Draft Genome Analysis Offers Insights Into the Mechanism by Which Streptomyces chartreusis WZS021 Increases Drought Tolerance in Sugarcane.

Zhen Wang,Manoj Kumar Solanki,Yang-Rui Li,Li-Tao Yang,Zhuo-Xin Yu,Qian-Li An,Deng-Feng Dong

doi:10.3389/fmicb.2018.03262

Abstract

Drought directly affects sugarcane production. Plant growth-promoting bacteria have gained attention as growth promoters of plants under abiotic stresses. The present study focused on genome assessment of the plant-beneficial endophyte Streptomyces chartreusis WZS021 and its vital role in sugarcane plants under drought stress. Based on in vitro plant growth-promoting trait analyses, WZS021 had multiple abilities, including tolerance to drought and production of 1-aminocyclopropane-1-carboxylic deaminase, siderophores, and indole acetic acid. We confirmed root colonization of sugarcane transplants by WZS021 by a sterile sand assay and scanning electron microscopy. Plants inoculated with strain WZS021 had a positive influence on the root parameters such as length and biomass when compared to the control plants. A comparative study of the responses of two sugarcane varieties (ROC22 and B8) to different levels of drought stress in the presence or absence of WZS021 was conducted by assessing the plant chemistry. The expression of antioxidants in sugarcane leaves varied with water stress level. WZS021 inoculation improved the contents of chlorophyll, proline, and phytohormones, revealing some potential for the mechanisms by which this strain improves drought tolerance in sugarcane plants. We identified several genes that might be involved in the plant growth- and drought tolerance-promoting effects of this strain.

Highlights

Sugarcane is an important sugar and energy crop that is utilized as a raw material in various industries
Streptomyces chartreusis strain WZS021 was screened for drought tolerance using polyethylene glycol (PEG) 6000
The growth of WZS021 was affected by water stress induced by PEG 6000; the cells were able to grow at a water potential of −0.30 MPa (Figure 1A)

Summary

Introduction

Sugarcane is an important sugar and energy crop that is utilized as a raw material in various industries. The sugar industry is the pillar of the economy in Guangxi Province. Guangxi is the largest sugar-producing province in China; it produces >60% of total sugar in the country (Li Y.R. et al, 2016). PGPR have been reported to improve drought tolerance in Arabidopsis (Timmusk and Wagner, 1999), pepper (Mayak et al, 2004b), tomato (Mayak et al, 2004b), wheat (Yandigeri et al, 2012), and pea (Belimov et al, 2009). The utilization of such bacteria might be an effective approach to stabilizing and increasing crop yield and improving water use efficiency in dryland farming (Marris, 2008; Glick, 2014; Gontiamishra et al, 2014)

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