ntrC Contributes to Nitrogen Utilization, Stress Tolerance, and Virulence in Acidovorax citrulli
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Published:2023-03-16
Issue:3
Volume:11
Page:767
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ISSN:2076-2607
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Container-title:Microorganisms
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language:en
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Short-container-title:Microorganisms
Author:
Liu Dehua12, Zhao Mei34, Qiao Pei2, Li Zhanhong2, Chen Gong4, Guan Wei2, Bai Qingrong1, Walcott Ron4, Yang Yuwen25ORCID, Zhao Tingchang25
Affiliation:
1. College of Plant Protection, Jilin Agricultural University, Changchun 130118, China 2. State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China 3. Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing 100193, China 4. Department of Plant Pathology, University of Georgia, Athens, GA 30602, USA 5. National Nanfan Research Institute (Sanya), Chinese Academy of Agricultural Sciences, Sanya 572024, China
Abstract
Bacterial fruit blotch (BFB), caused by Acidovorax citrulli, severely damages watermelon, melon, and other cucurbit crops worldwide. Nitrogen, one of the most important limiting elements in the environment, is necessary for the growth and reproduction of bacteria. As a nitrogen-regulating gene, ntrC plays an important role in maintaining bacterial nitrogen utilization and biological nitrogen fixation. However, the role of ntrC has not been determined for A. citrulli. In this study, we constructed a ntrC deletion mutant and a corresponding complementary strain in the background of the A. citrulli wild-type strain, Aac5. Through phenotype assays and qRT-PCR analysis, we investigated the role of ntrC in A. citrulli in nitrogen utilization, stress tolerance, and virulence against watermelon seedlings. Our results showed that the A. citrulli Aac5 ntrC deletion mutant lost the ability to utilize nitrate. The ntrC mutant strain also exhibited significantly decreased virulence, in vitro growth, in vivo colonization ability, swimming motility, and twitching motility. In contrast, it displayed significantly enhanced biofilm formation and tolerance to stress induced by oxygen, high salt, and copper ions. The qRT-PCR results showed that the nitrate utilization gene nasS; the Type III secretion system-related genes hrpE, hrpX, and hrcJ; and the pili-related gene pilA were significantly downregulated in the ntrC deletion mutant. The nitrate utilization gene nasT, and the flagellum-related genes flhD, flhC, fliA, and fliC were significantly upregulated in the ntrC deletion mutant. The expression levels of ntrC gene in the MMX-q and XVM2 media were significantly higher than in the KB medium. These results suggest that the ntrC gene plays a pivotal role in the nitrogen utilization, stress tolerance, and virulence of A. citrulli.
Funder
Hainan Province Science and Technology Special Fund China Earmarked Fund for Modern Agroindustry Technology Research System Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences Xinjiang Production and Construction Corps’ Scientific and Technological Research Plan Project in Agriculture National Key Research and Development Program of China
Subject
Virology,Microbiology (medical),Microbiology
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