title: Sphingolipids in the root play an important role in regulating the leaf ionome in Arabidopsis thaliana.
abstract: Sphingolipid synthesis is initiated by condensation of Ser with palmitoyl-CoA producing 3-ketodihydrosphinganine (3-KDS), which is reduced by a 3-KDS reductase to dihydrosphinganine. Ser palmitoyltransferase is essential for plant viability. Arabidopsis thaliana contains two genes (At3g06060/TSC10A and At5g19200/TSC10B) encoding proteins with significant similarity to the yeast 3-KDS reductase, Tsc10p. Heterologous expression in yeast of either Arabidopsis gene restored 3-KDS reductase activity to the yeast tsc10Δ mutant, confirming both as bona fide 3-KDS reductase genes. Consistent with sphingolipids having essential functions in plants, double mutant progeny lacking both genes were not recovered from crosses of single tsc10A and tsc10B mutants. Although the 3-KDS reductase genes are functionally redundant and ubiquitously expressed in Arabidopsis, 3-KDS reductase activity was reduced to 10% of wild-type levels in the loss-of-function tsc10a mutant, leading to an altered sphingolipid profile. This perturbation of sphingolipid biosynthesis in the Arabidopsis tsc10a mutant leads an altered leaf ionome, including increases in Na, K, and Rb and decreases in Mg, Ca, Fe, and Mo. Reciprocal grafting revealed that these changes in the leaf ionome are driven by the root and are associated with increases in root suberin and alterations in Fe homeostasis.
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47906, USA.
authors.forename: Dai-Yin
authors.initials: DY
authors.lastname: Chao
authors.forename: Kenneth
authors.initials: K
authors.lastname: Gable
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Ivan
authors.initials: I
authors.lastname: Baxter
authors.forename: Charles R
authors.initials: CR
authors.lastname: Dietrich
authors.forename: Edgar B
authors.initials: EB
authors.lastname: Cahoon
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Guerinot
authors.forename: Brett
authors.initials: B
authors.lastname: Lahner
authors.forename: Shiyou
authors.initials: S
authors.lastname: Lü
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Markham
authors.forename: Joe
authors.initials: J
authors.lastname: Morrissey
authors.forename: Gongshe
authors.initials: G
authors.lastname: Han
authors.forename: Sita D
authors.initials: SD
authors.lastname: Gupta
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Harmon
authors.forename: Jan G
authors.initials: JG
authors.lastname: Jaworski
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Dunn
authors.forename: David E
authors.initials: DE
authors.lastname: Salt
mesh_terms: D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000483:Alleles; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival; D002874:Chromosome Mapping; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D007501:Iron / Q000378:metabolism; D008055:Lipids / Q000096:biosynthesis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010088:Oxidoreductases / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry*; D018517:Plant Roots / Q000378:metabolism*; D011110:Polymorphism, Genetic; D011188:Potassium / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012964:Sodium / Q000378:metabolism; D013107:Sphingolipids / Q000096:biosynthesis*; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008055:Lipids; D008565:Membrane Proteins; D013107:Sphingolipids; C065875:suberin; D012964:Sodium; D007501:Iron; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; C073900:3-ketosphinganine reductase; D011188:Potassium