# Genome-Wide Characterization and Expression Analysis of CYP450 Genes in Chlamydomonas reinhardtii P.A. Dang

## TL;DR

This study identifies 37 Cytochrome P450 genes in the green alga Chlamydomonas reinhardtii and shows how they help the algae survive under environmental stress.

## Contribution

The study provides the first genome-wide characterization of CYP450 genes in Chlamydomonas reinhardtii, including their expression under stress conditions.

## Key findings

- 37 CYP450 genes were identified and mapped in C. reinhardtii, distributed across 12 chromosomes.
- Distinct groups of CYP450 genes are activated under specific stress conditions like salt or iron deficiency.
- CYP450 genes contain multiple introns and conserved motifs, with expression patterns grouped into nine clusters under stress.

## Abstract

Enzymes are essential for life processes in all organisms. One specific family of enzymes, known as Cytochrome P450, plays a critical role in helping plants and animals synthesize essential compounds and defend against environmental stress. However, scientists currently possess limited knowledge about these enzymes in Chlamydomonas reinhardtii, a single-celled green alga widely used as a model for biological research. This study aimed to identify all the Cytochrome P450 genes in this alga and investigate how they function under stress. We identified 37 specific genes and mapped their physical characteristics and locations within the cell. By exposing the algae to harsh conditions—including high salt, intense light, low temperature, and nutrient shortages—we discovered that these genes become highly active to help the algae survive. Specifically, we found that distinct groups of genes are triggered by different threats, such as iron deficiency or salt stress. These findings are valuable to society because they reveal the genetic mechanisms algae use to withstand environmental challenges. These insights provide a crucial foundation for future strategies to improve algal stress resilience, facilitating their broader application in sustainable biotechnology.

Cytochrome P450 (CYP450) monooxygenases are a class of enzymes containing conserved heme-binding functional domain. They contribute to a wide range of biosynthetic processes, serving a pivotal function in plant resistance to abiotic stress. To date, little is known about the CYP450s of Chlamydomonas reinhardtii. In our study, a total of 37 crP450 genes were identified from C. reinhardtii based on domain and sequence alignment, unevenly distributed on 12 chromosomes with 4 pairs of tandem replications shared among family members. Most of these genes contained 10 or more introns and encoded CYP450 proteins with an average of 593 amino acids and 3–9 conserved motifs. CYP450 enzymes were mainly distributed in the chloroplasts, cytoplasms, mitochondria, and cytoplasmic membranes. There were numerous light, jasmonic acid, abscisic acid, and salicylic acid response elements located in the upstream of gene coding sequences, suggesting that these genes could be modulated by plant hormones. Transcriptome analysis uncovered distinct expression patterns of crP450 genes under various stress conditions, with the 37 crP450 genes grouped into 9 clusters. In summary, this study presented a genome-wide characterization of CYP450 genes in C. reinhardtii, providing a strong foundation for further exploration into their biological functions.