Hyphal Cell Wall Structure of Two Species of Pythium

Abstract

Hyphal cell walls were prepared by ultrasonication. Glucose was the only sugar detected in both species. Evidence was obtained indicating that the Pythium butleri Subram. glucan is beta 1,2-linked, and that the glucan of Pythium myriotylum Drechsler is beta 1,4-linked. Sixteen amino acids were detected in P. butleri cell wall hydrolysates. Four of these amino acids were absent from P. myriotylum preparations. Similar quantities of lipid were found in both species. The significance of these data for fungal classification is discussed.

Cell Wall Chemistry, Morphogenesis, and Taxonomy of Fungi

“…The cell wall glucan of Pythium bzttleri was claimed to be a pl,2-linked polymer analogous to the crown-gall polysaccharide of Agrobacterium tume faciens, mainly on the basis of partial similarity in X-ray reflections (49).…”

“…CELLULOSE-GLUCAN Recent papers described the structure of hyphal walls of Oomycetes of the orders Saprolegniales and Peronosporales with two phytopathogenic gen era, Phytophthora and Pythium, receiving the most attention. Except for a questionable claim(49), there is agreement on the similarity of wall com position among these fungi. Traditionally, the Oomycetes have been re garded as the cellulosic fungi; surprisingly, cellulose was found not to be the major component of the hyphal walls of any of the examined genera: Phytophthora(7,17,50), Pythimn(17,51), Achlya(42,50), Saprolegnia(17,42), Atkillsiella (50), Brevilegnia, or Dictyuchus(42).…”

Autolytic Enzymes in Fungal Cell Walls

“…These two pythium species have been shown to contain a glucan as the only polysaccharide. P. butleri glucan was found to be / 3 12 linked, whereas the linkage of P. myriotylum was /3 14 (Mitchell & Sabar, 1966).…”

“…During studies of the chemical structure of pythium cell walls (Mitchell & Sabar, 1966) it was observed that large quantities of glucose were released in control tubes containing cell walls alone during incubation a t 3 7 ' . These observations suggested a tendency of the mycelium of this fungus to undergo autolysis.…”

“…Bacterial lysis of pythium has been investigated in our laboratory (Mitchell & Hurwitz, 1965). During these investigations preparations were made of fungal cell walls and evidence was obtained which suggested that autolytic enzymes were active in the cell-wall preparations (Mitchell & Sabar, 1966). This report will describe the action of autolytic enzymes on Pythium cell walls.…”