Genetics of Gracilaria tikvahiae (Rhodophyceae). VIII. Phenotypic and genetic characterization of some selected morphological mutants

Abstract

Morphological mutants of the marine red alga Gracilaria tikvahiae have been isolated in an initial attempt to develop improved strains for mariculture by selection of plants with altered growth habits. Both spontaneous and ethylmethanesulphonate-induced mutants were collected for this study. The phenotypes of the mutants range from plants with extremely fine, highly branched fronds to plants with thick puffy fronds. Among 10 mutants selected for more detailed study, 9 have distinctly different phenotypes. Genetic results identify nine mutant cistrons corresponding to the nine phenotypes. All the phenotypes are transmitted as single, mostly recessive, Mendelian mutations, with possible linkage appearing in two combinations of mutants. Growth trials in culture indicate that at least some of the mutants grow better than a genetically related wild type. In general, plants with increased branching showed the greatest promise.