Cell Surfaces in Plant-Microorganism Interactions

Ethylene production and cell wall hydroxyproline-rich glycoprotein (HRGP) biosynthesis are greatly enhanced in melon (Cucumin melo cv. Cantaloup charentais) seedlings infected with Colletotrichum lagenarium. Short-term experiments performed in the presence of specific inhibitors of the ethylene pathway from methionine, namely l-canaline and amino-ethoxyvinylglycine, indicate that under non-toxic conditions, both ethylene and [(14)C]hydroxyproline deposition in the cell wall of infected tissues are significantly lowered. On the contrary, treatment of healthy tissues with 1-aminocyclopropane 1-carboxylic acid, a natural precursor of ethylene, stimulates both the production of the hormone and the incorporation of [(14)C]hydroxyproline into cell wall proteins.The data provide the first evidence of the in vivo effect of ethylene on the cell wall hydroxyproline-rich glycoprotein biosynthesis in plants.