Response of Three Miscanthus × giganteus Cultivars to Toxic Elements Stress: Part 1, Plant Defence Mechanisms

Miscanthus × giganteus demonstrated good phytostabilization potentials in toxic element (TE) contaminated soils. However, information about its tolerance to elevated concentrations is still scarce. Therefore, an ex-situ pot experiment was launched using three cultivars (termed B, U, and A) grown in soils with a gradient Cd, Pb and Zn concentrations. Control plants were also cultivated in non-contaminated soil. Results show that the number of tillers per plant, stem diameter as well as leaf photosynthetic pigments (chlorophyll a, b and carotenoids) were negatively impacted by soil contamination. On the other hand, phenolic compounds, flavonoids, tannins, and anthocyanins levels along with the antioxidant enzymatic activities of superoxide dismutase, ascorbate peroxidase and glutathione reductase increased in the plants grown on contaminated soils. Altogether, these data demonstrate that miscanthus is impacted by concentrations of toxic elements yet is able to tolerate high levels of soil contamination. These results may contribute to clarifying the miscanthus tolerance strategy against high contamination levels and its efficiency in phytoremediation.

Bać się czy się nie bać? Bioakumulacja, bioindykacja i toksyczność metali ciężkich Rośliny w świetle badań terenowych i laboratoryjnych

Heavy metals that pose a threat to the environment include lead (Pb), zinc (Zn), copper (Cu), arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni) and mercury (Hg). Biomonitoring of environmental quality using plants is widely accepted as a reliable and inexpensive way of obtaining information on contamination also by heavy metals. It allows the assessment of the direction of changes in the natural environment and development of prognoses and methods for early warning related to predicted transformations in ecosystems. This paper presents the results of field and laboratory studies on floristic biodiversity in the areas of southern Poland related to extraction and processing of Zn and Pb ores. The paper also shows the selected plant defence mechanisms against the excess of heavy metals and the results of bioindication studies using different plant species, including the selected metallophytes related to the assessment of contamination levels and the most frequently used plant ecophysiological parameters. It is necessary to monitor contamination level, popularize knowledge and take action at the level of local authorities to mitigate adverse effects of human activity, bearing in mind possible bioaccumulation of heavy metals in the food chain and the adverse health effects associated with environmental contamination.

Possibilities of using yeast in biological plant protection

The metabolic activity of yeasts, as well as their common occurrence in the environment make them a potential source of compounds that can be used in biological plant protection. The article presents health-promoting effects of yeast on plants. The pro-health effect of yeast is related to the ability to provide plants with dissolved nutrients. Yeasts can also indirectly activate plant defence mechanisms and improve plant health status. The bioremediation properties and antagonism of yeasts against numerous economically important phytopathogens play an important role here. The research is also indicated that yeasts (Pichia membranifaciens, Pichia fermentans and Meyrozyma guilliermondii) in vitro show an antagonistic activity against their phytopathogens (Alternaria alternata, Rhizoctonia solani and Colletotrichum coccodes). All the mentioned aspects of yeast activity can be useful in creating high-quality biofertilizers and biopesticides.

Plant Defence Mechanisms Are Modulated by the Circadian System

Plant health is an important aspect of food security, with pathogens, pests, and herbivores all contributing to yield losses in crops. Plants’ defence against pathogens is complex and utilises several metabolic processes, including the circadian system, to coordinate their response. In this review, we examine how plants’ circadian rhythms contribute to defence mechanisms, particularly in response to bacterial pathogen attack. Circadian rhythms contribute to many aspects of the plant–pathogen interaction, although significant gaps in our understanding remain to be explored. We conclude that if these relationships are explored further, better disease management strategies could be revealed.

Chitosan primes plant defence mechanisms against Botrytis cinerea, including expression of Avr9/Cf-9 rapidly-elicited genes

Current crop protection strategies against the fungal pathogen Botrytis cinerea rely on a combination of conventional fungicides and host genetic resistance. However, due to pathogen evolution and legislation in the use of fungicides, these strategies are not sufficient to protect plants against this pathogen. Defence elicitors can stimulate plant defence mechanisms through a phenomenon known as priming. Priming results in a faster and/or stronger expression of resistance upon pathogen recognition by the host. This work aims to study priming of a commercial formulation of the elicitor chitosan. Treatments with chitosan result in induced resistance in solanaceous and brassicaceous plants. In tomato plants, enhanced resistance has been linked with priming of callose deposition and accumulation of the plant hormone jasmonic acid (JA). Large-scale transcriptomic analysis revealed that chitosan primes gene expression at early time-points after infection. In addition, two novel tomato genes with a characteristic priming profile were identified, Avr9/Cf-9 rapidly-elicited protein 75 (ACRE75) and 180 (ACRE180). Transient and stable overexpression of ACRE75, ACRE180 and their Nicotiana benthamiana homologs, revealed that they are positive regulators of plant resistance against B. cinerea. This provides valuable information in the search for strategies to protect Solanaceae plants against B. cinerea.