The latest research has shown that chitosan acts as a growth stimulator and elicitor in plants, including resistance to biotic and abiotic factors. However, increasing concentrations could possibly make chitosan a source of stress for plants. In this study, we investigated the effect of low-molecular-weight chitosan hydrolysate on the root development of tomato (Solanum lycoperscum) cultivars Red Cherry, Lel, and Tytan. The growth rate change, together with total phenolic content, phenylalanine ammonia-lyase (PAL) activity, and gene expression, were studied in relation to tomatoes. High concentrations of chitosan negatively affect the growth of tomato seedlings and contribute to changes in the tropism of the seedling roots. After the addition of chitosan hydrolysate, the PAL activity and the total phenolic content decreased 24 h later. PAL is a key enzyme in the biosynthesis of many plant stress factors. An analysis of the tomato PAL gene family was carried out. The SlPAL gene expression in the seedlings of cv. Cherry increased 1.5 times after 48 h, while in cv. Lel, the expression stably decreased in the presence of chitosan. The obtained results are supposed to aid our understanding of the mechanisms underlying the effects of chitosan on plant development and further its successful application in agriculture as well as in research on plant stress.

In recent decades, heavy metal pollution has become a significant environmental stress factor. Plants are characterized by high biochemical plasticity and can adjust their metabolism to ensure survival under a changing environment. Here we report, to our knowledge, the first gas chromatography-mass spectrometry (GC-MS)-based metabolomics study of Zn-induced stress responses in Amaranthus caudatus plants. The study was performed with root and leaf aqueous methanolic extracts after their lyophilization and sequential derivatization with methoxylamine hydrochloride and N-methyl-N-(trimethylsilyl)trifluoroacetamide. In total, 419 derivatives were detected in the samples, and 144 of them could be putatively annotated. The metabolic shifts in seven-week-old A. caudatus plants in response to a seven-day treatment with 300 µmol/L ZnSO₄·7H₂O in nutrient solution were organ-specific and more pronounced in roots. Most of the responsive metabolites were up-regulated and dominated by sugars and sugar acids. The revealed effects could be attributed to the involvement of these metabolites in osmotic regulation, antioxidant protection and Zn²⁺ complexation. A 59-fold up-regulation of gluconic acid in roots distinctly indicated enhanced glucose oxidation due to oxidative stress upon the Zn treatment. Gluconic acid might be further employed in Zn²⁺ complexation. Pronounced Zn-induced up-regulation of salicylic acid in roots and shoots suggested a key role of this hormone in stress signaling and activation of Zn stress tolerance mechanisms. Overall, our study provides the first insight into the general trends of Zn-induced biochemical rearrangements and main adaptive metabolic shifts in A. caudatus.

Soil microorganisms play a vital role in increasing the availability of phosphorus (P) for plants through mineralization of organic P and solubilization of precipitated P compounds. In this two-year study, we analyzed several P-solubilizing microorganisms (PSMs) of the genus Bacillus and their consortiums for the ability to release soluble P from apatite concentrates of various grinding degrees using ryegrass (Lolium multiflorum Lam.) as a model plant. The effects were accessed by analyzing plant growth and nutrient assimilation. The greatest effect on root system development and plant biomass accumulation (dry weight) was observed for the apatite concentrate of standard grinding in combination with Bacillus megaterium BI14 and Bacillus subtilis BI2 and Bacillus velezensis BS89 strains. Although the introduction of apatite concentrates led to an increase in the content of total strontium in soil, the levels of strontium did not exceed the maximum allowable concentration, and the accumulation of mobile strontium by plants was unchanged; importantly, the use of tested PSMs led to a decrease in the strontium content in the green biomass of ryegrass. Our results indicate that biologized apatite concentrates in combination with PSMs represent promising fertilizers that can provide a source of soluble P to be readily assimilated by plants.

In addition to leaves, photosynthesis can occur in other green plant organs, including developing seeds of many crops. While the majority of studies examining photosynthesis are concentrated on the leaf level, the role of other green tissues in the production of total photoassimilates has been largely overlooked. The present work studies the photosynthetic behavior of leaves and non-foliar (pericarps, coats, and cotyledons) organs of pea (Pisum sativum L.) plants at the middle stage of seed maturation. The Chl a fluorescence transient was examined based on OJIP kinetics using the FluorPen FP 110. A discrepancy was observed between the performance index (PI_ABS) for foliar and non-foliar plant tissues, with the highest level noted in the leaves. The number of absorbed photons (ABS) and captured energy flow (TRo) per reaction center (RC) were elevated in the non-foliar tissues, which resulted in a faster reduction in Q_A. Conversely, the energy dissipation flux per RC (DIo/RC and PHI_Do) indicated an increase in the overall dissipation potential of active reaction centers of photosystem II. This phenomenon was attributed to the presence of a higher number of inactive RCs in tissues that had developed under low light intensity. Furthermore, the expression of genes associated with proteins and enzymes that regulate ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) activity was observed, including chaperonins Cpn60α and Cpn60β, RuBisCO activase, as well as phosphoribulokinase. The expression of these genes was found to differ between foliar and non-foliar tissues, indicating that the activation state of RuBisCO may be modified in response to light intensity. Overall, the present study provides insights into the mechanisms by which non-foliar green tissues of plants adapt to efficient light capture and utilization under low light conditions.

Phytoremediation of oil pollution using free-floating aquatic plants is a promising method for water body cleaning. In this study, the influence of Eichhornia crassipes and Pistia stratiotes on the degradation of oil pollution was investigated. The loss of oil alkanes and the rheological characteristics of water were evaluated, and an analysis of the emerging rhizospheric microbial communities was carried out using high-throughput sequencing. The presence of E. crassipes and P. stratiotes plants in oil-contaminated tanks had no effect on the degradation of oil alkanes. However, the presence of plants promoted the development of rhizospheric bacteria capable of growing in oil-contaminated environments. Alpha diversity of microbial communities in oil-contaminated samples was higher in the presence of plants. Additionally, plants significantly reduced the water/oil interfacial tension, which facilitated the availability of hydrocarbons for biodegradation. A difference was noted in the microbiome between E. crassipes and P. stratiotes. Changes in the composition of microbial communities highlight the potential of E. crassipes and P. stratiotes as rhizospheric hosts for microorganisms in the phytoremediation of water bodies.

Biolistics is one of the widely used methods to deliver nucleic acids into plant cells. In this work, we optimized the protocol for biolistic transformation of Nicotiana tabacum with the gene gun PDS-1000/He Biolistic Particle Delivery System. The Green Fluorescent Protein (GFP) gene was used as a marker. The optimal parameters for the transformation of N. tabacum leaf cells were determined as: pressure, 1350 psi; tungsten particle size, 1.3 μm; plasmid DNA purification method, ethanol re-precipitation. The results should be useful for the development of biolistic transformation protocols for plant cells, including application for plant genome editing of agricultural species.