Natural variance in salt tolerance and induction of starch accumulation in duckweeds

MAIN CONCLUSION : Ten of 34 tested duckweed clones showed relatively higher salt tolerance. Salinity stress induced high level of starch accumulation in these clones, making them potential feedstock candidates for biofuel production. Duckweeds are promising as a new generation of crop plants that requires minimal input while providing fast biomass production. Two important traits of interest that can impact on the economic viability of this system are their sensitivity to salt and the starch content of the harvested duckweed. We have surveyed 33 strains of duckweed selected from across all 5 genera and amongst 13 species to quantify the natural variance of these traits. We found that there are large ranges of intraspecific variations in salt tolerance, while all species examined accumulated more starch in response to the initial stages of salt stress. However, the magnitude of the change in starch content varied widely between strains. Our results suggest that specific duckweed clones can be cultivated under relatively saline conditions, while increasing salt in the medium before harvesting could be used to increase starch in duckweed biomass for bioethanol production.