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Urea is intensively utilized as a nitrogen fertilizer in agriculture, originating either from root uptake or from catabolism of arginine by arginase. Despite its extensive use, the underlying physiological mechanisms of urea, particularly its adverse effects on seed germination and seedling growth under salt stress, remain unclear. In this study, we demonstrate that salt stress induces excessive hydrolysis of arginine-derived urea, leading to an increase in cytoplasmic pH within seed radical cells, which, in turn, triggers salt-induced inhibition of seed germination (SISG) and hampers seedling growth. Our findings challenge the long-held belief that ammonium accumulation and toxicity are the primary causes of SISG, offering a novel perspective on the mechanism underlying these processes. This study provides significant insights into the physiological impact of urea hydrolysis under salt stress, contributing to a better understanding of SISG. [ABSTRACT FROM AUTHOR]

The results of assessing the primary dormancy, greatly important for adaptation, of seeds of A. thaliana plants from northern natural populations are presented. The temperature history of the maternal plant during the period of seed maturation was found to control the germination of seed progeny. The dependence of the transcriptional activity of the FT gene in plant pods on temperature history of the maternal plant was identified: the activity was found to be higher at a colder temperature (16°C) compared to warmer conditions. For DOG1, a similar relationship is true only for some populations that include both late-flowering and relatively early-flowering plants. This is likely due to the fact that the latest ecotypes of A.thaliana have special regulatory mechanisms of the physiological functions of DOG1. It was shown that, in a cold climate, seeds of the majority of A. thaliana plants experience deeper dormancy at a high temperature (22°C), which ensures their germination in autumn and flowering in spring, after the end of vernalization. Nevertheless, a portion of seeds was found to be able to germinate at 22°C, possibly suggesting a mixture of alternative strategies of the life cycle of A. thaliana plants in the Karelian populations. In some populations, both winter and summer annuals are present, which creates an adaptive potential for the species to survive in a harsh and unstable environment in the northern periphery of the range of the species. [ABSTRACT FROM AUTHOR]

Microplastics have garnered global attention due to their potential ecological risks. Research shows micro/nano-plastics pollution has adverse effects on plant growth, development, and physiological characteristics. However, the mechanisms underlying these effects remain unclear. The study examined the effects of polystyrene micro/nano-plastics with varying sizes and concentrations on different physiological and biochemical markers of A. thaliana. The indicators assessed include seed viability, growth, chlorophyll content, accumulation of root reactive oxygen species, and root exudates. Using fluorescence labeling, we investigated the absorption and translocation processes of micro/nano-plastics in A. thaliana. We also performed transcriptomic analysis to better understand the particular mechanisms of micro/nano-plastics. It indicated that micro/nano-plastics had an adverse effect on seed germination, especially under high concentration and small particle size treatments. This effect diminished with prolonged exposure. High concentrations at 50 nm and 100 nm treatment groups significantly inhibited the growth. Conversely, low concentrations of 1000 nm had a promoting effect. Exposure to micro/nano-plastics potentially resulted in decreased chlorophyll content, the accumulation of H 2 O 2 in roots, and stimulated root secretion of oxalic acid. Through transcriptomic analysis, the gene expression linked to micro/nano-plastic treatments of varying sizes enriched multiple metabolic pathways, impacting plant growth, development, environmental adaptation, metabolism, pigment synthesis, and stress response. [Display omitted] • Polystyrene micro/nanoplastics impact Arabidopsis thaliana physiology & biochemistry. • Low-concentration of 1000 nm polystyrene micro/nanoplastics promoted A. thaliana growth. • A. thaliana 's absorption & accumulation polystyrene micro/nanoplastics from 50–1000 nm. • Polystyrene micro/nanoplastics' size impacts gene expression in A. thaliana leaves & roots. [ABSTRACT FROM AUTHOR]