In the face of climate change, progressive degradation of the environment, including agricultural land negatively affecting plant growth and development, endangers plant productivity. Seeking efficient and sustainable agricultural techniques to replace agricultural chemicals is one of the most important challenges nowadays. The use of plant growth-promoting microorganisms is among the most promising approaches; however, molecular mechanisms underneath plant–microbe interactions are still poorly understood. In this review, we summarized the knowledge on plant–microbe interactions, highlighting the role of microbial and plant proteins and metabolites in the formation of symbiotic relationships. This review covers rhizosphere and phyllosphere microbiomes, the role of root exudates in plant–microorganism interactions, the functioning of the plant’s immune system during the plant–microorganism interactions. We also emphasized the possible role of the stringent response and the evolutionarily conserved mechanism during the established interaction between plants and microorganisms. As a case study, we discussed fungi belonging to the genus Trichoderma. Our review aims to summarize the existing knowledge about plant–microorganism interactions and to highlight molecular pathways that need further investigation.

In this work, we present the results of the inoculation of canola seeds (Brassica napus L.) with Trichoderma viride strains that promote the growth of plants. Seven morphologically different strains of T. viride (TvI-VII) were shown to be capable of synthesizing auxins and exhibited cellulolytic and pectinolytic activities. To gain a deeper insight into the molecular mechanisms underlying canola–T. viride interactions, we analyzed the canola stress genes metallothioneins (BnMT1-3) and stringent response genes (BnRSH1-3 and BnCRSH). We demonstrated the presence of cis-regulatory elements responsive to fungal elicitors in the promoter regions of B. napus MT and RSH genes and observed changes in the levels of the transcripts of the above-mentioned genes in response to root colonization by the tested fungal strains. Of the seven tested strains, under laboratory conditions, T. viride VII stimulated the formation of roots and the growth of canola seedlings to the greatest extent. An experiment conducted under field conditions during drought showed that the inoculation of canola seeds with a suspension of T. viride VII spores increased yield by 16.7%. There was also a positive effect of the fungus on the height and branching of the plants, the number of siliques, and the mass of a thousand seeds. We suggest that the T. viride strain TvVII can be used in modern sustainable agriculture as a bioinoculant and seed coating to protect B. napus from drought.

Metallothioneins (MTs) are a family of small proteins rich in cysteine residues. The sulfhydryl group of metallothioneins can bind to metal ions, maintaining metal homeostasis and protecting the cells from damage caused by toxic heavy metals. Moreover, MTs can function as reactive oxygen species scavengers since cysteine thiols undergo reversible and irreversible oxidation. Here, we identified 21 metallothionein genes (AsMTs) in the oat (Avena sativa L.) genome, which were divided into four types depending on the amino acid sequences of putative proteins encoded by identified genes. Analysis of promoter sequences showed that MTs might respond to a variety of stimuli, including biotic and abiotic stresses and phytohormones. The results of qRT-PCR showed that all four types of AsMTs are differentially expressed during the first 48 hours of seed germination. Moreover, stress induced by the application of zinc, cadmium, and a mixture of zinc and cadmium affects the expression of oat MTs variously depending on the MT type, indicating that AsMT1-4 fulfil different roles in plant cells.

Novel carboxymethylcellulose (CMC) films with liquid products of pyrolysis (LPP) from wood pine were produced. The obtained CMC-LPP films were plasticized with 5% glycerol. CMC-LPP films were a light brown colour with a characteristic smoky scent, and showed a higher oxygen permeability when compared to control film without the addition of the LPP. CMC-LPP exhibited high antioxidant activity (5 and 18 times higher than CMC films). Furthermore, the antibacterial activity of the CMC-LPP films was tested, showing a strong inhibiting growth effect on the seven tested human pathogenic bacteria. The new material had the most substantial bacteriostatic effect on Listeria monocytogenes, Salmonella typhimurium, and Pseudomonas aeruginosa. Introduction of LPP to plasticised CMC produces an eco-friendly material with biocidal effect and favourable mechanical and structural properties, which shows its potential for possible use in many industries.

Progressive climate change increases drought frequency, severely impacting crop growth and yield. New eco-friendly alternatives to chemical protection agents and fertilisers are needed to reduce pollution and enhance plant health. This study evaluated the effects of the plant growth-promoting rhizobacteria (PGPR) and the hydrogel (potassium polyacrylate) on Brassica napus L. during drought conditions. After in vitro and pot experiments, Serratia plymuthica was selected from six PGPR candidates based on its ability to enhance plant biomass, shoot length, and number of internodes. The seed viability test, reactive oxygen species accumulation, and SOD activity showed no adverse effects of applying hydrogel to canola seeds. Moreover, the hydrogel did not show toxicity towards tested bacterial strains. Field trials during the drought demonstrated that inoculation with S. plymuthica significantly increased the number of siliques (16.48%) and yield (19.93%), compared to controls. Plants grown from inoculated seeds were also taller (3.28%) and had more branches (39.99%). We also analysed seedling emergence, number of internodes, thousand seeds’ weight, and seed moisture. The hydrogel applied to the soil delayed seedling emergence and dampened the growth-promoting effect of S. plymuthica, resulting in reduced yield. Compared with plants inoculated with S. plymuthica, there was a decrease in the yield of plants treated solely with hydrogel and in plants treated with hydrogel and the bacterium of 23.61% and 27.79%, respectively. Our results indicate that S. plymuthica has a high potential for use in commercial canola farming, especially as an ingredient added to seed coatings.

Recent studies have shown that wood tar exhibits excellent potential as an additive to polymers for food packaging. In this study, we demonstrated that the differential temperature of dry pyrolysis of wood affects the antioxidant and antibacterial activities of the liquid pyrolysis products (LPP). Birch LPP showed, on average, approximately 16% higher reducing power in the ferric-reducing antioxidant power (FRAP) assay and, on average, approximately 29% lower free radical scavenging activity than pine LPP. Thermal characterization suggests a qualitatively similar chemical composition among the tested fractions, with the 500 °C pyrolysis fraction showing the highest thermal resistance (lowest mass loss). Thermal characterization indicated similarities in the qualitative chemical composition of the tested fractions. Analyzed products demonstrated bactericidal activity against human- or plant-pathogenic bacteria and exhibited poor antimicrobial activity towards probiotic bacteria. Specifically, Lactoplantibacillus sp. and L. rhamnosus were, on average, approximately 61% and 45% less affected, respectively, compared to the most sensitive E. coli. We demonstrate apparent, predominantly substrate-driven differences in antibacterial activity, with Gram-negative bacteria being more susceptible to pine products and Gram-positive bacteria being more susceptible to birch products.