Pectin-Utilizing PGPR Strains for Rhizosphere Colonization
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Solution Overview
Problem
Current methods for promoting plant and animal growth and health using plant growth-promoting rhizobacteria (PGPR) are limited in efficacy, particularly in enhancing colonization and persistence of PGPR in the rhizosphere and improving growth and disease control.
Innovation Solution
The use of PGPR strains that express proteins associated with pectin metabolism, combined with pectin or pectin-related saccharides, to enhance colonization, persistence, and efficacy in promoting plant and animal growth and health.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PGPR strains are used for promoting plant growth and controlling diseases, then some level of growth promotion and disease control is achieved, but the efficacy is limited and colonization persistence in the rhizosphere is insufficient
Solution Approach 1:
The patent changes the biochemical parameters of PGPR strains by selecting bacteria that express specific proteins associated with pectin metabolism (such as pectinases, polygalacturonases, and pectin lyases). This parameter change enables the bacteria to utilize pectin as a carbon source, thereby enhancing their colonization ability, persistence, and overall efficacy in promoting plant growth and controlling diseases.
Solution Approach 2:
The patent introduces pectin or pectin-related saccharides as an intermediary substance that mediates between the PGPR strains and the plant system. This intermediary provides a sustained carbon source that enhances bacterial persistence in the rhizosphere, thereby improving the reliability and productivity of PGPR applications.
2Stability of the object's composition
If PGPR strains are applied to seeds or vegetative plant parts to colonize the root system, then colonization of the rhizosphere is achieved, but persistence and long-term efficacy are limited
Solution Approach 1:
The patent enables PGPR strains to utilize pectin naturally present in the rhizosphere environment as a carbon source through expression of pectin metabolism proteins. This self-service capability allows the bacteria to sustain themselves long-term in the rhizosphere without requiring continuous external supplementation, thereby enhancing persistence while maintaining stable colonization.
Solution Approach 2:
The patent changes the metabolic parameters of PGPR strains by selecting for bacteria expressing pectin-degrading enzymes. This parameter change enables the bacteria to exploit the abundant pectin substrate in the rhizosphere, thereby extending their persistence duration while maintaining stable root system colonization.
3Reliability
If multiple PGPR strains are used to enhance growth promotion and disease control, then broader efficacy is achieved, but the complexity of formulation and application increases
Solution Approach 1:
The patent extracts and utilizes the key functional characteristic of pectin metabolism capability from successful PGPR strains. By focusing on this specific trait (expression of pectin metabolism proteins), the patent simplifies the selection and formulation process while maintaining broad biological control effectiveness, thereby reducing formulation complexity without sacrificing reliability.
Data Source
AI summary
To understand the growth-promoting and disease-inhibiting activities of plant growth-promoting rhizobacteria (PGPR) strains, the genomes of 12 Bacillus subtilis group strains with PGPR activity were sequenced and analyzed. These B. subtilis strains exhibited high genomic diversity, whereas the genomes of B. amyloliquefaciens strains (a member of the B. subtilis group) are highly conserved. A pairwise BLASTp matrix revealed that gene family similarity among Bacillus genomes ranges from 32-90%, with 2,839 genes within the core genome of B. amyloliquefaciens subsp. plantarum (now B. velezensis). Comparative genomic analyses of B. amyloliquefaciens strains identified genes that are linked with biological control and colonization of roots and/or leaves, including 73 genes uniquely associated with subsp. plantarum (now B. velezensis) strains that have predicted functions related to signaling, transportation, secondary metabolite production, and carbon source utilization. Although B. amyloliquefaciens (now B. velezensis) strains contain gene clusters that encode many different secondary metabolites, only polyketide biosynthetic clusters that encode difficidin and macrolactin are conserved within this subspecies. To evaluate their role in plant pathogen biocontrol, genes involved in secondary metabolite biosynthesis were deleted in B. amyloliquefaciens (now B. velezensis) strain, revealing that difficidin expression is critical in reducing the severity of disease, caused by Xanthomonas axonopodis pv. vesicatoria in tomato plants. This Example defines genomic features of PGPR strains and links them with biocontrol activity and with host colonization.