Sucrose rescues seedling establishment but not germination of Arabidopsis mutants disrupted in peroxisomal fatty acid catabolism

Plant J. 2005 Sep;43(6):861-72. doi: 10.1111/j.1365-313X.2005.02498.x.


The Arabidopsis acyl-CoA oxidase (ACX) family comprises isozymes with distinct fatty acid chain-length specificities that together catalyse the first step of peroxisomal fatty acid beta-oxidation. We have isolated and characterized T-DNA insertion mutants in the medium to long-chain (ACX1) and long-chain (ACX2) acyl-CoA oxidases, and show that the corresponding endogenous activities are decreased in the mutants. Lipid catabolism during germination and early post-germinative growth was unaltered in the acx1-1 mutant, but slightly delayed in the acx2-1 mutant, with 3-day-old acx2-1 seedlings accumulating long-chain acyl-CoAs. In acx1-1 and acx2-1, seedling growth and establishment in the absence of an exogenous supply of sucrose was unaffected. Seedlings of the double mutant acx1-1 acx2-1 were unable to catabolize seed storage lipid, and accumulated long-chain acyl-CoAs. The acx1-1 acx2-1 seedlings were also unable to establish photosynthetic competency in the absence of an exogenous carbon supply, a phenotype that is shared with a number of other Arabidopsis mutants disrupted in storage lipid breakdown. Germination frequency of the double mutant was significantly reduced compared with wild-type seeds. This was unaffected by the addition of exogenous sucrose, but was improved by dormancy-breaking treatments such as cold stratification and after-ripening. We show that the acx1-1, acx2-1 and acx1-2 acx2-1 double mutants and the ketoacyl-CoA thiolase-2 (kat2) mutant exhibit a sucrose-independent germination phenotype comparable with that reported for comatose (cts-2), a mutant in a peroxisomal ABC transporter which exhibits enhanced dormancy. This demonstrates an additional role beyond that of carbon provision for the beta-oxidation pathway during germination or in dormant seeds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyl Coenzyme A / metabolism
  • Acyl-CoA Oxidase / genetics
  • Acyl-CoA Oxidase / physiology
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / physiology
  • Cyclopentanes / metabolism
  • Fatty Acids / metabolism*
  • Germination / drug effects*
  • Mutation
  • Oxylipins
  • Peroxisomes / genetics
  • Peroxisomes / metabolism
  • Seedlings / drug effects*
  • Sucrose / pharmacology*
  • Time Factors


  • Acyl Coenzyme A
  • Arabidopsis Proteins
  • Cyclopentanes
  • Fatty Acids
  • Oxylipins
  • Sucrose
  • jasmonic acid
  • ACX1 protein, Arabidopsis
  • ACX2 protein, Arabidopsis
  • Acyl-CoA Oxidase