Biology subjects

Lavilla-Puerta, M.

Publications and source records attributed to Lavilla-Puerta, M..

4 recordsLinked to original sources

bioRxiv2025

Anatomy and habitat shape the oxygen sensing machinery of angiosperms

Hypoxia sensing via the Cys/Arg branch of the N-degron pathway (Cys-NDP) is central for flooding responses in plants, yet how evolutionary and ecological factors have shaped the core oxygen sensing mechanism remains poorly understood. Leveraging the publication of multiple angiosperm genomes, we systematically analysed known Cys-NDP components in 55 angiosperms spanning aquatic, epiphytic, xerophytic, and mesophytic lineages. We also complemented this survey with hypoxia profiling and transcriptomic analyses in a selected panel of plants. This comparative effort revealed variation in Cys-NDP components, with Plant Cysteine Oxidases (PCOs) and group VII Ethylene Response Factors (ERFVIIs) emerging as major sources of diversification. Aquatic monocots displayed complete loss of A-type PCOs and dramatic expansion of a novel clade of ERFVIIs (HREaqua), frequently accompanied by loss or modification of the Cys-degron, uncoupling them from oxygen-dependent turnover. By contrast, xerophytes and epiphytes retained core Cys-NDP elements but showed shared hypoxia-induced gene expression, suggesting endogenous developmental or metabolic pressures for pathway conservation in habitats with limited flooding risk. Across all species, we identified a conserved transcriptional core of 11 orthogroups, including fermentation enzymes and regulatory factors, highlighting the early recruitment of these genes to hypoxia responses. Functional assays confirmed contributions of conserved MYB and LBD transcription factors to hypoxia tolerance in Arabidopsis. Together, our results demonstrate that both habitat and anatomy influence the evolution and deployment of oxygen-sensing networks in angiosperms. While persistent submergence promoted diversification of ERFVIIs and PCOs, retention of the core pathway across lineages points to fundamental roles in coping with endogenous oxygen gradients and fluctuations.

plant biology↗

bioRxiv2025

A synthetic ERFVII-dependent circuit in yeast sheds light on the regulation of early hypoxic responses of plants

Plants face hypoxic conditions either chronically, as particular tissues are characterized by fluctuating or stable low oxygen levels, or acutely, when flooded. In vascular plants, transcriptional adaptive responses to hypoxia are rapidly mounted by Ethylene Response Factors VII (ERFVIIs), regulated by Plant Cysteine Oxidases (PCOs) through the cysteine branch of the N-degron pathway (Cys-NDP) for oxygen sensing. However, this relatively simple regulatory circuit, consisting of both constitutively expressed as well as hypoxia-inducible ERFVIIs and PCOs, interacts with diverse signalling cues and pathways invoked by hypoxia. To understand the share of the PCO-mediated oxygen sensing mechanism in the production of hypoxia responses, we insulated the PCO/ERFVII circuit from Arabidopsis thaliana and adapted it to Saccharomyces cerevisiae. Using a reporter gene to monitor the output of the circuit allowed us to compare the speed and amplitude of response to hypoxia in the engineered yeast and the source organism. Hypoxia triggered ERFVII stabilization both in Arabidopsis and yeast, leading to a similarly fast transcriptional response that was however larger in plants. A simple hypoxia-inducible feedback loop improved the amplitude of response in yeast, demonstrating the importance of this regulation in the endogenous PCO/ERFVII circuit. Finally, computational modelling of the yeast circuit enabled us to identify promoter competition and presence of hypoxia-inducible PCOs as key parameters that shape early hypoxia responses in plant cells. Significance StatementWe report the design, testing and optimisation of a synthetic molecular switch that activates gene expression in response to hypoxia in the yeast Saccharomyces cerevisiae. This is based on enzymes that consume molecular oxygen to regulate the stability of transcription factors in plant cells. By generating such a hybrid molecular device, we were able to demonstrate the efficacy of this hypoxia response strategy independently of the many ancillary components that affect gene regulation in plant cells. In this way, we were able to assess its activation dynamics, characterised by similarly fast induction of gene expression in both yeast and plants. Our approach also revealed the requirement of interlocked feedback loops to achieve the magnitude of gene induction measured in plants.

plant biology↗

bioRxiv2025

Manipulating plant oxygen sensing through NCO substitution reveals trade-offs between growth and flooding tolerance

The oxygen-dependent degradation of Ethylene Response Factors VII (ERFVIIs) through the N-degron pathway is central to regulating the transcriptional responses to hypoxia in vascular plants. Plant Cysteine Oxidases (PCOs) control this step by catalysing the oxidation of an N-terminal Cys residue exposed by ERFVIIs. In the present study, we investigated the functional impact of replacing Arabidopsis PCOs with diverse N-terminal cysteine oxidases (NCOs) from across the three eukaryotic kingdoms, hypothesizing that structural and kinetic differences may influence gene regulation of ERFVII targets under hypoxia and thus impact stress tolerance. Combining structural analyses, in vitro biochemical characterisation and in planta complementation assays we observed that not all tested NCOs are functionally equivalent to the endogenous PCOs. In fact, despite the remarkable conservation of catalytic motifs, we identified key differences in enzyme architecture that appear to affect the enzymes capacity to regulate hypoxia responses in plants. Notably, NCO efficiency in oxidising ERFVII peptides inversely correlated with hypoxic gene expression under aerobic conditions and enhanced submergence survival, suggesting that partial ERFVII stabilization primes plants to cope with hypoxia. However, enhanced basal expression of hypoxia-responsive genes in turn correlated negatively with development and biomass accumulation, pointing to a trade-off between growth and stress resilience. Our findings demonstrate that tuning NCO activity can reshape the transcriptional and physiological hypoxia response, suggesting it is possible to enhance plant resilience under fluctuating oxygen conditions through enzyme engineering and precision breeding. Significance statementControl of low oxygen responses to improve crop flooding tolerance is a long-sought objective of molecular plant breeders. The oxygen-dependent oxidation of N-terminal cysteines in transcription factors is thought to be a key step in modulating the transcriptional response to hypoxia. In this study, we tested this hypothesis by substituting endogenous N-terminal cysteine dioxygenases with homologues from different species characterized by highly divergent sequences, structures, and kinetic properties. We show that indeed these variations effectively and predictably influence gene transcription in plants exposed to hypoxia, thereby affecting their tolerance to submergence. However, we also demonstrate that, unexpectedly, these substitutions impact plant growth and development under aerobic conditions, revealing a trade-off between flooding stress resilience and biomass accumulation or yield.

plant biology↗

bioRxiv2024

H2O2 repurposes the plant oxygen-sensing machinery to control the transcriptional response to oxidative stress

Plants sense reduced oxygen availability (hypoxia) through Plant Cysteine Oxidases (PCOs). Reduced PCO activity in hypoxia, as seen during submergence, stabilises Group VII Ethylene Response Factors (ERFVIIs), master regulators of adaptive metabolic and anatomic responses. Equally important is timely arrest of these responses upon reoxygenation, assumed to occur through ERFVII degradation. Reoxygenation involves reactive oxygen species (ROS) production. Here, we report that instead of degradation, reoxygenation results in ERFVII nuclear stabilisation, an effect mimicked by direct H2O2 treatment. Interestingly, typical hypoxia marker genes are repressed while genes involved in ROS homeostasis and oxidative stress protection are upregulated. Using in planta, heterologous and biochemical assays, we reveal that ROS-related ERFVII stabilisation is caused by PCO inactivation. Stabilised ERFVIIs are retained at hypoxia-responsive promoters but become repressors. Our findings suggest that by responding to both oxygen and ROS, PCOs coordinate ERFVII stability to regulate timely responses to damaging fluctuations in oxygen availability.

plant biology↗