Glomus mosseae Inoculation Improves the Root System Architecture, Photosynthetic Efficiency and Flavonoids Accumulation of Liquorice under Nutrient Stress.

Meilan Chen,Ye Sheng,Hongyan Qiu,Zhi Chao,Pengying Li,Luqi Huang,Xiuteng Zhou,Guang Yang

doi:10.3389/fpls.2017.00931

Abstract

The poor quality and low productivity of cultivated liquorice (Glycyrrhiza uralensis) continues to put pressure on wild plant populations. As arbuscular mycorrhizal fungi are known to support plant growth and in some cases even to enhance the accumulation of valuable molecules in the plant, the effect of Glomus mosseae on the growth and active ingredient contents was evaluated in liquorice plants grown under nutrient deficiency. We created a nutrient-deficient environment by mixing paddy soil, washed river sand, and pumice at a ratio of 1:5:1. Our results showed that the inoculation of pot-grown liquorice plants with G. mosseae significantly increased the shoot and root biomass (by 25- and 17-folds, respectively) and the contents of glycyrrhizic acid, liquiritin, isoliquiritin, and isoliquiritigenin in the main root (by 1.6-, 4.8-, 6.5-, and 4.4-folds, respectively). Both isoliquiritin and isoliquiritigenin were detectable in the lateral roots of the plants inoculated with G. mosseae, but not in plants without G. mosseae inoculation. G. mosseae inoculation improved the features of the root system and increased photosynthetic efficiency of liquorice. The uptake of P and K by liquorice increased when G. mosseae was inoculated, leading to the depletion of these macronutrients in the soil; G. mosseae also improved the availability of Mg, Cu, Zn, and Mn. Based on these results, we concluded that the inoculation of liquorice plants with G. mosseae is beneficial, particularly for those grown in nutrient-deficient soil, and such positive effect is related to the improvement of the root system and an increased photosynthetic efficiency.

Highlights

Liquorice (Glycyrrhiza uralensis Fisch.) is a leguminous species grown widely in the northern, north-eastern, and north-western regions of China1
We examined the effect of the treatment on detailed morphological changes of the host plant roots, its utilization of mineral nutrients in soil, and photosynthetic efficiency of the aerial parts
Among the liquorice plants treated with GM, 85% ± 3% were successfully colonized by G. mosseae as shown by the presence of hyphae, arbuscules, and vesicles

Summary

Introduction

Liquorice (Glycyrrhiza uralensis Fisch.) is a leguminous species grown widely in the northern, north-eastern, and north-western regions of China. Liquorice cultivation is targeted at nutrient-poor soils. In order to obtain a satisfactory yield and quality, intensive fertilization is indispensable (Fu et al, 2013; Fan et al, 2016). Already known advantages of symbiosis with AMF include: the promotion of vegetative growth (Huang et al, 2010; Khabou et al, 2014), secondary metabolite content (Sarkar et al, 2015; Urcoviche et al, 2015), and nutrient acquisition of plant (Weisany et al, 2016); the improvement of soil conditions for the host plants by improving the soil structure and soil aggregate stability (Piotrowski et al, 2004; Van der Heijden et al, 2006); and the contribution to the ecosystem stability (Feddermann et al, 2010)

Methods

Results

Conclusion