title: Discrimination of Arabidopsis PAD4 activities in defense against green peach aphid and pathogens.
abstract: The Arabidopsis (Arabidopsis thaliana) lipase-like protein PHYTOALEXIN DEFICIENT4 (PAD4) is essential for defense against green peach aphid (GPA; Myzus persicae) and the pathogens Pseudomonas syringae and Hyaloperonospora arabidopsidis. In basal resistance to virulent strains of P. syringae and H. arabidopsidis, PAD4 functions together with its interacting partner ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) to promote salicylic acid (SA)-dependent and SA-independent defenses. By contrast, dissociated forms of PAD4 and EDS1 signal effector-triggered immunity to avirulent strains of these pathogens. PAD4-controlled defense against GPA requires neither EDS1 nor SA. Here, we show that resistance to GPA is unaltered in an eds1 salicylic acid induction deficient2 (sid2) double mutant, indicating that redundancy between EDS1 and SID2-dependent SA, previously reported for effector-triggered immunity conditioned by certain nucleotide-binding-leucine-rich repeat receptors, does not explain the dispensability of EDS1 and SID2 in defense against GPA. Mutation of a conserved serine (S118) in the predicted lipase catalytic triad of PAD4 abolished PAD4-conditioned antibiosis and deterrence against GPA feeding, but S118 was dispensable for deterring GPA settling and promoting senescence in GPA-infested plants as well as for pathogen resistance. These results highlight distinct molecular activities of PAD4 determining particular aspects of defense against aphids and pathogens.
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, Texas 76203, USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Louis
authors.forename: Enrico
authors.initials: E
authors.lastname: Gobbato
authors.forename: Hossain A
authors.initials: HA
authors.lastname: Mondal
authors.forename: Bart J
authors.initials: BJ
authors.lastname: Feys
authors.forename: Jane E
authors.initials: JE
authors.lastname: Parker
authors.forename: Jyoti
authors.initials: J
authors.lastname: Shah
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D000898:Antibiosis / Q000276:immunology; D001042:Aphids / Q000502:physiology*; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D060467:Disease Resistance / Q000276:immunology; D005247:Feeding Behavior; D018506:Gene Expression Regulation, Plant; D008954:Models, Biological; D008969:Molecular Sequence Data; D044742:Peronospora / Q000502:physiology*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology / Q000469:parasitology / Q000517:prevention & control; D053147:Plant Exudates / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development / Q000382:microbiology / Q000469:parasitology; D058526:Plant Vascular Bundle / Q000378:metabolism / Q000382:microbiology / Q000469:parasitology; D027861:Prunus / Q000469:parasitology*; D044224:Pseudomonas syringae / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D000596:Amino Acids; D029681:Arabidopsis Proteins; D053147:Plant Exudates; D012333:RNA, Messenger; D002265:Carboxylic Ester Hydrolases; C400766:PAD4 protein, Arabidopsis