Medicago truncatula ENOD11: a novel RPRP-encoding early nodulin gene expressed during mycorrhization in arbuscule-containing cells

Mol Plant Microbe Interact. 2001 Jun;14(6):737-48. doi: 10.1094/MPMI.2001.14.6.737.

Abstract

Leguminous plants establish endosymbiotic associations with both rhizobia (nitrogen fixation) and arbuscular mycorrhizal fungi (phosphate uptake). These associations involve controlled entry of the soil microsymbiont into the root and the coordinated differentiation of the respective partners to generate the appropriate exchange interfaces. As part of a study to evaluate analogies at the molecular level between these two plant-microbe interactions, we focused on genes from Medicago truncatula encoding putative cell wall repetitive proline-rich proteins (RPRPs) expressed during the early stages of root nodulation. Here we report that a novel RPRP-encoding gene, MtENOD11, is transcribed during preinfection and infection stages of nodulation in root and nodule tissues. By means of reverse transcription-polymerase chain reaction and a promoter-reporter gene strategy, we demonstrate that this gene is also expressed during root colonization by endomycorrhizal fungi in inner cortical cells containing recently formed arbuscules. In contrast, no activation of MtENOD11 is observed during root colonization by a nonsymbiotic, biotrophic Rhizoctonia fungal species. Analysis of transgenic Medicago spp. plants expressing pMtENOD11-gusA also revealed that this gene is transcribed in a variety of nonsymbiotic specialized cell types in the root, shoot, and developing seed, either sharing high secretion/metabolite exchange activity or subject to regulated modifications in cell shape. The potential role of early nodulins with atypical RPRP structures such as ENOD11 and ENOD12 in symbiotic and nonsymbiotic cellular contexts is discussed.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Fabaceae / anatomy & histology
  • Fabaceae / genetics*
  • Fabaceae / microbiology
  • Fabaceae / physiology
  • Fungi / physiology*
  • Gene Expression Regulation, Fungal
  • Gene Expression Regulation, Plant
  • Membrane Proteins*
  • Molecular Sequence Data
  • Nitrogen / metabolism
  • Plant Proteins / genetics*
  • Plant Proteins / isolation & purification
  • Plant Roots / anatomy & histology
  • Plant Roots / microbiology
  • Plant Roots / physiology
  • Plant Tumors / etiology
  • Plants, Genetically Modified
  • Plants, Medicinal*
  • Plasmids
  • Sinorhizobium meliloti / physiology*
  • Symbiosis / physiology*

Substances

  • ENOD11 protein, Medicago truncatula
  • ENOD12 protein, Pisum sativum
  • ENOD7 protein, Pisum sativum
  • MTN6 protein, Medicago truncatula
  • Membrane Proteins
  • Plant Proteins
  • nodulin
  • Nitrogen