Plant growth-promoting endophytic bacteria associated with Halocnemum strobilaceum (Pall.) M.Bieb and their plant beneficial traits

Abstract

Halocnemum strobilaceum (Pall.) M.Bieb. is a halophyte desert plant. The plant is known for its antioxidant, antimicrobial, insecticidal and phytoremediation properties. Halocnemum strobilaceum grows in severe salinity and drought conditions and its’ survival can be associated with activity of endophytic bacteria. The aim of the research was to reveal and study plant growth-promoting endophytic bacteria isolated from Halocnemum strobilaceum (Pall.) M.Bieb. The plants were collected from Kyzylkum desert in Uzbekistan. The endophytic bacteria were isolated from Halocnemum strobilaceum (Pall.) M.Bieb. tissues and screened for cotton (Gossypium hirsutum L.) growth-promoting activity. As a result the most active isolates HAST-2, HAST-7, HAST-9, HAST-10 and HAST-17 were selected. The cotton seeds’ inoculation with these bacterial isolates resulted in significant improvement of seeds germination, root and shoot length, and fresh plant weight due to their ability to fix nitrogen, produce indole-3-acetic acid (IAA), 1-aminocyclopropane-1-carboxylate (ACC) deaminase, siderophores and solubilize phosphates. The chosen isolates were identified using 16S rRNA gene analysis and registered in GenBank (NCBI) as Bacillus megaterium HAST-2, Bacillus aryabhattai HAST-7, Pseudomonas plecoglossicida HAST-9, Pseudomonas putida HAST-10 and Pseudomonas chlororaphis HAST-17. These strains can be used as bio-inoculants to improve the growth of cotton and other crops.