Antifungal activity of tobacco osmotin has specificity and involves plasma membrane permeabilization

Laura R. Abad, Matilde Paino D'Urzo, Dong Liu, Meena L. Narasimhan, Moshe Reuveni, Jian Kang Zhu, Xiaomu Niu, Narendra K. Singh, Paul M. Hasegawa, Ray A. Bressan

Research output: Contribution to journalArticlepeer-review


Osmotin protein is able to inhibit in vitro the growth of a number of unrelated pathogens. A survey of 31 isolates representing 18 fungal genera indicated that sensitivity may be determined at the genus level. Hyphal growth of Aspergillus flavus, Aspergillus parasitica, Rhizoctonia solani and Macrophomina phaseolina was highly resistant to osmotin whereas the growth of Bipolaris, Fusarium and Phytophthora species was very sensitive. Of all fungi tested Trichoderma longibrachiatum hyphal growth was most inhibited by osmotin treatment. Osmotin either induced sporelysis, inhibited spore germination or reduced germling viability in seven fungal species that exhibited some degree of sensitivity in hyphal growth inhibition tests. The species-specific growth inhibition was correlated with the ability of osmotin to dissipate the fungal membrane pH gradient. Both growth inhibition and pH gradient dissipation by osmotin were sensitive to NaCl and other inorganic cations. Cells of T. longibrachiatum were insensitive to osmotin after plasmolysis, suggesting that the cell wall may be a component of the mechanism by which osmotin permeabilizes the plasma membrane and kills fungal cells.

Original languageEnglish
Pages (from-to)11-23
Number of pages13
JournalPlant Science
Issue number1
StatePublished - 21 Jul 1996
Externally publishedYes


  • Antifungal protein
  • Fusarium sp.
  • Osmotin
  • Pathogenesis-related protein
  • Phytophthora sp.
  • Trichoderma longibrachiatum

ASJC Scopus subject areas

  • Genetics
  • Agronomy and Crop Science
  • Plant Science


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