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Front. Microbiol. | doi: 10.3389/fmicb.2018.02280

Melatonin Treatment Inhibits the Growth of Xanthomonas oryzae pv. oryzae

 Chen Xian1, sun cheng2,  Pedro Laborda1,  Ian Palmer3,  Zhengqing Fu3 and feng q. liu1*
  • 1Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences (JAAS), China
  • 2School of Medicine, Yangzhou Polytechnic Institute, China
  • 3Department of Biological Sciences,, University of South Carolina, United States

Xanthomonas oryzae pv. oryzae (Xoo) causes rice bacterial blight, one of the most widespread and destructive diseases in rice-growing regions worldwide. Melatonin enhances pathogen resistance by inducing the plant innate immunity, but the direct effect of melatonin on plant pathogenic bacteria is poorly understood. In this study, we investigated the direct effects of melatonin on Xoo. Exogenous melatonin at 200 μg/mL significantly inhibited the proliferation of Xoo and reduced the mRNA expression of 5 cell-division genes. Melatonin at 200 μg/mL also inhibited the motility and biofilm formation of Xoo. Notably, melatonin changed the cell structure of Xoo length. To provide deeper insight into the mechanisms underlying this antibacterial activity, we examined global gene expression changes in PXO99 in response to the application of 200 μg/mL melatonin using RNA sequencing (RNA-seq). A wide range of DEGs related to catalytic activity and metal-binding activity were down-regulated under melatonin treatment. The DEGs responsible for carbohydrate metabolism and amino acid metabolism were also down-regulated. These results suggest that the inhibitory mechanism of melatonin on Xoo proliferation may involve regulation of cell division, along with reducing the concentration or activity of enzymes involved in metabolism.

Keywords: Melatonin, Xanthomonas oryzae pv. oryzae, Transcriptome, antibacterial action, Growth

Received: 01 Jun 2018; Accepted: 06 Sep 2018.

Edited by:

Jack Wong, The Chinese University of Hong Kong, Hong Kong

Reviewed by:

Maximino Manzanera, Universidad de Granada, Spain
Shahper N. Khan, Interdisciplinary Nanotechnology Centre, Aligarh Muslim University, India  

Copyright: © 2018 Xian, cheng, Laborda, Palmer, Fu and liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. feng q. liu, Jiangsu Academy of Agricultural Sciences (JAAS), Institute of Plant Protection, Nanjing, China,