Effects of enhancement of liquorice plants with dark septate endophytes on the root growth, glycyrrhizic acid and glycyrrhizin accumulation amended with organic residues

Abstract

Dark septate endophytes (DSE) is a diverse group of Ascomycetes fungi involved in a mutualistic symbiosis with plant roots, however, their ecological roles need further clarification. This study aimed to investigate how DSE (Acrocalymma vagum and Paraboeremia putaminum) affect liquorice (Glycyrrhiza uralensis) growth under additional sterilized fermented and unfermented organic residues. Two DSE strains could establish a positive symbiosis with the host plants depending on DSE species and residue availability. Specifically, A. vagum inoculation mainly promoted the development of lateral roots, whereas P. putaminum inoculation mainly improved the taproot development. Mantel test and structural equation model (SEM) analysis demonstrated that DSE associated with residues significantly positively influenced the plant biomass, taproot length, total root length, root diameter, glycyrrhizic acid and glycyrrhizin content. The greatest benefits of DSE inoculation occurred in fermented residue treatment. Variation in root growth can be attributed to the effects of DSE inoculation. As A. vagum exhibited positive effects on the plant biomass, root growth, and active ingredient content in liquorice plants under organic residues treatment, it was considered to be the best combination of A. vagum and fermented residues for the liquorice cultivation. These results contribute to the understanding of the ecological function of DSE fungi in nutrient deficiency lands.

Keywords

• Dark septate endophytes (DSE)
• Root development
• Active ingredient
• Organic residues
• Liquorice
• Symbiosis