AUTHOR=Liu Fang , Zhao Qian , Jia Zhenhua , Zhang Siyuan , Wang Juan , Song Shuishan , Jia Yantao 

TITLE=N-3-Oxo-Octanoyl Homoserine Lactone Primes Plant Resistance Against Necrotrophic Pathogen Pectobacterium carotovorum by Coordinating Jasmonic Acid and Auxin-Signaling Pathways

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.886268

DOI=10.3389/fpls.2022.886268

ISSN=1664-462X

ABSTRACT=<p>Many Gram-negative bacteria use small signal molecules, such as <italic>N</italic>-acyl-homoserine lactones (AHLs), to communicate with each other and coordinate their collective behaviors. Recently, increasing evidence has demonstrated that long-chained quorum-sensing signals play roles in priming defense responses in plants. Our previous work indicated that a short-chained signal, <italic>N</italic>-3-oxo-octanoyl homoserine lactone (3OC8-HSL), enhanced Arabidopsis resistance to the hemi-biotrophic bacteria <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 through priming the salicylic acid (SA) pathway. Here, we found that 3OC8-HSL could also prime resistance to the necrotrophic bacterium <italic>Pectobacterium carotovorum</italic> ssp. <italic>carotovorum</italic> (<italic>Pcc</italic>) through the jasmonic acid (JA) pathway, and is dependent on auxin responses, in both Chinese cabbage and Arabidopsis. The subsequent <italic>Pcc</italic> invasion triggered JA accumulation and increased the down-stream genes’ expressions of JA synthesis genes (<italic>LOX</italic>, <italic>AOS</italic>, and <italic>AOC</italic>) and JA response genes (<italic>PDF1.2</italic> and <italic>VSP2</italic>). The primed state was not observed in the Arabidopsis <italic>coi1</italic>-<italic>1</italic> and <italic>jar1-1</italic> mutants, which indicated that the primed resistance to <italic>Pcc</italic> was dependent on the JA pathway. The 3OC8-HSL was not transmitted from roots to leaves and it induced indoleacetic acid (IAA) accumulation and the <italic>DR5</italic> and <italic>SAUR</italic> auxin-responsive genes’ expressions in seedlings. When Arabidopsis and Chinese cabbage roots were pretreated with exogenous IAA (10 μM), the plants had activated the JA pathway and enhanced resistance to <italic>Pcc</italic>, which implied that the JA pathway was involved in AHL priming by coordinating with the auxin pathway. Our findings provide a new strategy for the prevention and control of soft rot in Chinese cabbage and provide theoretical support for the use of the quorum-sensing AHL signal molecule as a new elicitor.</p>