Pseudomonas Species in Soil as a Natural Resource for Plant Growth Promotion and Biocontrol Characteristics - An Overview

Abstract

Plant growth-promoting Pseudomonads regulate plant growth by several direct and indirect mechanisms; direct mechanisms include producing phytohormones, increasing nutrient availability and indirect mechanisms include suppressing soil-borne plant pathogens by the production of siderophores, antibiotics, inducing systemic resistance and competing with pathogens. Pseudomonas spp. in soil has been reported from diverse ecological niches and has been well-documented as a model organism for regulating plant growth promotion. These bacteria are endowed with tremendous genetic and metabolic diversity and serve multiple ecological functions in the soil ecosystem. This versatile genus is one of the most commercially exploited bacteria in agriculture. The potential of the different species of Pseudomonas has not been realized sufficiently and requires emphasis on sustainable agriculture for the benefit of humankind. Research in the past decade has revealed that several species of Pseudomonas other than the common species such as P. fluorescens, P. putida, P. aeruginosa, have both plant growth promotion and biocontrol characteristics and have not been commercially exploited. According to the recent List of Prokaryotic names with Standing in Nomenclature (LPSN) there are 507 species of Pseudomonas and the present literature review brings out that 7.29% of them posses plant growth promotion (PGP) and biocontrol traits and thus can be utilized as biofertilizers in the field of agriculture. The role of different Pseudomonas spp. in the supply of plant nutrients and biocontrol of soilborne plant pathogens are covered in this review.