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Effects of eIF iso4G1 mutation on seed oil biosynthesis
Author(s) -
Li Qiang,
Shen Wenyun,
Zheng Qian,
Tan Yifang,
Gao Jie,
Shen Jinxiong,
Wei Yangdou,
Kunst Ljerka,
Zou Jitao
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13522
Subject(s) - biology , plastid , biochemistry , mutant , acetyl coa carboxylase , fatty acid , oleic acid , pyruvate carboxylase , fatty acid synthesis , biosynthesis , cytosol , gene , enzyme , chloroplast
Summary 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 eIF iso4G1. 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 (ht ACC ase) encoded by accD , were evident in the mutant. Biochemical assays showed that the developing seeds of the mutant possessed a decreased ht ACC ase activity in the plastid but an elevated activity of homomeric acetyl‐CoA carboxylase (hm ACC ase). These results suggested that the increased 20:1 was attributable at least in part to the enhanced cytosolic hm ACC ase activity. We also detected a significant repression of FATTY ACID DESATURASE 3 ( FAD 3 ) during seed development, which correlated with a decreased 18:3 level in seed oil. Together, our study on a mutant of eIF iso4G1 uncovered multifaceted interactions between the cytosolic and plastidic compartments in seed lipid biosynthesis that impact major seed oil traits.