The relationship between rhythmic hyphal growth and circadian formation of sclerotia in Sclerotium rolfsii Sacc.

The mycelium of the phytopathogenic fungus Sclerotium rolfsii type R (ATCC 26326) grown on a solid medium supplemented with 70 mM l-threonine exhibits a synchronous formation of sclerotia in circles whereas both leading and lateral hyphae enter into a rhythmic growth rate. A rhythmic activity of malate synthetase (malate synthase, EC 4.1.3.2) which accompanied the hyphal rhythm and preceded the formation of sclerotial circles was demonstrated. Both translocation of L-[14C]threonine and incorporation of L-[14C]leucine were significantly related to the circadian formation of sclerotia.