title: The ammonium/nitrate ratio is an input signal in the temperature-modulated, SNC1-mediated and EDS1-dependent autoimmunity of nudt6-2 nudt7.
abstract: AtNUDT7 was reported to be a negative regulator of EDS1-mediated immunity in Arabidopsis. However, the underlying molecular and genetic mechanism of the AtNUDT7-regulated defense pathway remains elusive. Here we report that AtNUDT7 and its closest paralog AtNUDT6 function as novel negative regulators of SNC1, a TIR-NB-LRR-type R gene. SNC1 is upregulated at transcriptional and possibly post-transcriptional levels in nudt6-2 nudt7. The nudt6-2 nudt7 double mutant exhibits autoimmune phenotypes that are modulated by temperature and fully dependent on EDS1. The nudt6-2 nudt7 mutation causes EDS1 nuclear accumulation shortly after the establishment of autoimmunity caused by the temperature shift. We found that a low ammonium/nitrate ratio in growth media leads to a higher level of nitrite-dependent nitric oxide (NO) production in nudt6-2 nudt7, and NO acts in a positive feedback loop with EDS1 to promote the autoimmunity. The low ammonium/nitrate ratio also enhances autoimmunity in snc1-1 and cpr1, two other autoimmune mutants in Arabidopsis. Our study indicates that Arabidopsis senses the ammonium/nitrate ratio as an input signal to determine the amplitude of the EDS1-mediated defense response, probably through the modulation of NO production.
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.|State Key Laboratory of Genetic Engineering, Institute of Plant Biology, Department of Biochemistry and Molecular Biology, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.|Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wen
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Plant Biology, Department of Biochemistry and Molecular Biology, School of Life Sciences, Fudan University, Shanghai, China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Ge
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Yiji
authors.initials: Y
authors.lastname: Xia
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D064751:Ammonium Compounds / Q000378:metabolism / Q000494:pharmacology*; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D009243:NAD / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism / Q000494:pharmacology*; D009569:Nitric Oxide; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013696:Temperature; D000096964:Nudix Hydrolases
chemical_list: D000246:Adenosine Diphosphate Ribose; D064751:Ammonium Compounds; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D009243:NAD; D009566:Nitrates; D009569:Nitric Oxide; D011755:Pyrophosphatases; D000096964:Nudix Hydrolases; C118837:EDS1 protein, Arabidopsis; C482739:SNC1 protein, Arabidopsis; C000604989:NUDT6 protein, Arabidopsis