title: An abietane diterpenoid is a potent activator of systemic acquired resistance.
abstract: Abietane diterpenoids are major constituents of conifer resins that have important industrial and medicinal applications. However, their function in plants is poorly understood. Here we show that dehydroabietinal (DA), an abietane diterpenoid, is an activator of systemic acquired resistance (SAR), which is an inducible defense mechanism that is activated in the distal, non-colonized, organs of a plant that has experienced a local foliar infection. DA was purified as a SAR-activating factor from vascular sap of Arabidopsis thaliana leaves treated with a SAR-inducing microbe. Locally applied DA is translocated through the plant and systemically induces the accumulation of salicylic acid (SA), an important activator of defense, thus leading to enhanced resistance against subsequent infections. The NPR1 (NON-EXPRESSOR OF PR GENES1), FMO1 (FLAVIN-DEPENDENT MONOOXYGENASE1) and DIR1 (DEFECTIVE IN INDUCED RESISTANCE1) genes, which are critical for biologically induced SAR, are also required for the DA-induced SAR, which is further enhanced by azelaic acid, a defense priming molecule. In response to the biological induction of SAR, DA in vascular sap is redistributed into a SAR-inducing 'signaling DA' pool that is associated with a trypsin-sensitive high molecular weight fraction, a finding that suggests that DA-orchestrated SAR involves a vascular sap protein(s).
authors.affiliation: Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Chaturvedi
authors.forename: Barney
authors.initials: B
authors.lastname: Venables
authors.forename: Robby A
authors.initials: RA
authors.lastname: Petros
authors.forename: Vamsi
authors.initials: V
authors.lastname: Nalam
authors.forename: Maoyin
authors.initials: M
authors.lastname: Li
authors.forename: Xuemin
authors.initials: X
authors.lastname: Wang
authors.forename: Larry J
authors.initials: LJ
authors.lastname: Takemoto
authors.forename: Jyoti
authors.initials: J
authors.lastname: Shah
mesh_terms: D045784:Abietanes / Q000737:chemistry / Q000276:immunology*; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D060467:Disease Resistance; D050556:Fatty Acid-Binding Proteins; D018506:Gene Expression Regulation, Plant; D053147:Plant Exudates / Q000737:chemistry / Q000276:immunology; D015398:Signal Transduction
chemical_list: D045784:Abietanes; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; C105496:NPR1 protein, Arabidopsis; D053147:Plant Exudates; C576115:dehydroabietinal; C466483:dir1-1 protein, Arabidopsis