Light response in Phycomyces blakesleeanus: Evidence for roles of chitin biosynthesis and breakdown

L. Herrera-Estrella, J. Ruiz-Herrera

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Chitin synthetase activity, both basal and zymogenic, from Phycomyces sporangiophores was stimulated by light in vitro and in vivo. A madB mutant did not display these activations, whereas in a madE mutant only chitin synthetase zymogen was increased by illumination in vivo. Light also produced a transient alteration in cell wall structure at the apical region of the sporangiophore revealed by accessibility of chitin to binding by wheat germ agglutinin and by an increased limited breakage of chitin microfibrils. This last response was absent in both madB andmadE mutants. Accordingly, it is suggested that the light growth response in the sporangiophore from Phycomyces is due to a transient softening of the cell wall at the growing region followed by an elongation due to the turgor pressure of the cell and an enhanced chitin biosynthesis by the apically localized chitin synthetase which restores normal strength to the cell wall. A hypothetical scheme to account for these results is presented.

Original languageEnglish
Pages (from-to)362-369
Number of pages8
JournalExperimental Mycology
Volume7
Issue number4
DOIs
StatePublished - Dec 1983

Keywords

  • Phycomyces
  • chitin breakdown
  • chitin synthetase
  • photomecism
  • phototropism
  • wall structure

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