Genetic compensation of triacylglycerol biosynthesis in the green microalga Chlamydomonas reinhardtii

Thumbnail Image

Files

The Plant Journal - 2022 - Lee - Genetic compensation of triacylglycerol biosynthesis in the green microalga Chlamydomonas.pdf (2.45 MB)

Links to Files

https://onlinelibrary.wiley.com/doi/full/10.1111/tpj.15874

Permanent Link

https://doi.org/10.1111/tpj.15874
 http://hdl.handle.net/11603/25388

Collections

UMBC Biological Sciences Department
UMBC Department of Marine Biotechnology
UMBC Faculty Collection
UMBC Student Collection

Author/Creator

Author/Creator ORCID

https://orcid.org/0000-0001-7545-1883

Date

2022-06-21

Type of Work

journal articles
Text

Department

Program

Citation of Original Publication

Lee, Y.-Y., Park, R., Miller, S.M. and Li, Y. (2022), Genetic compensation of triacylglycerol biosynthesis in the green microalga Chlamydomonas reinhardtii. Plant J. https://doi.org/10.1111/tpj.15874

Rights

This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.
Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Subjects

Abstract

Genetic compensation has been proposed to explain phenotypic differences between gene knockouts and knockdowns in several metazoan and plant model systems. With the rapid development of reverse genetic tools such as CRISPR/Cas9 and RNAi in microalgae, it is increasingly important to assess whether genetic compensation affects the phenotype of engineered algal mutants. While exploring triacylglycerol (TAG) biosynthesis pathways in the model alga Chlamydomonas reinhardtii, it was discovered that knockout of certain genes catalyzing rate-limiting steps of TAG biosynthesis, type-2 diacylglycerol acyltransferase genes (DGTTs), triggered genetic compensation under abiotic stress conditions. Genetic compensation of a DGTT1 null mutation by a related PDAT gene was observed regardless of the strain background or mutagenesis approach, for example, CRISPR/Cas 9 or insertional mutagenesis. However, no compensation was found in the PDAT knockout mutant. The effect of PDAT knockout was evaluated in a Δvtc1 mutant, in which PDAT was upregulated under stress, resulting in a 90% increase in TAG content. Knockout of PDAT in the Δvtc1 background induced a 12.8-fold upregulation of DGTT1 and a 272.3% increase in TAG content in Δvtc1/pdat1 cells, while remaining viable. These data suggest that genetic compensation contributes to the genetic robustness of microalgal TAG biosynthetic pathways, maintaining lipid and redox homeostasis in the knockout mutants under abiotic stress. This work demonstrates examples of genetic compensation in microalgae, implies the physiological relevance of genetic compensation in TAG biosynthesis under stress, and provides guidance for future genetic engineering and mutant characterization efforts.