IAA production and other plant growth promoting traits of endophytic bacteria from apple tree

Abstract

All plants in nature harbor a diverse community of endophytic bacteria. They can produce a wide range of various compounds, which can positively affect the host plant growth. Endophytes can participate in providing plant with nutrients, competing with plants pathogens or directly effecting the plant growth by synthesis of phytohormones. In this study, endophytic bacteria associated with apple tree buds were isolated, characterized and tested for their ability to produce the plant hormone IAA (indole 3 acetic acid). Nine isolates were shown to produce IAA. Amounts of IAA produced in culture varied between 0.12–0.24 micrograms per milligram of protein. Several bacterial endophytes were shown to produce siderophores and substances which inhibited the growth of the test strain. We also screened the isolates for other PGP traits, as abilities to solubilize phosphate and fix nitrogen. Our results suggest that IAA production and other PGB traits are common among apple tree endophytic bacteria. Keywords: Bacterial endophytes, plant growth promoting bacteria, indole-3 acetic acid production, Malus domestica