Allelopathy and the rhizospere bacterial community structure of Oxytropis ochrocephala.

Oxytropis ochrocephala,a toxic perennial legume grass,is widely distributed across the grasslands of western China.Developing effective control methods for O.ochrocephalarequires exploration of mechanisms contributing to its occurrence.Allelopathy is considered to be an underlying mechanism driving biological invasion in many plant species.In this study,the allelopathic effect of O.ochrocephalaon the growth of Medicago sativaand Lolium perenne was analyzed,and the soil bacterial community from the rhizosphere and non-rhizosphere soils of O.ochrocephala were compared to examine if the plants exert allelopathy by altering soil bacterial communities.We planted Medicago sativaand Lolium perenne with soil containing different concentrations of O.ochrocephalatissue powder.After growing for 60 d,plant height,biomass and chlorophyll content were measured.The results showed strong allelopathic effects on the growth of the two grass species with soil containing 5% O.ochrocephalatissue powder,in which plant height,biomass and chlorophyll content were significantly reduced.We compared the bacterial structure of O.ochrocephalarhizosphere and non-rhizosphere soils with 16 SrDNA sequencing.The data showed that the structure of the bacterial communities differed greatly and the percentage of some phyla,such as Proteobacteria,Actinobacteria and Acidobacteria,were significantly different.In addition,there were more OTUs(Operational Taxonomic Units)in the non-rhizosphere soil.Since bacteria from different phyla are considered to function discriminately,these changes mean it is highly likely that O.ochrocephalaimplements allelopathy by altering the structure of the rhizospere bacterial community,and accordingly promotes its growth and competes with other associated plants.These results will assist the development of controlling strategies for O.ochrocephalain the future.