Small Molecule Inhibitors Specifically Targeting the Type III Secretion System of Xanthomonas oryzae on Rice

• Published in: International journal of molecular sciences 2019-02, Vol.20 (4), p.971
• Main Authors: Tao, Hui, Fan, Su-Su, Jiang, Shan, Xiang, Xuwen, Yan, Xiaojing, Zhang, Lian-Hui, Cui, Zi-Ning
• Format: Article
• Language: English
• Subjects: Antibiotics; Bacteria; Gene expression; Gene Expression Regulation, Bacterial - drug effects; Genes; Genes, Plant; Gram-negative bacteria; Inhibitors; Microorganisms; Nicotiana - microbiology; Oryza - drug effects; Oryza - genetics; Oryza - microbiology; Pathogens; Plant Diseases - microbiology; Promoter Regions, Genetic; Proteins; Salmonella; Secretion; Signal transduction; small molecule inhibitors; Small Molecule Libraries - analysis; Small Molecule Libraries - chemistry; Small Molecule Libraries - pharmacology; T3SS; Tobacco; Type III Secretion Systems - metabolism; Virulence; Virulence factors; Xanthomonas - drug effects; Xanthomonas - growth & development; Xanthomonas - metabolism; Xanthomonas oryzae pv. oryzae (Xoo)
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms20040971

The initiative strategy for the development of novel anti-microbial agents usually uses the virulence factors of bacteria as a target, without affecting their growth and survival. The type III secretion system (T3SS), one of the essential virulence factors in most Gram-negative pathogenic bacteria because of its highly conserved construct, has been regarded as an effective target that developed new anti-microbial drugs. pv. ( ) causes leaf blight diseases and is one of the most important pathogens on rice. To find potential anti-virulence agents against this pathogen, a number of natural compounds were screened for their effects on the T3SS of . Three of 34 compounds significantly inhibited the promoter activity of the harpin gene, , and were further checked for their impact on bacterial growth and on the hypersensitive response (HR) caused by on non-host tobacco plants. The results indicated that treatment of with CZ-1, CZ-4 and CZ-9 resulted in an obviously attenuated HR without affecting bacterial growth and survival. Moreover, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that the expression of the T3SS was suppressed by treatment with the three inhibitors. The mRNA levels of representative genes in the hypersensitive response and pathogenicity ( ) cluster, as well as the regulatory genes and , were reduced. Finally, the in vivo test demonstrated that the compounds could reduce the disease symptoms of on the rice cultivar ( ) IR24.