Multilayered Regulation of Ethylene Induction Plays a Positive Role in Arabidopsis Resistance against Pseudomonas syringae.
Ethylene, a key phytohormone involved in plant-pathogen interaction, plays a positive role in plant resistance against fungal pathogens. However, its function in plant bacterial resistance remains unclear. Here, we report a detailed analysis of ethylene induction in Arabidopsis (Arabidopsis thaliana) in response to Pseudomonas syringae pv tomato DC3000 (Pst). Ethylene biosynthesis is highly induced in both pathogen/microbe-associated molecular pattern (PAMP)-triggered immunity and effector-triggered immunity (ETI), and the induction is potentiated by salicylic acid (SA) pretreatment. In addition, Pst actively suppresses PAMP-triggered ethylene induction in a type III secretion system-dependent manner. SA potentiation of ethylene induction is dependent mostly on MITOGEN-ACTIVATED PROTEIN KINASE6 (MPK6) and MPK3 and their downstream ACS2 and ACS6, two type I isoforms of 1-aminocyclopropane-1-carboxylic acid synthases (ACSs). ACS7, a type III ACS whose expression is enhanced by SA pretreatment, is also involved. Pst expressing the avrRpt2 effector gene (Pst-avrRpt2), which is capable of triggering ETI, induces a higher level of ethylene production, and the elevated portion is dependent on SALICYLIC ACID INDUCTION DEFICIENT2 and NONEXPRESSER OF PATHOGENESIS-RELATED GENE1, two key players in SA biosynthesis and signaling. High-order ACS mutants with reduced ethylene induction are more susceptible to both Pst and Pst-avrRpt2, demonstrating a positive role of ethylene in plant bacterial resistance mediated by both PAMP-triggered immunity and ETI.
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.).
Rongxia
http://orcid.org/0000-0002-6826-9239
R
Guan
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.).
Jianbin
J
Su
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.).
Xiangzong
X
Meng
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.).
Sen
http://orcid.org/0000-0002-5457-3483
S
Li
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.).
Yidong
Y
Liu
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.).
Juan
J
Xu
Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China (R.G.); Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211 (R.G., J.S., X.M., Y.L., S.Z.); and State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China (J.S., S.L., J.X.) zhangsh@missouri.edu.
Shuqun
http://orcid.org/0000-0003-2959-6461
S
Zhang
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D060467:Disease Resistance / Q000187:drug effects / Q000276:immunology*; D004789:Enzyme Activation / Q000187:drug effects; D005030:Ethylenes / Q000096:biosynthesis / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D057865:Plant Immunity / Q000187:drug effects; D020033:Protein Isoforms / Q000378:metabolism; D044224:Pseudomonas syringae / Q000187:drug effects / Q000502:physiology*; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D005030:Ethylenes; D000069452:Pathogen-Associated Molecular Pattern Molecules; D020033:Protein Isoforms; C036216:ethylene; D020928:Mitogen-Activated Protein Kinases; D020156:Salicylic Acid