title: LTP3 contributes to disease susceptibility in Arabidopsis by enhancing abscisic acid (ABA) biosynthesis.
abstract: Several plant lipid transfer proteins (LTPs) act positively in plant disease resistance. Here, we show that LTP3 (At5g59320), a pathogen and abscisic acid (ABA)-induced gene, negatively regulates plant immunity in Arabidopsis. The overexpression of LTP3 (LTP3-OX) led to an enhanced susceptibility to virulent bacteria and compromised resistance to avirulent bacteria. On infection of LTP3-OX plants with Pseudomonas syringae pv. tomato, genes involved in ABA biosynthesis, NCED3 and AAO3, were highly induced, whereas salicylic acid (SA)-related genes, ICS1 and PR1, were down-regulated. Accordingly, in LTP3-OX plants, we observed increased ABA levels and decreased SA levels relative to the wild-type. We also showed that the LTP3 overexpression-mediated enhanced susceptibility was partially dependent on AAO3. Interestingly, loss of function of LTP3 (ltp3-1) did not affect ABA pathways, but resulted in PR1 gene induction and elevated SA levels, suggesting that LTP3 can negatively regulate SA in an ABA-independent manner. However, a double mutant consisting of ltp3-1 and silent LTP4 (ltp3/ltp4) showed reduced susceptibility to Pseudomonas and down-regulation of ABA biosynthesis genes, suggesting that LTP3 acts in a redundant manner with its closest homologue LTP4 by modulating the ABA pathway. Taken together, our data show that LTP3 is a novel negative regulator of plant immunity which acts through the manipulation of the ABA-SA balance.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.|Institute of Forensic Science, Ministry of Public Security P.R.C., Beijing, 100038, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.|Hebei Academy of Forestry Science, Shijiazhuang, 050061, China.
authors.forename: Wenya
authors.initials: W
authors.lastname: Guo
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Feng
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.|Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Xiaorui
authors.initials: X
authors.lastname: Song
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Hou
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Saijun
authors.initials: S
authors.lastname: Tang
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Biological Sciences, China Agricultural University, Beijing, 100094, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis*; D042931:Aldehyde Oxidase / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060467:Disease Resistance; D004198:Disease Susceptibility; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018525:Germination / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010935:Plant Diseases / Q000382:microbiology; D044224:Pseudomonas syringae / Q000472:pathogenicity; D012639:Seeds / Q000235:genetics; D015398:Signal Transduction; D014774:Virulence
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid; C470342:AAO3 protein, Arabidopsis; D042931:Aldehyde Oxidase
keywords: AAO3; ABA biosynthesis; Arabidopsis; disease development; lipid transfer protein 3 (LTP3)