The discovery of the specific functions of different genes in alga Chlamydomonas reinhardtii, some of which are also present in plants, could allow for the advancement in technologies for engineering more climate-resilient plants or for enhancing biofuel production from algae.
Genes make up the blueprint that dictates the shape and structure of proteins and other biomolecules that are essential for life processes and that make up the unique physical characteristics of every living organism. However, most of their functions remain poorly documented and understood.
“Plant and algae genetics are understudied. These organisms make the foods, fuels, materials, and medicines that modern society relies on, but we have a poor understanding of how they work, which makes engineering them a difficult task,” said corresponding author Robert Jinkerson, an assistant professor of chemical and environmental engineering at UC Riverside. “A common way to learn more about biology is to mutate genes and then see how that affects the organism. By breaking the biology we can see how it works.”
To gain a better understanding of individual genes and the instructions they encode, a study by UC Riverside, Princeton University, and Stanford University was conducted to identify the specific functions of hundreds of genes in algae. Since plants and algae share some common genes, the findings from the study may be used to genetically modify plants to thrive in higher temperatures and algae to produce larger quantities of biofuel.
The researchers employed high-throughput methods to run experiments on thousands of samples of algal mutants of the species Chlamydomonas reinhardtii, a unicellular green alga that shares many of its genes with plants and is easily genetically modified. The automated approach was used due to its efficiency and ease of use for the collection of large amounts of data on a scale of the size of a genome. However, this approach was not directly utilised to study the function of genes in plants due to their physically larger sizes and increased genomic complexity.
The mutants were subjected to 121 different treatments, and their response to each treatment—some of which simulated environmental stressors—could be monitored by reading their unique DNA barcode, resulting in 16.8 million data points. Many new gene functions were found, some of which are also commonly found in other organisms, deepening the understanding of the functions of different genes.
Some discoveries include associating a gene prevalent in many multicellular organisms with its function of repairing DNA damage, as well as the identification of another set of 38 genes that are responsible for ensuring the proper harnessing of light energy for the first stage of photosynthesis. Other groups of genes were identified to have crucial functions like ensuring that the Calvin cycle is carried out properly, allowing for the production of glucose from carbon dioxide.
Other genes in the algae were also found to exert protective effects from toxins that inhibit cytoskeleton growth. Since some of these genes are also shared with plants, this discovery could allow for the bioengineering of more resilient plants that can thrive in contaminated soils.
“The data and knowledge generated in this study is already being leveraged to engineer algae to make more biofuels and to improve environmental stress tolerance in crops,” said Jinkerson.
The enhanced understanding of algae genetics has also been leveraged to modify algae to increase biofuel yields. The discoveries of different gene functions in algae are relevant to plants, so the information gained from this study would be useful for scientists to figure out how to genetically modify plants to be more tolerant of cold, heat, or temperature stress, or improve the efficiency of photosynthesis. This would be of increasing relevance to ensuring food security in a world where crop yields are increasingly threatened by climate change.
Source: Fauser et al. (2022). Systematic characterization of gene function in the photosynthetic alga Chlamydomonas reinhardtii.Nature Genetics, 54, 705–714.