title: Effects of eIFiso4G1 mutation on seed oil biosynthesis.
abstract: Fatty acid biosynthesis is a primary metabolic pathway that occurs in plastids, whereas the formation of glycerolipid molecules for the majority of cellular membrane systems and the deposition of storage lipid in seeds takes place in the cytosolic compartment. In this report, we present a study of an Arabidopsis mutant, ar21, with a novel seed fatty acid phenotype showing higher contents of eicosanoic acid (20:1) and oleic acid (18:1) and a reduced level of α-linolenic acid (18:3). A combination of map-based cloning and whole-genome sequencing identified the genetic basis underlying the fatty acid phenotype as a lesion in the plant-specific eukaryotic translation initiation factor eIFiso4G1. Transcriptome analysis on developing seeds revealed a reduced level of plastid-encoded genes. Specifically, decreases in both transcript and protein levels of an enzyme involved in fatty acid biosynthesis, the β-subunit of the plastidic heteromeric acetyl-CoA carboxylase (htACCase) encoded by accD, were evident in the mutant. Biochemical assays showed that the developing seeds of the mutant possessed a decreased htACCase activity in the plastid but an elevated activity of homomeric acetyl-CoA carboxylase (hmACCase). These results suggested that the increased 20:1 was attributable at least in part to the enhanced cytosolic hmACCase activity. We also detected a significant repression of FATTY ACID DESATURASE 3 (FAD3) during seed development, which correlated with a decreased 18:3 level in seed oil. Together, our study on a mutant of eIFiso4G1 uncovered multifaceted interactions between the cytosolic and plastidic compartments in seed lipid biosynthesis that impact major seed oil traits.
authors.affiliation: National Research Council Canada, 110 Gymnasium Place, Saskatoon, Saskatchewan, S7N 0W9, Canada.|Department of Plant Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan, S7N 5A8, Canada.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: National Research Council Canada, 110 Gymnasium Place, Saskatoon, Saskatchewan, S7N 0W9, Canada.
authors.forename: Wenyun
authors.initials: W
authors.lastname: Shen
authors.affiliation: National Research Council Canada, 110 Gymnasium Place, Saskatoon, Saskatchewan, S7N 0W9, Canada.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: National Research Council Canada, 110 Gymnasium Place, Saskatoon, Saskatchewan, S7N 0W9, Canada.
authors.forename: Yifang
authors.initials: Y
authors.lastname: Tan
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, No. 1, Shizi Shan Street, Wuhan, Hubei, 430070, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Gao
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, No. 1, Shizi Shan Street, Wuhan, Hubei, 430070, China.
authors.forename: Jinxiong
authors.initials: J
authors.lastname: Shen
authors.affiliation: Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada.
authors.forename: Yangdou
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Department of Botany, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Ljerka
authors.initials: L
authors.lastname: Kunst
authors.affiliation: National Research Council Canada, 110 Gymnasium Place, Saskatoon, Saskatchewan, S7N 0W9, Canada.
authors.forename: Jitao
authors.initials: J
authors.lastname: Zou
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D009154:Mutation; D010938:Plant Oils / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D039603:Eukaryotic Initiation Factor-4G; D005227:Fatty Acids; D010938:Plant Oils; C000607943:eIFiso4G1 protein, Arabidopsis; D000103:Acetyl-CoA Carboxylase
keywords: 
  Arabidopsis thaliana
  ; acetyl-CoA carboxylase; fatty acid metabolism; gene expression; map-based cloning; metabolic interaction