Biosynthesis and degradation of glycerides in external mycelium of <i>Glomus mosseae</i>

Abstract

The activities of enzymes involved in the glyceride metabolism of <i>Glomus mosseae</i> external mycelium are reported. Total mycelial homogenates were incubated with radiolabeled triolein and palmitic acid for various times under different conditions. The results obtained demonstrate the capacity of <i>G. mosseae</i> external mycelium to synthesize and hydrolyze its own acylglycerides. Neutral lipid biosynthesis progressively increased along with root colonization. Incorporation of [¹⁴C]-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 development. 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, triacylglycerol biosynthesis apparently prevails over degradation during <i>G. mosseae</i> mycelium development in the period examined.