Drought Sensitivity of Sugarcane Cultivars Shapes Rhizosphere Bacterial Community Patterns in Response to Water Stress.

Qi Liu,Weixing Duan,Yue Liu,Sasa Xie,Jicao Dao,Ziting Wang,Beilei Wei,Yunchang Peng,Xiaowen Zhao,Yuanjun Xing

doi:10.3389/fmicb.2021.732989

Abstract

Rhizosphere bacteria, the main functional microorganisms inhabiting the roots of terrestrial plants, play important roles in regulating plant growth and environmental stress resistance. However, limited information is available regarding changes occurring within the structure of the root microbial community and the response mechanisms of host plants that improve adaptability to drought stress. In this study, we conducted an experiment on two sugarcane varieties with different drought tolerance levels under drought and control treatments and analyzed the rhizosphere bacterial communities using 16S rRNA high-throughput sequencing. Correlation analysis results clarified the influence of various factors on the rhizosphere bacterial community structure. Drought stress reduced the diversity of the bacterial community in the rhizosphere of sugarcane. Interestingly, the bacterial community of the drought-sensitive sugarcane cultivar GT39 changed more than that of the drought-tolerant cultivar ZZ9. In addition, ZZ9 had a high abundance of drought-resistant bacteria in the rhizosphere under optimal soil water conditions, whereas GT39 accumulated a large number of drought-resistant bacteria only under drought stress. GT39 mainly relied on Actinobacteria in its response to drought stress, and the abundance of this phylum was positively correlated with soil acid phosphatase and protease levels. In contrast, ZZ9 mainly relied on Bacilli in its response to drought stress, and the abundance of this class was positively correlated with only soil acid phosphatase levels. In conclusion, drought stress can significantly reduce the bacterial diversity and increase the abundance of drought-resistant bacteria in the sugarcane rhizosphere. The high abundance of drought-resistant bacteria in the rhizosphere of drought-tolerant cultivars under non-drought conditions is an important factor contributing to the high drought adaptability of these cultivars. Moreover, the core drought-resistant bacteria of the sugarcane rhizosphere and root exudates jointly affect the resistance of sugarcane to drought.

Highlights

Plants grow in dynamic environments to which they exhibit remarkable adaptations (Butt et al, 2019; Kundariya et al, 2020)
The Soil organic carbon (SOC), total nitrogen (TN), and available phosphorus (AP) contents in the rhizosphere soil were higher under the control treatment than under drought treatment
Soil organic carbon and TN were significantly correlated with cultivar and water treatment, whereas AP was significantly correlated only with drought stress (Table 1)

Summary

Introduction

Plants grow in dynamic environments to which they exhibit remarkable adaptations (Butt et al, 2019; Kundariya et al, 2020). The mechanisms associated with plant responses to drought stress have been extensively studied in terms of morphology, physiology, and genetics, the effects of drought on soil microorganisms remain poorly understood (Zhao et al, 2016; Aimin et al, 2018; Li P. et al, 2019). Investigation of these effects could provide insights into the resistance of plants to environmental stress (Jurburg et al, 2017; Krause et al, 2018)

Methods

Results

Conclusion