Endophytic bacteria improve plant growth through induction of phytohormones related gene expression in jute

Abstract

Abstract Plants live in association with complex populations of microorganisms, including Plant Growth-Promoting Rhizobacteria (PGPR) which confers improved growth and enhanced stress tolerance to plants. This large and diverse group includes endophytic bacteria that can colonize the internal tissues of plants. This study aimed to identify the molecular and physiological characteristics of a non-rhizobial bacterial species from the surface-sterilized root of healthy and nematode-infested jute (Corchorus capsularis; Corchorus olitorius and an advanced variety of Corchorus olitorius, Robi-1), an annual fiber bearing plant species. Using universal primers to amplify bacterial 16S rDNA, we identified 59 culturable gram-positive bacterial isolates from healthy and nematode-infected jute plants. All the selected isolates were gram-positive of Bacillus and Staphylococcus genus. The endophytes were positive for pectinase, xylanase, cellulase, and phosphatase, all of which may influence jute physiology. Selected bacterial species increased the root length, shoot length, and germination rate. B. cereus significantly increased the growth phenotype and biomass of C. capsularis (CVL-1) whereas S. hominis showed significant growth increment in C. olitorius (O-9897) and the combination of all bacteria produced the same effect in the advanced line of C. olitorius (Robi-1). Higher expression of growth-promoting hormones GA-20 and GA-03 oxidase consolidate that plant growth was increased through induction of increased production of growth hormone gibberellin. Altogether, our results demonstrate that B. cereus (MCN3) and S. hominis (MON1) display plant growth-promoting traits of potential interest for agricultural applications.