Current status and perspectives of genome editing technology for microalgae

Abstract

Genome editing techniques are critical for manipulating genes not only to investigate their functions in biology but also to improve traits for genetic engineering in biotechnology. Genome editing has been greatly facilitated by engineered nucleases, dubbed molecular scissors, including zinc-finger nuclease (ZFN), TAL effector endonuclease (TALEN) and clustered regularly interspaced palindromic sequences (CRISPR)/Cas9. In particular, CRISPR/Cas9 has revolutionized genome editing fields with its simplicity, efficiency and accuracy compared to previous nucleases. CRISPR/Cas9-induced genome editing is being used in numerous organisms including microalgae. Microalgae have been subjected to extensive genetic and biological engineering due to their great potential as sustainable biofuel and chemical feedstocks. However, progress in microalgal engineering is slow mainly due to a lack of a proper transformation toolbox, and the same problem also applies to genome editing techniques. Given these problems, there are a few reports on successful genome editing in microalgae. It is, thus, time to consider the problems and solutions of genome editing in microalgae as well as further applications of this exciting technology for other scientific and engineering purposes.

Advances and challenges in genetic engineering of microalgae

“…CRISPR appears to be most efficient in microalgal genome editing based on the number of papers reported so far, even though it debuted last in the genome editing field (Jeon et al . ; Liang et al . ).…”

“…CRISPR appears to be most efficient in microalgal genome editing based on the number of papers reported so far, even though it debuted last in the genome editing field (Jeon et al 2017;Liang et al 2018). C. reinhardtii was the first microalgal genome edited with CRISPR-Cas9 technology .…”

Tailoring Microalgae for Efficient Biofuel Production

“…These genome editing tools induce doublestrand breaks at a specific locus in the genome, which get repaired through the non-homologous end joining machinery of the DNA repair process and introduce insertions or deletions at sites creating frameshift mutations (Gan and Maggs, 2017). Among the genome editing tools, CRISPR/Cas9 has gained much focus because of its simple, accurate, and efficient nature of operation (Jeon et al, 2017). In the CRISPR/Cas9 system, the Cas9 nuclease is directed by a single guide RNA (sgRNA) molecule, which binds to the target site in the genome following simple base-pairing rules.…”

Development and characterization of a Nannochloropsis mutant with simultaneously enhanced growth and lipid production

“…Despite these advantages, microalgae-based biofuels have drawbacks in terms of commercialization because of their high production cost. In this respect, the genetic and metabolic engineering of microalgae are being actively pursued to improve lipid production, which can contribute to reduced biofuel prices [6][7][8][9]. Strain development has focused on the overexpression of metabolic enzymes related to lipid biosynthesis [10][11][12][13][14] and transcriptional regulators [15][16][17][18], or the targeted mutagenesis of competitive pathways of lipid biosynthesis using TALEN, RNAi, and CRISPR/Cas9 techniques [19][20][21][22].…”