Functional Diversity of CYP79A Genes in Sorghum: Roles in Metabolism, Defense, and Adaptation

  • SorghumBase Team
  • 31 March 2025

This study explores the functional diversity of sorghum CYP79A genes, revealing their roles in amino acid metabolism, plant defense, growth regulation, and environmental adaptation.

Keywords: CYP79A, oximes, tissue-specific expression, plant signaling

In this collaborative study with Professor Mullets group we are happy to bring to life CYP79A genes in sorghum previously considered to be silent. In future studies we aim to study the functions of the individual CYP79A genes in sorghum taking advantage of the FIND-IT technology in producing  knoch-out variants of the individual CYP79A- genes. The SorghumBase is really helpful to us, e.g. by rapidly guiding us to new CYP79A mutants and updating us on exciting new discoveries from around the entire sorghum world. – Møller

In a publication in 2018 in Molecular Plant, we designated oximes and unrecognized chameleons in general and specialized plant metabolism. The  current study represents a step forward in the elucidation of their multiple functions in plants. I am really happy to be part  of this highly interdisciplinary study and happy that we were able to use a future crop plant as the experimental system instead of a model plant. – Sørensen

Scientists from University of Copenhagen and Texas A&M University investigated the functional diversity of CYP79A genes in sorghum, focusing on their role in amino acid metabolism and cyanogenic glucoside biosynthesis. While CYP79A1 is well-established as a key enzyme in dhurrin production, this research characterizes the functions of eight additional CYP79A genes. Phylogenetic analysis segregates these genes into two distinct clades. SbCYP79A61, a member of Clade A, shares  enzymatic similarities with maize orthologues, catalyzing the conversion of phenylalanine into phenylacetaldoxime. Functional assays reveal that Clade B members exhibit varied substrate specificities, with CYP79A91, CYP79A93 and CYP79A95 converting valine and isoleucine to their respective oximes, whereas CYP79A94 only converts isoleucine. CYP79As are involved in producing volatile oximes that may function in plant signaling and herbivore interactions. Further, CYP79A93 also converts phenylacetaldoxime, however, seembly to a lesser extent than SbCYP79A61. The expression of these genes is highly tissue-specific, with CYP79A61 predominantly expressed in mature leaves, hinting at a role in plant defense mechanisms. 

The study also suggests that CYP79A-derived oximes and their metabolic derivatives contribute to plant growth regulation, defense, and environmental adaptability. Expression patterns suggest potential involvement in root architecture, flowering regulation, and stress responses, such as drought tolerance. The presence of CYP79A genes in other monocots implies a broader evolutionary significance. Future studies using gene knockout techniques and yeast-based assays aim to further clarify their physiological roles. Overall, this research highlights the functional complexity of CYP79A enzymes beyond dhurrin biosynthesis, emphasizing their importance in sorghum’s adaptive strategies and metabolic networks.

SorghumBase examples: 

Figure 1: The authors aligned nine CYP79 genes from Sorghum bicolor, a cytochrome P450 family involved in specialized metabolism. Phylogenetic analysis of SORBI_3010G172200 reveals its evolutionary relationships with homologous genes across diverse plant species. Gene duplications and expansions within Sorghum bicolor are evident, with clusters of 2, 7, 29, and 41 genes, suggesting lineage-specific diversification. SORBI_3010G172200 shares evolutionary ties with rosids and Magnoliophyta, with Arabidopsis homologs (AT2G22330, AT4G39950) indicating potential functional conservation. The alignment overview (right panel) presents protein sequence alignments color-coded by InterPro domains, where blue blocks represent highly conserved regions, while sequence gaps and variations suggest divergence.
Figure 2: Taxonomic distribution under the Homology tab shows the SORBI_3010G172200 across 395 genes in 46 genomes which highlights its evolutionary conservation within Sorghum bicolor, closely related grasses (Zea mays, Oryza sativa), and more distantly related species (Arabidopsis thaliana, Vitis vinifera). The phylogenetic tree (left) illustrates these evolutionary relationships, while the right panel displays a multi-species sequence alignment with color-coded blocks representing conserved sequence regions. The observed variability suggests potential functional divergence of homologs across taxa.
Figure 3: This figure shows the expression profile of SORBI_3010G172200 under the Expression Tab (all paralogs) in SorghumBase. It displays the baseline expression across 4 experiments in different tissue types. The datasets are curated and processed by EMBL-EBI Expression Atlas in collaboration with the SorghumBase team.
Figure 4: The Germplasm tab displays predicted loss-of-function (LOF) alleles for SORBI_3010G172200 (Sb10g022470, Sobic.010G172200), which is similar to Cytochrome P450 79A1, across various germplasms. This tab lists accessions harboring protein-truncating variants (PTVs), including frameshift and stop-gained mutations. Each entry provides the predicted consequence, zygosity (homozygous or heterozygous), and the associated genotyping study in which the variant was identified. These PTVs represent putative LOF single nucleotide polymorphisms (SNPs) within the canonical transcript of the gene model. The closest annotated homolog in Arabidopsis thaliana is CYP79B2, which shares 48% identity.

Reference:

Koleva DT, Liu M, Dusak B, Ghosh S, Krogh CT, Hellebek IR, Cortsen MT, Motawie MS, Jørgensen FS, McKinley BA, Mullet JE, Sørensen M, Møller BL. Amino acid substrate specificities and tissue expression profiles of the nine CYP79A encoding genes in Sorghum bicolor. Physiol Plant. 2025 Jan-Feb;177(1):e70029. PMID: 39749417. doi: 10.1111/ppl.70029. Read more

Related Project Websites: 

Image 1: New variants in sorghum can be obtained using the FIND-IT approach (Knudsen et al., Science Advances, 8, eabq2266 (2022); Dockter et al., Plant Molecular Biology 22, 3051-3053 (2024). Illustration: Katja Annette Willrodt and Birger Lindberg Moller)
Image 2: Young sorghum plants in a field in Toowoomba, OLD, Australia. Photo credit Peter Stuart, Seedtek Pty Ltd.
Image 3: Sorghum plants in a field in Toowoomba, QLD, Australia Photo credit Peter Stuart, Seedtek Pty Ltd.
Image 4: Sorghum crop, Toowoomba, QLD, Australia Photo credit Peter Stuart, Seedtek Pty Ltd.