Examining how CYP72A9 confers stress resilience in Arabidopsis thaliana

Abstract

Rapid climate change has caused more severe environmental stressors, such as increasing heat, higher heavy metal concentrations in soil, and drought. In response, plants have evolved defensive mechanisms with growth trade offs. Cytochrome P450s (CYPs) are ancient, diverse enzymes, especially abundant in plants, that play key roles in defense against pathogen infection, hormonal signaling, communication with other organisms, structural biosynthesis, and stress tolerance (Minerdi et al. 2023). The CYP72A subfamily includes enzymes that are induced by environmental stress that contribute to the broad secondary metabolism of foreign or toxic compounds (Prall et al. 2016). Genes for CYP72As are found in all sequenced flowering plants, but their biochemical activities vary widely, making them strong candidates for supporting stress responses unique to each plant's environment (Prallet al. 2016). CYP72A9 and homologs convert bioactive gibberellins (GA4) into a less active form of the hormone GA1 reducing growth (He et al. 2019). We hypothesize that overexpression of CYP72A9 confers a resilience to stress as part of the growth reduction and stress acclimation response. Each plant has 8-12 genes encoding CYP72A enzymes (Prall et al. 2016); only some CYP72As show GA inactivating activity (He et al. 2019, 2020). There should be sequence and structure similarities between the CYP72As that inactivate GAs. We hypothesize that there should be signature amino acids that confer to GA inactivation functionality to CYP72A9 and homologs.