Abstract: A method for promoting the health of a plant comprises administering malic acid to the plant or the soil in an amount effective to recruit plant growth promoting rhizobacteria (PGPR) to the plant. Administration of malic acid promotes biofilm formation of PGPR on the plant's roots, thereby restricting entry of a foliar pathogen through stomatal pores present in the leaves. Another method for promoting the health of a plant comprises administering acetoin to the plant or the soil in an amount effective to increase pathogen resistance in aerial parts of the plant.

Abstract: Methods for producing greater biomass in a plant, increasing the drought tolerance of a plant, producing a decreased lignin concentration in a plant, producing a greater iron concentration in a plant, or inhibiting fungal infection in a plant comprise administering Bacillus subtilis FB17 to the plant, the seed of the plant, or soil surrounding the plant or the seed in an amount effective to produce greater biomass, increase the drought tolerance, produce a decreased lignin concentration, produce a greater iron concentration, or inhibit fungal infection in the plant compared to an untreated plant, respectively. Agricultural carriers and seed coatings comprising Bacillus subtilis FB17 are provided. The biomass of a plant which has been administered Bacillus subtilis FB17 can be converted to a biofuel or can be used as a food crop or in other uses.

Abstract: Methods for producing greater biomass in a plant, increasing the drought tolerance of a plant, producing a decreased lignin concentration in a plant, producing a greater iron concentration in a plant, or inhibiting fungal infection in a plant comprise administering Bacillus subtilis FB17 to the plant, the seed of the plant, or soil surrounding the plant or the seed in an amount effective to produce greater biomass, increase the drought tolerance, produce a decreased lignin concentration, produce a greater iron concentration, or inhibit fungal infection in the plant compared to an untreated plant, respectively. Agricultural carriers and seed coatings comprising Bacillus subtilis FB17 are provided. The biomass of a plant which has been administered Bacillus subtilis FB17 can be converted to a biofuel or can be used as a food crop or in other uses.

Abstract: A method for promoting the health of a plant comprises administering malic acid to the plant or the soil in an amount effective to recruit plant growth promoting rhizobacteria (PGPR) to the plant. Administration of malic acid promotes biofilm formation of PGPR on the plant's roots, thereby restricting entry of a foliar pathogen through stomatal pores present in the leaves. Another method for promoting the health of a plant comprises administering acetoin to the plant or the soil in an amount effective to increase pathogen resistance in aerial parts of the plant.