HAPLOID PARTHENOGENETIC SPOROPHYTES OF LAMINARIA-JAPONICA (PHAEOPHYCEAE)

Parthenogenetic sporophytes were obtained from three strains of Lamina ria japonica Areschoug. These sporophytes grew to maturity in the sea, producing spores that all grew into female gametophytes. These female gametophytes gave rise to another generation of parthenogenetic sporo phytes during the next year, so that by the year 1990 parthenogenetic sporophytes had been cultivated for 12, 9, and 7 generations, respecti vely, for the three strains. When female gametophytes from parthenogen etic sporophytes were combined with normal male gametophytes, normal s porophytes that reproduced and gave rise to both female and male gamet ophytes were obtained. The parthenogenetic sporophytes were shorter an d narrower than the normal sporophytes of the same strain. Chromosome counts on mature sporophytes showed that normal sporophytes (from fert ilized eggs) were diploid (2n = approximately 40) and that the spores they produced were haploid (n = approximately 20), while nuclei from b oth somatic and sporangial cells in parthenogenetic sporophytes were h aploid. All gametophytes were haploid. Young sporophytes derived from cultures with both female and male gametophytes were diploid, while yo ung sporophytes obtained from female gametophytes from parthenogenetic sporophytes had haploid, diploid, or polyploid chromosome numbers. Po lyploidy was associated with abnormal cell shapes. The presence of hap loid parthenogenetic sporophytes should be of use in breeding kelp str ains with useful characteristics, since the sporophyte phenotype is ex pressed from a haploid genotype which can be more readily selected.