Liu Fang, Zhao Qian, Jia Zhenhua, Zhang Siyuan, Wang Juan, Song Shuishan, Jia Yantao
State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2022 Jun 14;13:886268. doi: 10.3389/fpls.2022.886268. eCollection 2022.
Many Gram-negative bacteria use small signal molecules, such as -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, -3-oxo-octanoyl homoserine lactone (3OC8-HSL), enhanced Arabidopsis resistance to the hemi-biotrophic bacteria pv. DC3000 through priming the salicylic acid (SA) pathway. Here, we found that 3OC8-HSL could also prime resistance to the necrotrophic bacterium ssp. () through the jasmonic acid (JA) pathway, and is dependent on auxin responses, in both Chinese cabbage and Arabidopsis. The subsequent invasion triggered JA accumulation and increased the down-stream genes' expressions of JA synthesis genes (, , and ) and JA response genes ( and ). The primed state was not observed in the Arabidopsis - and mutants, which indicated that the primed resistance to 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 and 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 , 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.
许多革兰氏阴性菌利用小信号分子，如N-酰基高丝氨酸内酯（AHLs），来相互交流并协调它们的群体行为。最近，越来越多的证据表明，长链群体感应信号在引发植物防御反应中发挥作用。我们之前的研究表明，一种短链信号分子，N-3-氧代辛酰高丝氨酸内酯（3OC8-HSL），通过激活水杨酸（SA）途径增强了拟南芥对半活体营养型细菌丁香假单胞菌番茄致病变种（Pseudomonas syringae pv. tomato DC3000）的抗性。在此，我们发现3OC8-HSL还能通过茉莉酸（JA）途径引发对坏死营养型细菌胡萝卜软腐欧文氏菌（Erwinia carotovora ssp. carotovora）的抗性，且在大白菜和拟南芥中均依赖于生长素反应。随后的胡萝卜软腐欧文氏菌侵染引发了JA积累，并增加了JA合成基因（LOX2、AOS和AOC）和JA反应基因（PDF1.2和VSP2）的下游基因表达。在拟南芥jar1和coi1突变体中未观察到引发状态，这表明对胡萝卜软腐欧文氏菌的引发抗性依赖于JA途径。3OC8-HSL不会从根部传递到叶片，它会诱导幼苗中吲哚乙酸（IAA）积累以及IAA19和IAA29生长素响应基因的表达。当用外源IAA（10 μM）预处理拟南芥和大白菜根部时，植株激活了JA途径并增强了对胡萝卜软腐欧文氏菌的抗性，这意味着JA途径通过与生长素途径协同作用参与了AHL引发。我们的研究结果为大白菜软腐病的防治提供了新策略，并为将群体感应AHL信号分子用作新型激发子提供了理论支持。
