The Earth’s geomagnetic field (GMF, 25-65 µT) modulates plant physiology, but responses to magnetic deprivation remain poorly understood. We investigated how a near-null magnetic field (NNMF, ∼30 nT) impacts Mentha longifolia , focusing on the interplay between primary physiology, stress signalling, and specialized metabolism, particularly essential oil yield, carvone biosynthesis and phenolic compounds. NNMF altered photosynthetic performance, reducing chlorophyll a and carotenoid contents, PSII quantum yield under illumination, and rapidly reversible thermal energy dissipation. This photosynthetic energy deficit coincided with transcriptional repression of MEP pathway genes including IspG and GDPS , and was associated with reduced essential oil yield and lower accumulation of major monoterpenes, particularly carvone. The altered photosynthetic performance was accompanied by organ-specific ROS responses, including an approximately 80% increase in root H 2 O 2 and a reduction in root protein content, together with transcriptional downregulation of genes encoding antioxidant enzymes, including CAT and APX . Phytohormone profiling revealed organ-specific responses to NNMF, including opposite changes in OPDA and cytokinin-related metabolites between roots and shoots, together with reduced SA levels in both organs. Consequently, phenylpropanoid metabolism was altered, causing a ∼50% reduction in total phenolics and CHI downregulation, alongside structural flavonoid changes. Overall, GMF deprivation was associated with a stress response characterized by altered photosynthetic performance, organ-specific ROS dynamics, hormonal remodelling, and changes in specialized metabolism, resulting in reduced essential oil production and altered phenolic composition in M. longifolia .
Stomata regulate water loss and carbon assimilation in response to environmental changes such as soil water deficit and high air temperature. The effects of these environmental stresses on tree growth and ecophysiological parameters linked with photosynthesis and gas exchange, such as stomata, are mostly studied separately, even though they often occur concurrently in nature. Two Populus euramericana genotypes grown under controlled chamber were first subjected to soil water deficit at ambient air temperature and then to high temperature. We measured leaf gas exchange and stomatal conductance (gsw) dynamics in response to changes in irradiance or vapor pressure deficit. Physiological and morphological traits were assessed in relation to stomatal responses. At elevated temperature, stomata exhibited a two-step (bimodal) response, characterized by an initial decline in gsw followed by a recovery. The genotypes differed slightly in gsw dynamics in response to irradiance and VPD, particularly after a high-temperature event. Faster stomatal responses did not appear to be linked to stomatal morphology. Our results reveal a trade-off between water loss and carbon gain under combined stresses.
Tartary buckwheat has gained increasing popularity and demand worldwide in recent years. As a gluten-free grain, it contains complete proteins with a well-balanced profile of essential amino acids. It is also rich in beneficial phytochemicals, contributing to its significant health benefits. In this study, we characterized the zinc/iron-regulated transporter-like protein (ZIP) family in Tartary buckwheat. Expression of FtZIP12, as measured by RT-qPCR and a β-glucuronidase (GUS) reporter assay, is upregulated under zinc-deficient conditions. Functional complementation assays in yeast demonstrated that FtZIP12 enhances zinc uptake. This finding is further confirmed in transgenic hairy roots, where FtZIP12 expression leads to increased zinc accumulation. In addition, we found that the basic leucine zipper (bZIP) transcription factor FtbZIP61 is significantly induced by Zn deficiency. Further investigation revealed that FtbZIP61, along with its homologs FtbZIP47 and FtbZIP79, binds to the FtZIP12 promoter and activates its transcription. Our findings represent a significant step forward in unraveling the molecular mechanism of zinc accumulation in Tartary buckwheat, paving the way for improving zinc biofortification to alleviate human zinc deficiency.
The Earth’s geomagnetic field (GMF, 25-65 µT) modulates plant physiology, but responses to magnetic deprivation remain poorly understood. We investigated how a near-null magnetic field (NNMF, ∼30 nT) impacts Mentha longifolia, focusing on the interplay between primary physiology, stress signalling, and specialized metabolism, particularly essential oil yield, carvone biosynthesis and phenolic compounds. NNMF altered photosynthetic performance, reducing chlorophyll a and carotenoid contents, PSII quantum yield under illumination, and rapidly reversible thermal energy dissipation. This photosynthetic energy deficit coincided with transcriptional repression of MEP pathway genes including IspG and GDPS, and was associated with reduced essential oil yield and lower accumulation of major monoterpenes, particularly carvone. The altered photosynthetic performance was accompanied by organ-specific ROS responses, including an approximately 80% increase in root H2O2 and a reduction in root protein content, together with transcriptional downregulation of genes encoding antioxidant enzymes, including CAT and APX. Phytohormone profiling revealed organ-specific responses to NNMF, including opposite changes in OPDA and cytokinin-related metabolites between roots and shoots, together with reduced SA levels in both organs. Consequently, phenylpropanoid metabolism was altered, causing a ∼50% reduction in total phenolics and CHI downregulation, alongside structural flavonoid changes. Overall, GMF deprivation was associated with a stress response characterized by altered photosynthetic performance, organ-specific ROS dynamics, hormonal remodelling, and changes in specialized metabolism, resulting in reduced essential oil production and altered phenolic composition in M. longifolia.
