A volatile producing Bacillus subtilis strain from the rhizosphere of Haloxylon ammodendron promotes plant root development

Abstract

AimsThe colonization of plant growth-promoting rhizobacteria (PGPR) along plant roots in turn facilitates their ability to promote plant growth and health. In this study, we found that Bacillus subtilis strain WM13-24 from the rhizosphere of Haloxylon ammodendron was able to promote the growth of both Arabidopsis and its host plant. Furthermore, we found that volatile organic compounds (VOCs) from strain WM13-24 could promote plant growth by stimulating lateral root formation and root hair growth. However, the molecular mechanism underlying WM13-24-stimulated root development is still unknown.MethodsIn this study, a series of Arabidopsis mutants defective in specific plant hormone signaling pathways were used as materials to preliminarily study the effect of VOCs released by strain WM13-24 on plant root development through genetic and pharmacological methods. The volatile compounds of strain WM13-24 were identified by solid-phase microextraction gas chromatography-mass spectrometry (SPME–GC–MS).ResultsWM13-24 was able to promote the growth of both Arabidopsis and its host plant, H. ammodendron. Auxin signaling and transport played a crucial role in WM13-24-stimulated changes of root architectures in Arabidopsis. SPME–GC–MS analysis revealed that WM13-24 produces various classes of compounds. We further showed that 2,3-butanediol and benzyl alcohol were active in promoting plant growth and the growth responses of plants to the two VOCs were concentration dependent.ConclusionsAll these results suggested that VOCs emitted from B. subtilis strain WM13-24 from the rhizosphere of H. ammodendron improves root development depending on auxin signaling.