AUTHOR=Jiang Shan , Li Hui , Ahmed Wasim , Xiang Xuwen , Song Gaopeng , Cui Zi-Ning 

TITLE=Discovery of Ethyl 2-Nitro-3-Arylacrylates Molecules as T3SS Inhibitor Reducing the Virulence of Plant Pathogenic Bacteria Xanthomonas

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01874

DOI=10.3389/fmicb.2019.01874

ISSN=1664-302X

ABSTRACT=<p><italic>Xanthomonas oryzae</italic> pv. <italic>oryzae</italic> (<italic>Xoo</italic>) is a gram-negative pathogen which causes leaf blight disease. Known traditional bactericides are not much more effective in inhibiting this bacteria than before. Selecting the virulence factor of the bacteria as the target without affecting their growth has been considered as a novel method for developing new anti-microbial drugs. Type III secretion systems (T3SS) are one of the important and highly conserved virulence factors in most gram-negative pathogens, which has been considered as an effective target to develop new anti-microbial drugs. In order to discover potential anti-microbial drugs against <italic>Xoo</italic> pathogens, a series of ethyl 2-nitro-3-arylacrylates compounds were screened. Among them, the compounds I-9, I-12, and I-13 could highly inhibit the promoter activity of a harpin gene <italic>hpa1</italic>, which were used to further check for the influence on bacterial growth and on the hypersensitive response (HR) caused by <italic>Xoo</italic> bacteria on non-host plants. The results showed that above compounds could reduce HR without affecting bacterial growth and survival. Moreover, qRT-PCR analysis indicated that treatment with the three inhibitors (I-9, I-12, and I-13) could suppress the expression of the <italic>Xoo</italic> T3SS in different extent. The mRNA levels of representative genes in the <italic>hrp</italic> cluster, including the key regulatory genes <italic>hrpG</italic> and <italic>hrpX</italic>, were decreased. Last but not least, <italic>in vivo</italic> test ensured that the above compounds reduced the disease symptoms of <italic>Xoo</italic> on the rice and <italic>Xcc</italic> on the Chinese radish.</p>