Heritable variation in growth and biomass productivity in the clonal freshwater macroalga Oedogonium

In an analogous manner to which selective breeding and propagation of heritable traits have improved terrestrial crops, the directional selection of target strains of commercial algae produced through clonal propagation is essential to realising their full potential for biomass applications and develop cost effective production. As a first step towards establishing a trait selection programme in clonal freshwater macroalgae of the genus Oedogonium, we determined whether there is heritable variation in growth and biomass productivity in 6 genetically distinct strains. Intraclonal variability in growth was quantified within clonal lineages of single filaments in laboratory cultures, and intraclonal variability in biomass productivity was quantified within clonal lineages of intensive cultures containing multiple filaments maintained in outdoor cultures. We found significant estimates of genetic variance (Broad-sense heritability, H2: 0.16-0.51) in growth among clonal replicates of 4 strains in laboratory cultures, and significant estimates of genetic variance (H2 > 0.69) in biomass productivity in two strains in outdoor intensive cultures. These results demonstrate that there is an important heritable component to variation in growth and biomass productivities among theoretically identical clonal lineages for these strains. Such data is rare for freshwater macroalgae and suggest that growth and biomass productivity for these strains could be improved by maintaining selected clonal lines.