title: Arabidopsis thaliana FLOWERING LOCUS D is required for systemic acquired resistance.
abstract: Localized infection in plants often induces systemic acquired resistance (SAR), which provides long-term protection against subsequent infections. A signal originating in the SAR-inducing organ is transported to the distal organs, where it stimulates salicylic acid (SA) accumulation and priming, a mechanism that results in more robust activation of defenses in response to subsequent pathogen infection. In recent years, several metabolites that promote long-distance SAR signaling have been identified. However, the mechanism or mechanisms by which plants perceive and respond to the SAR signals are largely obscure. Here, we show that, in Arabidopsis thaliana, the FLOWERING LOCUS D (FLD) is required for responding to the SAR signals leading to the systemic accumulation of SA and enhancement of disease resistance. Although the fld mutant was competent in accumulating the SAR-inducing signal, it was unable to respond to the SAR signal that accumulates in petiole exudates of wild-type leaves inoculated with a SAR-inducing pathogen. Supporting FLD's role in systemic SAR signaling, we observed that dehydroabietinal and azelaic acid, two metabolites that, in wild-type plants, promote SAR-associated systemic accumulation of SA and priming, respectively, were unable to promote SAR in the fld mutant. FLD also participates in flowering, where it functions to repress expression of the flowering repressor FLOWERING LOCUS C (FLC). However, epistasis analysis indicates that FLD's function in SAR is independent of FLC.
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Vijayata
authors.initials: V
authors.lastname: Singh
authors.forename: Shweta
authors.initials: S
authors.lastname: Roy
authors.forename: Mrunmay Kumar
authors.initials: MK
authors.lastname: Giri
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Chaturvedi
authors.forename: Zulkarnain
authors.initials: Z
authors.lastname: Chowdhury
authors.forename: Jyoti
authors.initials: J
authors.lastname: Shah
authors.forename: Ashis Kumar
authors.initials: AK
authors.lastname: Nandi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060467:Disease Resistance; D018506:Gene Expression Regulation, Plant; D006655:Histone Deacetylases / Q000235:genetics* / Q000378:metabolism; D026161:MADS Domain Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010935:Plant Diseases / Q000276:immunology; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D030821:Plants, Genetically Modified; D044224:Pseudomonas syringae / Q000502:physiology*; D018749:RNA, Plant / Q000235:genetics; D020156:Salicylic Acid / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D026161:MADS Domain Proteins; D018749:RNA, Plant; C479923:flowering locus D protein, Arabidopsis; D006655:Histone Deacetylases; D020156:Salicylic Acid