N-3-oxo-hexanoyl-homoserine lactone, a bacterial quorum sensing signal, enhances salt tolerance in Arabidopsis and wheat

Qian Zhao,Zhen-Hua Jia,Shui-Shan Song,Yao Li,Xiang-Yu Cao,Xiang-Yun Yang,Fang Liu

doi:10.1186/s40529-020-00283-5

Abstract

BackgroundN-acyl-homoserine lactones (AHLs) are the quorum sensing (QS) signal molecules to coordinate the collective behavior in a population in Gram-negative bacteria. Recent evidences demonstrate their roles in plant growth and defense responses.ResultsIn present study, we show that the treatment of plant roots with N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL), one molecule of AHLs family, resulted in enhanced salt tolerance in Arabidopsis and wheat. We found that the growth inhibition phenotype including root length, shoot length and fresh weight were significantly improved by 3OC6-HSL under salt stress condition. The physiological and biochemical analysis revealed that the contents of chlorophyll and proline were increased and the contents of MDA and Na+ and Na+/K+ ratios were decreased after 3OC6-HSL treatment in Arabidopsis and wheat under salt stress condition. Molecular analysis showed that 3OC6-HSL significantly upregulated the expression of salt-responsive genes including ABA-dependent osmotic stress responsive genes COR15a, RD22, ADH and P5CS1, ABA-independent gene ERD1, and ion-homeostasis regulation genes SOS1, SOS2 and SOS3 in Arabidopsis under salt stress condition.ConclusionsThese results indicated that 3OC6-HSL enhanced plant salt tolerance and ABA-dependent and ABA-independent signal pathways and SOS signaling might be involved in the induction of salt resistance by 3OC6-HSL in plants. Our data provide a new insight into the plant–microbe inter-communication.

Highlights

N-acyl-homoserine lactones (AHLs) are the quorum sensing (QS) signal molecules to coordinate the collective behavior in a population in Gram-negative bacteria
Proteomic analysis has revealed that the expression of over 150 proteins were significant changed after treated with two different AHL types, N-3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and N-3-oxo-hexadecanoyl-homoserine lactone (3OC16:1-HSL) in Medicago truncatula (Mathesius et al 2003), and the level of 53 proteins were accumulated induced by N-3-oxo-octanoyl-homoserine
Compared with the control plants, total chlorophyll content increased by 21.1% and 27.3% in 3OC6-HSL-treated Arabidopsis and wheat, respectively (Fig. 3a, d)

Summary

Introduction

N-acyl-homoserine lactones (AHLs) are the quorum sensing (QS) signal molecules to coordinate the collective behavior in a population in Gram-negative bacteria. In recent years, accumulating evidence indicates that AHLs have an impact on plant cells (Mathesius et al 2003; von Rad et al 2008; Liu et al 2012; Miao et al 2012; Schikora et al 2011; Shenk et al 2014; Zhao et al 2015, 2016). Plants change their gene expression, alter their protein profile, modify their development and enhance their defense responses if AHLs are present in their surroundings. Proteomic analysis has revealed that the expression of over 150 proteins were significant changed after treated with two different AHL types, N-3-oxo-dodecanoyl-homoserine lactone (3OC12-HSL) and N-3-oxo-hexadecanoyl-homoserine lactone (3OC16:1-HSL) in Medicago truncatula (Mathesius et al 2003), and the level of 53 proteins were accumulated induced by N-3-oxo-octanoyl-homoserine

Methods

Results

Conclusion