Plant growth-promoting bacterium Pseudomonas fluorescens FR1 secrets a novel type of extracellular polyhydroxybutyrate polymerase involved in abiotic stress response in plants

Abstract

Objectives Identification of novel microbial factors contributing to plant protection against abiotic stress. Results The genome of plant growth-promoting bacterium Pseudomonas fluorescens FR1 contains a short mobile element encoding a novel type of extracellular polyhydroxybutyrate (PHB) polymerase (PhbC) associated with a type I secretion system. Genetic analysis using a phbC mutant strain and plants showed that this novel extracellular enzyme is related to the PHB production in planta and suggests that PHB could be a beneficial microbial compound synthesized during plant adaptation to cold stress. Conclusion Extracellular PhbC can be used as a new tool for improve crop production under abiotic stress.