Roles of a membrane-bound caleosin and putative peroxygenase in biotic and abiotic stress responses in Arabidopsis

Denis Murphy, Mark Partridge

Research output: Contribution to journalArticlepeer-review


ABSTRACT We report here the localisation and properties of a new membrane-bound isoform of caleosin and its putative role as a peroxygenase involved in oxylipin metabolism during biotic and abiotic stress responses in Arabidopsis. Caleosins are a family of lipid-associated proteins that are ubiquitous in plants and true fungi. Previous research has focused on lipid-body associated, seed-specific caleosins that have peroxygenase activity. Here, we demonstrate that a separate membrane-bound constitutively expressed caleosin isoform (Clo-3) is highly upregulated following exposure to abiotic stresses, such as salt and drought, and to biotic stress such as pathogen infection. The Clo-3 protein binds one atom of calcium per molecule, is phosphorylated in response to stress, and has a similar peroxygenase activity to the seed-specific Clo-1 isoform. Clo-3 is present in microsomal and chloroplast envelope fractions and has a type I membrane orientation with about 2 kDa of the C terminal exposed to the cytosol. Analysis of Arabidopsis ABA and related mutant lines implies that Clo-3 is involved in the generation of oxidised fatty acids in stress related signalling pathways involving both ABA and salicylic acid. We propose that Clo-3 is part of an oxylipin pathway induced by multiple stresses and may also generate fatty acid derived anti-fungal compounds for plant defence.
Original languageEnglish
Pages (from-to)796 - 806
Number of pages10
JournalPlant Physiology and Biochemistry
Issue number9
Publication statusPublished - 1 Jan 2009


  • abiotic stress
  • biotic stress
  • caleosin
  • oxylipins
  • peroxygenase
  • leptosphaeria maculans
  • salicylic acid


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