Approach

Project Overview

Kelp life cycle informs breeding

Giant kelp is a large brown alga that creates marine forests in coastal areas of the northeast Pacific. Its growth rate and productivity are impressive, reaching 60 cm (2 feet) a day. The life cycle of kelp has two distinct phases, the macroscopic stage that we associate with the idea of a kelp forest (called the sporophyte because it produces dispersing spores), and a microscopic stage where male and female gametophytes, originating from spores, reproduce sexually to regenerate the sporophyte. The gametophytes are haploid (one copy of each chromosome) while the sporophytes are diploid (formed by the union of male and female gametes). Under controlled environmental conditions, it is possible to propagate the haploid gametophyte clonally and generate unlimited stock of identical male and female gametes. With this approach one can control which genetic material is used to create farmed sporophytes and facilitate the study of genotype-phenotype associations.

1) Mature sporophyte (2N), 2) meiotic zoospores (1N), 3) haploid gametophytes, 4) sexual reproduction between a gametophyte-borne egg and sperm, and 5) re-established diploidy in the juvenile sporophyte.

Individual gametophytes from across Giant Kelp's geographic range are maintained long-term in reduced light and nutrient conditions.

Gametophytes can be stored indefinitely in germplasm banks

By placing gametophytic tissue in a low nutrient, low light environment, these tissues can be stored long-term; the tissues will stay alive for nearly a year without any additional nutrients or media. This method is an attractive alternative to cryopreservation because the tissues are immediately useable for cultivation or manipulation studies and has optimal survival rates. Germplasm banks also allow storage of prioritized strains for various applications and industries.

Germplasm banks facilitate in vitro strain cultivation

One of the most important factors of optimizing macroalgal strains for industry is having knowledge of their parentage and genotype. With our germplasm bank of over 600 individuals, we can track desirable traits in the mature sporophytes back to the strain itself and their parental genotypes. This will ultimately facilitate identifying genetic traits that influence key sporophyte traits, like size, growth rate, and sugar (polysaccharide) profile - traits that are all important in strain selection for industry applications.

Female gametophytes settle on seed string in 3D printed plate; once they are fertilized by the male, a juvenile sporophyte begins to develop on the string.

Juvenile Giant Kelp sporophytes cultivated on seed string.

Sporophytes cultivated on string can be interwoven with long lines in oceanic farms

Once sporophytes are visible, they are outplanted in oceanic farms to grow in vivo. The seed string is interwoven with larger rope, which is then attached to a long line ~8 m below the sea surface.

Once they reach maturity, the sporophytes are ready to be harvested, phenotyped, and genotyped. The results of the first harvest will inform the strains prioritized for subsequent outplantings. Once strains have been well developed and characterized, they can be marketed for various applications across disciplines and uses.