AUTHOR=Zhao Qian , Liu Fang , Song Cong , Zhai Tingting , He Ziwei , Ma Limei , Zhao Xuemeng , Jia Zhenhua , Song Shuishan 

TITLE=Diffusible signal factor primes plant immunity against Xanthomonas campestris pv. campestris (Xcc) via JA signaling in Arabidopsis and Brassica oleracea

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=13

YEAR=2023

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1203582

DOI=10.3389/fcimb.2023.1203582

ISSN=2235-2988

ABSTRACT=<sec><title>Background</title><p>Many Gram-negative bacteria use quorum sensing (QS) signal molecules to monitor their local population density and to coordinate their collective behaviors. The diffusible signal factor (DSF) family represents an intriguing type of QS signal to mediate intraspecies and interspecies communication. Recently, accumulating evidence demonstrates the role of DSF in mediating inter-kingdom communication between DSF-producing bacteria and plants. However, the regulatory mechanism of DSF during the <italic>Xanthomonas</italic>-plant interactions remain unclear.</p></sec><sec><title>Methods</title><p>Plants were pretreated with different concentration of DSF and subsequent inoculated with pathogen <italic>Xanthomonas campestris pv. campestris (Xcc)</italic>. Pathogenicity, phynotypic analysis, transcriptome combined with metabolome analysis, genetic analysis and gene expression analysis were used to evaluate the priming effects of DSF on plant disease resistance.</p></sec><sec><title>Results</title><p>We found that the low concentration of DSF could prime plant immunity against <italic>Xcc</italic> in both <italic>Brassica oleracea</italic> and <italic>Arabidopsis thaliana</italic>. Pretreatment with DSF and subsequent pathogen invasion triggered an augmented burst of ROS by DCFH-DA and DAB staining. CAT application could attenuate the level of ROS induced by DSF. The expression of <italic>RBOHD</italic> and <italic>RBOHF</italic> were up-regulated and the activities of antioxidases POD increased after DSF treatment followed by Xcc inoculation. Transcriptome combined with metabolome analysis showed that plant hormone jasmonic acid (JA) signaling involved in DSF-primed resistance to <italic>Xcc</italic> in Arabidopsis. The expression of JA synthesis genes (<italic>AOC2, AOS, LOX2, OPR3</italic> and <italic>JAR1</italic>), transportor gene (<italic>JAT1</italic>), regulator genes (<italic>JAZ1</italic> and <italic>MYC2</italic>) and responsive genes (<italic>VSP2, PDF1.2</italic> and <italic>Thi2.1</italic>) were up-regulated significantly by DSF upon Xcc challenge. The primed effects were not observed in JA relevant mutant <italic>coi1-1</italic> and <italic>jar1-1</italic>.</p></sec><sec><title>Conclusion</title><p>These results indicated that DSF-primed resistance against <italic>Xcc</italic> was dependent on the JA pathway. Our findings advanced the understanding of QS signal-mediated communication and provide a new strategy for the control of black rot in <italic>Brassica oleracea</italic>.</p></sec>