Methods and compositions for improving plant traits
Inventors
Temme, Karsten • Tamsir, Alvin • BLOCH, Sarah • CLARK, Rosemary • TUNG, Emily • Hammill, Kevin • Higgins, Douglas • Davis-Richardson, Austin
Assignees
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Publication Number
US-12686650-B2
Publication Date
2026-07-21
Expiration Date
Abstract
Methods and systems are provided for generating and utilizing a bacterial composition that comprises at least one genetically engineered bacterial strain that fixes atmospheric nitrogen in an agricultural system that has been fertilized with more than 20 lbs of Nitrogen per acre.
Core Innovation
The disclosed invention concerns engineered diazotrophic bacteria for non-leguminous plants to increase available nitrogen in a field. The bacteria maintain atmospheric nitrogen fixation and transfer fixed nitrogen despite the presence of exogenous fertilizer. Genetic modifications alter nitrogen-fixation and assimilation regulatory networks, comprising a complete or partial nifL deletion and a constitutive promoter operably linked to a nifA gene. Bacterial performance is defined by the product of field-condition colonization ability and nitrogen produced per bacterial cell per hour.
The disclosed bacteria sustain nitrogen fixation, exhibit derepressed nitrogenase activity, and increase ammonia excretion and in-planta nif expression across diverse soil types. In greenhouse and field evaluations, the bacteria contribute measurable atmospheric nitrogen to plants, resulting in enhanced leaf area and crop yield gains under low-nitrogen regimes. The subject matter further encompasses non-leguminous plants colonized by the bacteria and compositions combining the bacteria with plant seeds.
Claims Coverage
The independent claims cover a field method, a colonized non-leguminous plant, and a seed composition, establishing three inventive features.
Field application of engineered diazotrophic bacteria
A method applies a plurality of engineered diazotrophic bacteria to a non-leguminous plant in a field to increase available nitrogen. The bacteria meet criteria for field-condition colonization ability and fixed nitrogen produced per bacterial cell per hour, and comprise a complete or partial nifL deletion and a constitutive promoter operably linked to a nifA gene.
Non-leguminous plant colonized by engineered diazotrophic bacteria
A non-leguminous plant is colonized with engineered diazotrophic bacteria meeting specified criteria for field-condition colonization ability and fixed nitrogen produced per bacterial cell per hour. The bacteria comprise a complete or partial nifL deletion and an inserted constitutive promoter operably linked to a nifA gene.
Composition of engineered diazotrophic bacteria and plant seed
A composition comprises engineered diazotrophic bacteria and a non-leguminous plant seed capable of providing at least one pound of nitrogen per acre per season to a plant produced from the seed in a field. The bacteria meet specified field-condition colonization and nitrogen-production criteria and comprise a complete or partial nifL deletion and a constitutive promoter operably linked to a nifA gene.
The independent claims cover applying engineered diazotrophic bacteria in a field, a non-leguminous plant colonized by the bacteria, and a bacterial seed composition, each defined by specified colonization and nitrogen-production performance and genetic variations involving nifL and nifA.
Stated Advantages
The claimed method increases available nitrogen for a non-leguminous plant in a field.
The engineered diazotrophic bacteria maintain atmospheric nitrogen fixation and transfer fixed nitrogen to non-leguminous crops despite the presence of exogenous fertilizer.
The description summary reports increased ammonia excretion and measurable atmospheric nitrogen contributions to corn, including approximately 20% of above-ground corn nitrogen from PBC6.94 in a greenhouse study.
The bacterial and seed composition provides at least one pound of nitrogen per acre per season to a non-leguminous plant produced from the seed in a field.
Field trials report yield gains under low-nitrogen regimes and positive trial win rates for selected microbes.
Plants receiving microbial fixed nitrogen exhibit increased leaf area.
Documented Applications
Field application of engineered diazotrophic bacteria to non-leguminous plants to increase available nitrogen, identifying corn, rice, wheat, barley, sorghum, millet, oat, rye, triticale, and Setaria as crop options.
Microbial compositions combining engineered diazotrophic bacteria with non-leguminous plant seeds, including seed, seedling, in-furrow, and plant applications to provide nitrogen to plants produced in a field.
Colonization of non-leguminous plants by engineered diazotrophic bacteria.
Greenhouse and field evaluations involving corn to assess atmospheric nitrogen contribution and crop yield under low-nitrogen regimes.
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