Effect ofBacillus velezensis JC-K3 on Endophytic Bacterial and Fungal Diversity in Wheat Under Salt Stress.

Chao Ji,Pengcheng Zhang,Jintai Li,Xiaohui Wang,Xin Song,Hui Cao,Qisheng Zhou,Huying Li,Zhizhang Chen,Chaohui Li,Qixiong Gao

doi:10.3389/fmicb.2021.802054

Abstract

Plant growth-promoting bacteria (PGPB) can effectively reduce salt damage in plants. Currently, there are many studies on the effects of PGPB on the microbial community structure of rhizosphere soil under salt stress, but fewer studies on the community structure of endophytic bacteria and fungi. We propose that inoculation of endophytic bacteria into the rhizosphere of plants can significantly affect the microbial community structure of the plant’s above-ground and underground parts, which may be the cause of the plant’s “Induced Systemic Tolerance.” The isolated endophytes were re-inoculated into the rhizosphere under salinity stress. We found that, compared with the control group, inoculation with endophytic Bacillus velezensis JC-K3 not only increased the accumulation of wheat biomass, but also increased the content of soluble sugar and chlorophyll in wheat, and reduced the absorption of Na in wheat shoots and leaves. The abundance of bacterial communities in shoots and leaves increased and the abundance of fungal communities decreased after inoculation with JC-K3. The fungal community richness of wheat rhizosphere soil was significantly increased. The diversity of bacterial communities in shoots and leaves increased, and the richness of fungal communities decreased. JC-K3 strain improved wheat’s biomass accumulation ability, osmotic adjustment ability, and ion selective absorption ability. In addition, JC-K3 significantly altered the diversity and abundance of endophytic and rhizosphere microorganisms in wheat. PGPB can effectively reduce plant salt damage. At present, there are many studies on the effect of PGPB on the microbial community structure in rhizosphere soil under salt stress, but there are few studies on the community structure changes of endophytic bacteria and fungi in plants.

Highlights

IntroductionAt least 20% of the cultivated land in the world is threatened by salinization to varying degrees (Zhu et al, 2011)
Soil salinity is one of the main manifestations of global land degradation
The results showed that the richness and diversity of bacterial and fungal communities in wheat roots decreased after inoculation with JC-K3 strain, but the difference was not significant (Table 2)

Summary

Introduction

At least 20% of the cultivated land in the world is threatened by salinization to varying degrees (Zhu et al, 2011). Plants can produce a certain amount of yield in saline soil habitats, most crops and trees have low salt tolerance. The yield is reduced by 70% in wheat, corn, rice, barley, and other major food crops under salt stress (Acquaah, 2007). The duration and severity of stress may cause varying degrees of damage to the plant. Initial osmotic stress, oxidative stress, and ionic toxicity may cause damage to plant cell membrane structures, nutritional imbalance, reduced antioxidant enzyme activity, and reduced photosynthesis (Rozema and Flowers, 2008; James et al, 2011). Plants have difficulty in absorbing K+, leading to nutrient deficiency, reduced productivity, and even death (James et al, 2011)

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