Artificial hybridization between Ascophyllum nodosum and Fucus vesiculosus (Phaeophyceae) from Nova Scotia, Canada

Reciprocal crosses between male and female gametes of Ascophyllum nodosum (L.) LeJolis and Fucus vesiculosus L. were made from plants collected at Tor Bay, Nova Scotia. Crosses within each species were viable and resulted in normal zygote development. Hybrids occurred in low frequency in the cultures (ca. 1–5%) and developed either an initial rhizoid or underwent one or two internal divisions. Hybrid zygotes did not develop further. More developing embryos were observed in crosses when F. vesiculosus provided the eggs, and these zygotes developed longer rhizoids. Maximum development was to three or four cells, which occurred in ca. 10 days. By 5 weeks, all zygotes had disintegrated. Nuclear diameter was the same in both species (6 μm) although almost twice as much nuclear DNA was present in A. nodosum than in F. vesiculosus. Nuclei in hybrids were larger than in the parental species.