Search

During their evolution, plants have developed a number of mechanisms to resist biotic and abiotic stressors. Evolution is an endless process, which continues, of course, even today. In the case of crop plants, however, evolution's original contingency is replaced by targeted breeding. This is based on the same natural processes - mutagenesis, hybridization and selection. However, the classical techniques are now significantly complemented by genetic engineering methods. Based on knowledge of the molecular basis of plant stress resistance mechanisms, these processes are subsequently used to obtain new, practically- useful genotypes. The present paper is therefore aimed at explaining the biological effects of drought or salinity from the molecular level to the complex reactions of the whole organism. Subsequently, the paper illustrates various opportunities for using transgenic techniques (gene modifications, GM) for the construction of crops resistant to these stressors, explains their gene background and illustrates, in selected examples, both the history of partial research strategies, their present status and also their prospects. In addition, the paper briefly informs about a new technique of gene editing (GE) based on the mechanisms of natural repair of the plants' own genes. This precise mutagenesis has also found practical, revolutionary, applications both in human gene therapy and in effective "nature-close" breeding and plant protection. [ABSTRACT FROM AUTHOR]

Global climate change is an important and topical issue that the public, and especially the younger generation, should be well acquainted with. However, relatively little attention is paid to this issue in the currently valid biology textbooks and in the Framework Educational Programme (FEP) for Czech grammar schools. It is not beneficial to pass on knowledge about this issue to students only in the form of bare facts that would have to be memorized. On the contrary, it is desirable that pupils themselves actively acquire information on the issue, think about it critically and understand it. Therefore, the aim of this paper is to follow up on the article "Water and Plant Stress" published in issue number 4/2019 of this journal in order to elaborate the given topic in a didactic manner, in the form of nineteen active learning tasks intended primarily for pupils at upper secondary schools. Pupils have to draw upon information from introductory texts, graphs, tables or pictures to solve them correctly and critically think about them and to some extent can apply previously acquired knowledge and experience. Such acquired knowledge can then be applied more convincingly not only at school but also outside of it. The author's solutions are attached to the tasks. The proposed tasks were selected from a set of 30 tasks elaborated on the given topic, which were tentatively tested during pedagogical practice at a grammar school. [ABSTRACT FROM AUTHOR]

In plants, different forms of programmed cell death (PCD) have been identified, but they only partially correspond to those described for animals, which is most probably due to structural differences between animal and plant cells. Here, the results show that in tobacco BY-2 cells, bleomycin (BLM), an inducer of double-strand breaks (DSBs), triggers a novel type of non-apoptotic PCD with paraptotic-like features. Analysis of numerous PCD markers revealed an extensive vacuolization, vacuolar rupture, and chromatin condensation, but no apoptotic DNA fragmentation, fragmentation of the nuclei, or sensitivity to caspase inhibitors. BLM-induced PCD was cell cycle regulated, occurring predominantly upon G2/M cell cycle checkpoint activation. In addition, this paraptotic-like PCD was at least partially inhibited by caffeine, a known inhibitor of DNA damage sensor kinases ATM and ATR. Interestingly, overexpression of one NtE2F transcriptional factor, whose homologues play a dual role in animal apoptosis and DNA repair, reduced PCD induction and modulated G2/M checkpoint activation in BY-2 cells. These observations provide a solid ground for further investigations into the paraptotic-like PCD in plants, which might represent an ancestral non-apoptotic form of PCD conserved among animals, protists, and plants. [ABSTRACT FROM PUBLISHER]

The co-ordination of cell wall synthesis with plant cell expansion is an important topic of contemporary plant biology research. In studies of cell wall synthesis pathways, cellulose synthesis inhibitors are broadly used. It is demonstrated here that ancymidol, known as a plant growth retardant primarily affecting gibberellin biosynthesis, is also capable of inhibiting cellulose synthesis. Its ability to inhibit cellulose synthesis is not related to its anti-gibberellin action and possesses some unique features never previously observed when conventional cellulose synthesis inhibitors were used. It is suggested that ancymidol targets the cell wall synthesis pathway at a regulatory step where cell wall synthesis and cell expansion are coupled. The elucidation of the ancymidol target in plant cells could potentially contribute to our understanding of cell wall synthesis and cell expansion control. [ABSTRACT FROM PUBLISHER]

Changes in cell viability, proliferation, cell and nuclear morphology including nuclear and DNA fragmentation induced by 0.05 and 1 mM CdSO4 (Cd2+) in tobacco BY-2 cell line (Nicotiana tabacum L.) were studied in the course of 7 days. Simultaneously changes in endogenous contents of both free and conjugated forms of polyamines (PAs) were investigated for 3 days. The application of 0.05 mM Cd2+ evoked decline of cell viability to approximately 60% during the first 24 h of treatment. Later on degradation of cytoplasmic strands, formation of the stress granules and vesicles, modifications in size and shape of the nuclei, including their fragmentation, were observed in the surviving cells. Their proliferation was blocked and cells elongated. Beginning the first day of treatment TUNEL-positive nuclei were detected in cells cultivated in medium containing 0.05 mM Cd2+. Treatment with highly toxic 1 mM Cd2+ induced fast decrease of cell viability (no viable cells remained after 6-h treatment) and cell death occurred before DNA cleavage might be initiated. The exposure of tobacco BY-2 cells to 0.05 mM Cd2+ resulted in a marked accumulation of total PAs (represented by the sum of free PAs and their perchloric acid (PCA)-soluble and PCA-insoluble conjugates) during 3-day treatment. The increase in total PA contents was primarily caused by the increase in putrescine (Put) concentration. The accumulation of free spermidine (Spd) and spermine (Spm) at 12 and 24 h in 0.05 mM Cd2+ treated BY-2 cells and high contents of Spd and especially Spm determined in dead cells after 1 mM Cd2+ application was observed. The participation of PA conjugation with hydroxycinnamic acids and PA oxidative deamination in maintaining of free PA levels in BY-2 cells under Cd2+-induced oxidative stress is discussed. [Copyright &y& Elsevier]