Biology subjects

Verstappen, F.

Publications and source records attributed to Verstappen, F..

5 recordsLinked to original sources

bioRxiv2024

Potato cultivars use different root physiological and molecular mechanisms to acclimate to salt stress

O_LISoil salinity induces osmotic stress and ion toxicity in plants, detrimentally affecting their growth and development. Potato (Solanum tuberosum) faces yield reductions due to salt stress. The mechanisms of salt stress resilience, especially in adventitious roots, remain unknown. C_LIO_LIWe investigated the resilience of three potato cultivars - Desiree, Innovator, and Mozart - by studying their physiological and transcriptomic responses to salt stress. C_LIO_LIOur findings reveal that under salt stress, the growth of stolons and stolon node roots is similarly reduced unlike tubers, even though they are physically connected. Surprisingly, tubers accumulate Cl- but not Na+ under salt stress, suggesting an active Na+ exclusion mechanism. Innovator showed the lowest suberin and lignin deposition before salt stress and higher K+ leakage, leading to a stronger initial stress response with high ABA content and a distinct transcriptomic pattern. Nevertheless, Innovator was the most resilient, displaying lower growth, salt-tolerance index and tuber yield reduction. Transcriptomic analysis revealed several K+/Na+ channel genes which might regulate ions homeostasis during salt stress, in particular in Innovator. C_LIO_LIAltogether, we conclude that acclimation ability, rather than initial protection of roots against salt, prevails in long term salt-stress resilience of potato. C_LI

plant biology↗

bioRxiv2023

Abscisic acid signaling gates salt-specific responses of plant roots

Soil salinity presents a dual challenge for plants, involving both osmotic and ionic stress. In response, plants deploy distinct yet interconnected mechanisms to cope with these facets of salinity stress. In this investigation, we observed a substantial overlap in the salt (NaCl)-induced transcriptional responses of Arabidopsis roots with those triggered by osmotic stress or the plant stress hormone abscisic acid (ABA), as anticipated. Notably, a specific cluster of genes responded uniquely to sodium (Na+) ions. Surprisingly, expression of sodium-induced genes exhibited a negative correlation with the ABA response and preceded the activation of genes induced by the osmotic stress component of salt. Elevated exogenous ABA levels resulted in the complete abolition of sodium-induced responses. Consistently, ABA signalling mutants displayed prolonged sodium-induced gene expression, coupled with increased root cell damage under high salinity conditions. Moreover, ABA signalling mutants were unable to redirect root growth to avoid high sodium concentrations and failed to contain their root cell swelling in the presence of elevated salt levels. In summary, our findings unveil an unexpected and pivotal role for ABA signaling in mitigating cellular damage induced by salinity stress and modulating sodium-specific responses in plant roots.

plant biology↗

bioRxiv2023

Warm temperature and mild water stress cooperatively promote root elongation

Warm temperatures have a dramatic effect on plant development. In shoots, stems elongate, and leaves are raised in a developmental programme called thermomorphogenesis. This results in enhanced leaf cooling capacity1. Thermomorphogenesis is tightly intertwined with light signalling pathways. The level of integration is so high that it has been proposed that shoot temperature sensing may have evolved from the co-option of an existing light signalling pathway during the colonisation of land by plants2. Roots also undergo thermomorphogenesis, but the mechanism by which this occurs is less well understood. Main root elongation is enhanced at warm temperatures, and this response is independent of many of the light and temperature signalling components of the shoot3. Roots develop in darkness and so it is a reasonable assumption that root temperature signalling is not through modulation of light signalling. It was recently speculated that due to the close correlation between warm temperature and soil moisture content, root temperature signalling could feasibly be related to water availability signals2. In this study we tested the interaction between temperature and water availability signalling in plant roots. We found that these environmental factors co-operatively enhance main root elongation. This interaction effect was dependent on SUCROSE NON-FERMENTING RELATED KINASE 2.2 (SnRK2.2) and SnRK2.3 and the E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). We found that SnRK2.2 / 2.3 and COP1 have opposite effects on the stability of the transcription factor ELONGATED HYPOCOTYL 5 (HY5) in elongation zone hair cells. The stability of HY5 in these cell types generally corresponded to the degree of root elongation seen in each mutant background. Our study reveals several molecular components of root thermomorphogenesis and highlights the importance of an integrative approach to plant environmental signalling. Our results may have direct implications for agricultural land management, especially as global climates become more unpredictable.

plant biology↗

bioRxiv2023

Natural gene variation in Cannabis sativa unveils a key region of cannabinoid synthase enzymes

Cannabinoids are well-known specialised metabolites from the plant Cannabis sativa L. (cannabis). They exhibit various therapeutical to intoxicating psychoactive effects and have potential for medicinal applications. Among the enzymes involved in cannabinoid biosynthesis, cannabinoid oxidocyclases such as the tetrahydrocannabinolic acid (THCA) synthase play a key role in determining cannabis chemotype. To improve our understanding of cannabinoid oxidocyclase structure-function relationship, we proposed a new approach to targeted mutagenesis. By reviewing cannabis natural variation, three cannabinoid oxidocyclase mutations (S355N, CONF, G376R) associated to atypical plant chemotypes were selected. In-vitro characterization of THCA synthase mutants demonstrated these mutations significantly impact enzyme activity, correlating with the associated chemotype: S355N nearly inactivated the THCA synthase, CONF impaired CBGA metabolization and altered product specificity, while G376R drastically reduced enzyme activity and altered product specificity. In-silico docking experiments permitted to model the successive steps of THCA synthase substrate metabolization, revealing that the three mutations hamper substrate binding. Collectively, our results demonstrated how plant diversity can be leveraged to guide enzyme targeted mutagenesis, highlighted a key region of cannabinoid oxidocyclases, and permitted the establishment of a new model of the THCA synthase catalytic mechanism. This provides new insights into enzyme function, which can ultimately help developing medicinal cannabis cultivars and cannabinoid biotechnological production.

molecular biology↗

bioRxiv2023

Root branching in salt requires auxin-independent modulation of LBD16 function

Salinity stress constrains lateral root (LR) growth and severely impacts plant growth. Auxin signaling is indispensable for the regulation of LR formation. Nevertheless, the molecular mechanism of how salinity affects root auxin signaling and whether salt would steer alternative pathway(s) to regulate LR development is unknown. Here we show that the auxin-regulated transcription factor LATERAL ORGAN BOUNDARY DOMAIN (LBD)16, known as an essential player for LR development under control conditions, is regulated by an alternative non-canonical pathway under salinity. Salt represses auxin signaling but in parallel activates an upstream transcriptional activator of LBD16, ZINC FINGER OF ARABIDOPSIS THALIANA 6 (ZAT6). ZAT6 modulates the activity of LBD16 to contribute to downstream cell wall remodeling, and promotes LR development under salinity stress. Our study thus shows that root developmental plasticity in response to salt stress is achieved by integration of auxin-dependent repressive and salt-activated auxin-independent pathways converging on LBD16 to modulate root branching modulation under salinity.

plant biology↗