Methods for promoting plant growth, methods for producing plant growth promoting substances, and proteins used therefor

An object of the present invention is to effectively use a microorganism having a function of promoting the growth of plants, particularly duckweed plants. [MEANS FOR SOLVING PROBLEMS] The present invention includes a step of allowing a microorganism (except Acinetobacter calcoaceticus P23) having at least one gene encoding the protein shown in SEQ ID NOs: 1 to 5 to coexist with a plant. A method for promoting plant growth is provided. According to the present invention, new microorganisms other than the P23 strain having a PGPC-related gene can be used, and the efficiency of biomass production can be increased by promoting the growth of plants, particularly duckweed plants. [Selection] Figure 5