Biology subjects

De Zeeuw, T.

Publications and source records attributed to De Zeeuw, T..

4 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

CYP79B2 and CYP79B3 contribute to root branching through production of the auxin precursor indole-3-acetonitrile

Lateral root placement, outgrowth and density are influenced by environmental changes, including salinity stress. CYP79B2 and B3 are two cytochrome P450 enzymes previously identified as required for root architecture remodeling in salt. They produce iAOx, a metabolite that can be converted into indole glucosinolates (IGs), camalexin and indole-3-acetic acid (IAA), a type of auxin. We report here that lateral root appearance, induced by an auxin maximum in the bending zone after gravistimulation, is delayed in the absence of CYP79B2/B3. This delay traces back to a decrease in early lateral root growth after emergence, taking place before lateral roots are macroscopically visible. We measured gene transcripts and abundance of metabolites in the iAOx pathway in root segments that are forming lateral roots. Genes involved in tryptophane and IG biosynthesis were upregulated in cyp79b2/b3 mutants, suggesting a transcriptional feedback-loop. Salt stress was found to increase the expression of genes involved in IAN biosynthesis, a precursor of both IAA and camalexin, in the root during lateral root formation. Moreover, salt increases the concentration of IAN in tissue forming lateral roots in a CYP79B2/B3 dependent manner, but these changes in IAN did not coincide with altered IAA levels. Both the reduction in lateral root density under salt and the delayed lateral root appearance in cyp79b2/b3 knock-out mutants can be complemented by exogenous application of IAN. Our results reveal a role for the iAOx pathway in regulating the timing of lateral root appearance, allowing the modulation of lateral root density under salt stress.

plant 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↗