Coumarin is a phytotoxic natural compound able to affect plant growth and development. Previous studies have demonstrated that this molecule at low concentrations (100 µM) can reduce primary root growth and stimulate lateral root formation, suggesting an auxin-like activity. In the present study, we evaluated coumarin’s effects (used at lateral root-stimulating concentrations) on the root apical meristem and polar auxin transport to identify its potential mode of action through a confocal microscopy approach. To achieve this goal, we used several Arabidopsis thaliana GFP transgenic lines (for polar auxin transport evaluation), immunolabeling techniques (for imaging cortical microtubules), and GC-MS analysis (for auxin quantification). The results highlighted that coumarin induced cyclin B accumulation, which altered the microtubule cortical array organization and, consequently, the root apical meristem architecture. Such alterations reduced the basipetal transport of auxin to the apical root apical meristem, inducing its accumulation in the maturation zone and stimulating lateral root formation.

trans-Cinnamic acid is a phenolic compound widely studied in plant metabolism due to its importance in regulating different plant processes. Previous studies on maize plants showed that this compound could affect plant growth and causes metabolic changes in the leaves when applied. However, its effects on root metabolism are not well known. This study analyses the short-term effect of trans-cinnamic acid on the morphology of vascular bundle elements and metabolism in maize roots. At short times (between 6 and 12 h), there is a reduction in the content of many amino acids which may be associated with the altered nitrogen uptake observed in earlier work. In addition, the compound caused an alteration of the vascular bundles at 48 h and seemed to have changed the metabolism in roots to favor lignin and galactose synthesis. The results obtained complement those previously carried out on maize plants, demonstrating that in the short term trans-cinnamic acid can trigger stress-coping processes in the treated plants.

Introduction: Peach (Prunus persica (L.) Batsch,) and nectarine fruits (Prunus persica (L.) Batsch, var nectarine), are characterized by a rapid deterioration at room temperature. Therefore, cold storage is widely used to delay fruit post-harvest ripening and extend fruit commercial life. Physiological disorders, collectively known as chilling injury, can develop typically after 3 weeks of low-temperature storage and affect fruit quality.Methods: A comparative transcriptomic analysis was performed to identify regulatory pathways that develop before chilling injury symptoms are detectable using next generation sequencing on the fruits of two contrasting cultivars, one peach (Sagittaria) and one nectarine, (Big Top), over 14 days of postharvest cold storage.Results: There was a progressive increase in the number of differentially expressed genes between time points (DEGs) in both cultivars. More (1264) time point DEGs were identified in ‘Big Top’ compared to ‘Sagittaria’ (746 DEGs). Both cultivars showed a downregulation of pathways related to photosynthesis, and an upregulation of pathways related to amino sugars, nucleotide sugar metabolism and plant hormone signal transduction with ethylene pathways being most affected. Expression patterns of ethylene related genes (including biosynthesis, signaling and ERF transcription factors) correlated with genes involved in cell wall modification, membrane composition, pathogen and stress response, which are all involved later during storage in development of chilling injury.Discussion: Overall, the results show that common pathways are activated in the fruit of ‘Big Top’ nectarine and ‘Sagittaria’ peach in response to cold storage but include also differences that are cultivar-specific responses.

Fucoxanthin is the predominant carotenoid in diatoms, playing a central role in light harvesting and photoprotection, and is increasingly valued for its potential in pharmaceutical, nutraceutical, and cosmetic applications. In this study, we investigated the influence of high nitrate supplementation, low-light exposure, and combined treatment, on fucoxanthin content and on the expression of key genes involved in its biosynthetic pathway in the marine diatom Thalassiosira rotula. Fucoxanthin content was quantified using HPLC-based and spectrophotometric methods. Control culture at the exponential growth phase showed a fucoxanthin content of 4.7 mg g⁻¹ DW, reaching 5.2 mg g⁻¹ DW under low-light conditions at the late exponential phase. Gene expression analysis revealed condition-dependent modulation of major biosynthetic genes (PSY, PDS, ZCIS, CRTISO, ZEP, VDL, DDE). Early biosynthetic genes, PSY and PDS, were upregulated under low light, whereas ZCIS and CRTISO responded to high nitrate availability. ZEP exhibited treatment-specific induction and VDL isoforms showed differential regulation, highlighting distinct xanthophyll cycle gene expression patterns across treatments. These results demonstrate that both light and nitrate availability modulate fucoxanthin content and biosynthetic gene expression in T. rotula, providing insights into the regulatory mechanisms underlying carotenoid metabolism in diatoms and proposing T. rotula as a potential candidate for fucoxanthin production.