Analysis of the subcellular localisation of lipoxygenase in legume and actinorhizal nodules

Plant Biol (Stuttg). 2012 Jan;14(1):56-63. doi: 10.1111/j.1438-8677.2011.00480.x. Epub 2011 May 17.

Abstract

Plant lipoxygenases (LOXs; EC 1.13.11.12) catalyse the oxygenation of polyunsaturated fatty acids, linoleic (18:2) and α-linolenic acid (18:3(n-3)) and are involved in processes such as stress responses and development. Depending on the regio-specificity of a LOX, the incorporation of molecular oxygen leads to formation of 9- or 13-fatty acid hydroperoxides, which are used by LOX itself as well as by members of at least six different enzyme families to form a series of biologically active molecules, collectively called oxylipins. The best characterised oxylipins are the jasmonates: jasmonic acid (JA) and its isoleucine conjugate that are signalling compounds in vegetative and propagative plant development. In several types of nitrogen-fixing root nodules, LOX expression and/or activity is induced during nodule development. Allene oxide cyclase (AOC), a committed enzyme of the JA biosynthetic pathway, has been shown to localise to plastids of nodules of one legume and two actinorhizal plants, Medicago truncatula, Datisca glomerata and Casuarina glauca, respectively. Using an antibody that recognises several types of LOX interspecifically, LOX protein levels were compared in roots and nodules of these plants, showing no significant differences and no obvious nodule-specific isoforms. A comparison of the cell-specific localisation of LOXs and AOC led to the conclusion that (i) only cytosolic LOXs were detected although it is generally assumed that the (13S)-hydroperoxy α-linolenic acid for JA biosynthesis is produced in the plastids, and (ii) in cells of the nodule vascular tissue that contain AOC, no LOX protein could be detected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinobacteria / physiology
  • Cyclopentanes / metabolism
  • Fabaceae / enzymology*
  • Fabaceae / metabolism
  • Fabaceae / microbiology
  • Frankia / physiology
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Plant
  • Lipoxygenase / metabolism*
  • Medicago truncatula / metabolism
  • Medicago truncatula / microbiology
  • Molecular Sequence Data
  • Nitrogen Fixation
  • Oxylipins / metabolism
  • Plant Growth Regulators / metabolism
  • Plant Roots / enzymology
  • Plant Roots / metabolism
  • Plant Roots / microbiology
  • Plastids / metabolism
  • Root Nodules, Plant / enzymology*
  • Root Nodules, Plant / metabolism
  • Root Nodules, Plant / microbiology
  • Sinorhizobium / physiology
  • Subcellular Fractions / enzymology
  • Subcellular Fractions / metabolism
  • Symbiosis / physiology
  • alpha-Linolenic Acid / biosynthesis

Substances

  • Cyclopentanes
  • Oxylipins
  • Plant Growth Regulators
  • alpha-Linolenic Acid
  • jasmonic acid
  • Lipoxygenase