Biology subjects

Weits, D. A.

Publications and source records attributed to Weits, D. A..

3 recordsLinked to original sources

bioRxiv2025

Progressive oxygenation of developing leaves directs morphogenesis

Oxygen availability underpins energy production in multicellular organisms, yet internal oxygen gradients arise in both plants and animals. Plants sense these variations via the PLANT CYSTEINE OXIDASE branch of the N-degron pathway, which regulates the stability of key transcription factors. Originally linked to metabolic control, this pathway recently emerged as a development regulator. While the shoot apical meristem was shown to be hypoxic, the oxygen dynamics of organs originating from this low-oxygen niche remain unknown. Here we show that developing leaves form a spatiotemporal oxygen gradient that is sensed through the oxygen sensing machinery. This pathway integrates local oxygen availability to regulate leaf morphogenesis: early hypoxia restricts cell expansion, while subsequent distal-to-proximal oxygenation enables specialized cell fates acquisition. Our findings reveal that oxygen acts as a positional cue in normal growth, guiding developmental trajectories. Our work highlights opportunities to harness oxygen gradients or sensing to direct plant form and function.

plant biology↗

bioRxiv2025

Hypoxia-activated fluorescent probes as markers of oxygen levels in plant cells and tissues

O_LILow oxygen signalling in plants is important in development and stress responses. Measurement of oxygen levels in plant cells and tissues is hampered by a lack of chemical tools with which to reliably detect and quantify endogenous oxygen availability. We have exploited hypoxia-activated fluorescent probes to visualise low oxygen (hypoxia) in plant cells and tissues. C_LIO_LIWe applied 4-nitrobenzyl (4NB-) resorufin and methyl-indolequinone (MeIQ-) resorufin to Arabidopsis thaliana whole cells and seedlings exposed to hypoxia (1% O2) and normoxia (21% O2). Confocal microscopy and fluorescence intensity measurements were used to visualise regions of resorufin fluorescence. C_LIO_LIBoth probes enter A.thaliana whole cells and are activated to fluoresce selectively in hypoxic conditions. Similarly, incubation with A.thaliana seedlings resulted in hypoxia-dependent activation of both probes and observation of fluorescence in hypoxic roots and leaf tissue. MeIQ-Resorufin was used to visualise endogenous hypoxia in lateral root primordia of normoxic A.thaliana seedlings. C_LIO_LIOxygen measurement in plants until now has relied on invasive probes or genetic manipulation. Use of these chemical probes to detect applied and endogenous hypoxia has the potential to facilitate a greater understanding of oxygen dynamics in plant cells and tissues, allowing correlation of oxygen concentrations with adaptive and developmental responses to hypoxia. C_LI

plant biology↗

bioRxiv2020

Acquisition of hypoxia inducibility by oxygen sensing N-terminal cysteine oxidase in spermatophytes

N-terminal cysteine oxidases (NCOs) are enzymes that use molecular oxygen to oxidize the amino-terminal cysteine of specific proteins, thereby initiating the proteolytic N-degron pathway and thus conferring them oxygen-dependent instability. To expand the characterization of the plant family of NCOs (PCOs), we performed a phylogenetic analysis across different plant taxa in terms of sequence similarity and transcriptional regulation. Based on this survey, we propose a distinction of PCOs into two main groups: A-type and B-type sequences. A-type PCOs are conserved across all plant species and are generally unaffected at the mRNA level by oxygen availability. Instead, B-type PCOs differentiated in spermatophytes to acquire specific amino acid features and transcriptional regulation in response to hypoxia. Both groups of PCO proteins possess the ability to destabilize Cys-initiating proteins. Indeed, the inactivation of two A-type PCOs in Arabidopsis thaliana, PCO4 and PCO5, is sufficient to activate, at least partially, the anaerobic response in young seedlings, whereas the additional removal of B-type PCOs leads to a stronger induction of anaerobic genes and impairs plant growth and development. Our results show that both PCO types are required to regulate the anaerobic response in angiosperm. Therefore, while it is possible to distinguish two clades within the PCO family, separated by both amino acid features and transcriptional regulation, we conclude that they both contribute to restrain the anaerobic transcriptional program in normoxic conditions and together generate a molecular switch to toggle the hypoxic response in Arabidopsis.One sentence summary Hypoxic induction of Plant Cysteine Oxidases has been acquired and fixed in seed plants by ancestor proteins able to initiate the proteolysis of Cys-initiating protein substrates by the Arg/N-degron pathway.View Full Text

plant biology↗