduction in bioethanol price. Thus a major goal in the field of plant biofuel research is to diminish the acetylation content in the cell wall of plants. We found that rwa2 had altered surface integrity and constitutive upregulation of selected defense pathways. The rwa2 mutant looks phenotypically normal, which suggest that cell wall acetylation can be altered for enhanced yield and biofuel production.
In conclusion, our work has identified a number of microbes with beneficial effects on A. thaliana with the potential to be used in the areas of bio-fertility, bio-pesticides and bio-yield enhancement for use in agriculture and industry. In addition, our work identified that plant cell acetylation plays a role for surface integrity and response to microbes.
To investigate the interaction between plant host and endophytes, a culture-dependent approach was undertaken and bacteria were isolated from surface-sterilized A. thaliana growing in a variety of soils. This non-exhaustive isolation yielded a total of 77 bacterial species belonging to the phyla actinobacteria, firmicutes and proteobacteria. An interesting finding was that regardless of the soil in which plants were grown, some species were consistently found associated with roots; the most common isolates included Methylobacteria and Microbacterium ginsengisoli, which suggests that these species are well adapted to life on and in plants.
The isolates were characterized for their ability to 1) synthesize the plant hormone indole-3-acetic acid; 2) Produce siderophores for iron uptake; 3) colonize seedlings; 4) Enhance biomass and lateral roots formation, since these traits are associated with growth promotion.
Several (35) of the isolated bacterial species produced plant growth promoting compounds such as siderophores and IAA and 16 species promoted plant growth and/or formation of lateral roots. These results suggest that A. thaliana in nature interacts with a range of beneficial microbes and that these microbes have the potential to be used in areas such as bio-fertilizer, bio-pesticides and bio-yield enhancers.
In a search for host factors involved in plant-endophyte interactions, we characterized a plant cell wall mutant (rwa2) with reduced acetylation of pectins and hemicelluloses. Plant cell wall acetylation can reduce the efficiency of bioethanol conversion and a techno-economic model predicts that a 20% reduction in cell wall acetylation would lead to a 10% reduction in bioethanol price. Thus a major goal in the field of plant biofuel research is to diminish the acetylation content in the cell wall of plants. We found that rwa2 had altered surface integrity and constitutive upregulation of selected defense pathways. The rwa2 mutant looks phenotypically normal, which suggest that cell wall acetylation can be altered for enhanced yield and biofuel production.
In conclusion, our work has identified a number of microbes with beneficial effects on A. thaliana with the potential to be used in the areas of bio-fertility, bio-pesticides and bio-yield enhancement for use in agriculture and industry. In addition, our work identified that plant cell acetylation plays a role for surface integrity and response to microbes.