DEVELOPMENTAL ASPECTS OF DALDINIA
Bayliss-Elliott (1920) provided some of the gross
features of stromatal development, including ring formation. Perithecial development has
apparently not been studied in great detail, but Ingold (1954) described the ascogenous
system. It is extensive, the nonseptate ascogenous hyphae elongating via fusions of
crozier ultimate and antepenultimate cells. The young perithecium is eventually
criss-crossed with ascogenous hyphae in a basket-weave fashion (Ingold, 1954).
Ascospores of D. concentrica have a hyaline dehiscent outer wall or perispore. This feature was probably first noted by Molliard (1904) and has been noted by several other authors. Beckett (1976a, 1976b) provided microscopic and ultrastructural details on dormant and germinating ascospores of D. concentrica. Ascospores of D. concentrica are uninucleate when formed and become binucleate via a mitotic division (Rogers, unpublished). One of the two nuclei then disintegrates; maturing ascospores are uninucleate. Nuclear behavior in ascospores of D. concentrica thus resembles that reported in several Hypoxylon species (Ju and Rogers, 1996; Rogers, 1979).
The anamorph of Daldinia species, where known, is referable to Nodulisporium Preuss. Tulasne and Tulasne (1863) illustrated the anamorph of D. concentrica and noted its occurrence on young stromata. Bayliss-Elliott (1920) found conidia only on very small and immature stromata. Molliard (1904) did an extensive study of the anamorph of D. concentrica and Panisset (1929) also dealt with it. The latest description of Daldinia anamorphs is that of Petrini and Müller (1986). In any case, it is well-known that the anamorph is not confined to young stromata in nature, but is often produced extensively on woody substrates.
Essentially nothing is known about the genetics of Daldinia species. Sharland and Rayner (1986) believe that results from cultural experiments indicate a mycelial recognition system in D. concentrica similar to those governing mating in heterothallic Basidiomycetes. In Daldinia, however, a stable secondary mycelium is not produced.