Restriction enzyme analysis of variation and taxonomy in the kelp genus Laminaria (Laminariales,Phaeophyta)

High levels of phenotypic variation in kelp species necessitate the use of taxonomic markers that are independent of morphology. Restriction fragment length polymorphism (RFLP) analysis of nuclear DNA can provide such markers. In this paper we present the results of an RFLP analysis of cytoplasmic ribosomal DNA (rDNA) in three Laminaria species (L. agardhii, L. digitata, L. groenlandica). Comparison of the restriction maps of the nontranscribed spacer (NTS) in the rDNAs suggests that this method should be useful for the differentiation of these taxa. These results are discussed, as are the applications of RFLP mapping to the identification of field-collected, morphologically variable plants.