title: Mono- and digalactosyldiacylglycerol lipids function nonredundantly to regulate systemic acquired resistance in plants.
abstract: The plant galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) have been linked to the anti-inflammatory and cancer benefits of a green leafy vegetable diet in humans due to their ability to regulate the levels of free radicals like nitric oxide (NO). Here, we show that DGDG contributes to plant NO as well as salicylic acid biosynthesis and is required for the induction of systemic acquired resistance (SAR). In contrast, MGDG regulates the biosynthesis of the SAR signals azelaic acid (AzA) and glycerol-3-phosphate (G3P) that function downstream of NO. Interestingly, DGDG is also required for AzA-induced SAR, but MGDG is not. Notably, transgenic expression of a bacterial glucosyltransferase is unable to restore SAR in dgd1 plants even though it does rescue their morphological and fatty acid phenotypes. These results suggest that MGDG and DGDG are required at distinct steps and function exclusively in their individual roles during the induction of SAR.
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
authors.forename: Qing-Ming
authors.initials: QM
authors.lastname: Gao
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
authors.forename: Keshun
authors.initials: K
authors.lastname: Yu
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Xia
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Shine
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; Qingdao Agricultural University, Number 700, Changcheng Road, Chengyang District, Qingdao City 266109, PRC.
authors.forename: Caixia
authors.initials: C
authors.lastname: Wang
authors.affiliation: Agricultural Research Service, United States Department of Agriculture, Washington State University, Prosser, WA 99350, USA.
authors.forename: DuRoy
authors.initials: D
authors.lastname: Navarre
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA. Electronic address: apkach2@uky.edu.
authors.forename: Aardra
authors.initials: A
authors.lastname: Kachroo
authors.affiliation: Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA. Electronic address: pk62@uky.edu.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kachroo
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics; D003517:Cyclopentanes / Q000378:metabolism; D060467:Disease Resistance; D038983:Galactolipids / Q000502:physiology*; D005700:Galactosyltransferases / Q000235:genetics; D050356:Lipid Metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D054883:Oxylipins / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology; D020156:Salicylic Acid / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D038983:Galactolipids; D054883:Oxylipins; C007388:digalactosyldiacylglycerol; C009909:monogalactosyldiacylglycerol; D009569:Nitric Oxide; C011006:jasmonic acid; C119967:DGD1 protein, Arabidopsis; D005700:Galactosyltransferases; D020156:Salicylic Acid