Biosynthesis and degradation of glycerides in external mycelium of Glomus mosseae

The activities of enzymes involved in the glyceride metabolism of Glomus mo sseae external mycelium are reported. Total mycelial homogenates were incub ated with radiolabeled triolein and palmitic acid for various times under d ifferent conditions. The results obtained demonstrate the capacity of G. mo sseae external mycelium to synthesize and hydrolyze its own acyl-glycerides . Neutral lipid biosynthesis progressively increased along with root coloni zation. Incorporation of [C-14]-palmitate was mainly into triacylglycerols and as a minor fraction into diacylglycerols. The activity of palmitoyl-CoA ligase in external mycelium also increased in parallel with mycorrhiza dev elopment. The hydrolysis of triacylglycerols was very low at the beginning of colonization and then increased. However, lipase activity was lower than that of acyl-CoA ligase even at late stages of colonization. Thus, triacyl glycerol biosynthesis apparently prevails over degradation during G. mossea e mycelium development in the period examined.