Assaying the potential autotoxins and microbial community associated with Rehmannia glutinosa replant problems based on its ‘autotoxic circle’

Abstract

This study attempted to elucidate the underlying correlations among replant problems of Rehmannia glutinosa, the autotoxins and microbes within its root-zone soil. Different root-zone soils of R. glutinosa were collected to identify the potential autotoxins, to quantify the phenolic acids’ concentration and to analyse the microbial community composition. Bioassay was conducted to assess the autotoxic potential of these samples and candidate autotoxins. R. glutinosa autotoxicity was presented within a 20 cm radius of the plant. Concentrations of the phenolic acids were significantly higher within this range. Twenty compounds and 17 microbes emerged in this range after the R. glutinosa cultivation. Further seedling test showed that four selected compounds possessed conspicuous autotoxic activity and a synergistic effect was observed. Moreover, one potential beneficial fungi (99 % similar with Arthrobotrys oligospora) and one potential pathogens (100 % similar with Acremonium sclerotigenum) were identified. Our work defined the ‘autotoxic circle’ of R. glutinosa and identified the corresponding autotoxins and microbes. We suggest that R. glutinosa has various autotoxins and that these autotoxins and specific microbes deserve further investigation to unravel their interaction with R. glutinosa in replant problems’ occurrence.