Vladan Ondřej

This study identified the causative agent of powdery mildew on Azadirachta indica (Sapindales, Meliaceae) in the Dominican Republic, using molecular phylogenetic analysis of internal transcribed spacer (ITS) and large subunit (LSU) sequences of rDNA, and morphological examinations. The infection was caused by Erysiphe necator, a pathogen primarily associated with Vitis spp. Together with other recent reports of E. necator on different host plants in Brazil, the host range of this pathogen has been expanded in tropical regions of Central America and the Caribbean region.

The level of phytohormones such as abscisic acid (ABA) and auxins (Aux) changes dynamically during embryogenesis. Knowledge of the transcriptional activity of the genes of their metabolic pathways is essential for a deeper understanding of embryogenesis itself; however, it could also help breeding programs of important plants, such as Cannabis sativa, attractive for the pharmaceutical, textile, cosmetic, and food industries. This work aimed to find out how genes of metabolic pathways of Aux (IAA-1, IAA-2, X15-1, X15-2) and ABA (PP2C-1) alongside one member of the LEA gene family (CanLea34) are expressed in embryos depending on the developmental stage and the embryo cultivation in vitro. Walking stick (WS) and mature (M) cultivated and uncultivated embryos of C. sativa cultivars ‘KC Dora’ and ‘USO 31’ were analyzed. The RT-qPCR results indicated that for the development of immature (VH) embryos, the genes (IAA-1, IAA-2) are likely to be fundamental. Only an increased expression of the CanLea34 gene was characteristic of the fully maturated (M) embryos. In addition, this feature was significantly increased by cultivation. In conclusion, the cultivation led to the upsurge of expression of all studied genes.

Polyploidization in plants, which involves doubling or further multiplying of genome, has the potential to improve the constituents that make medicinal plants, like Ajuga reptans, attractive to the pharmaceutical, cosmetics, and food production industries; botanical pesticide effects could also be derived. The aim of this study was to determine how artificial polyploidization in A. reptans plants affected the composition and quantity of biologically active substances from the glycoside and phytoecdysone families. Diploids and artificial tetraploids of A. reptans were analyzed. Changes in the contents of trans-teupolioside, trans-verbascoside, and 20-hydroxyecdysone were evident in the aboveground parts of the cultivated plants (e.g., leaves and flowers). The tetraploid lines of Ajuga plants displayed variability in, and increased levels of, trans-teupolioside and trans-verbascoside content. The 20-hydroxecdysone content was slightly higher in tetraploids. These findings indicated that Ajuga tetraploids could be used in breeding programs to enhance the yield of substances with potential medicinal and industrial applications.

Professor Aleš Lebeda at Seventy | Vladan Ondřej, Ian R. Curte, Geoffrey R. Dixon, Jeremy J. Burdon, Ray D. Martyn, Larry D. Knerr, Ir. Kees Reinink | Agricultural Journals

The aim of this work was to find an effective protocol for in vitro propagation and to perform the in vitro polyploidization of diploid Thymus vulgaris (2n = 30) using two experimental methods based on the use of oryzalin, an antimitotic agent. The ploidy level of the obtained shoots was checked by flow cytometric analysis. The most efficient conditions for inducing polyploidy were oryzalin concentrations of 0.346 and 1.73 mg L⁻¹ present in the medium for two weeks. The vital polyploid shoots were multiplied for further evaluation, rooting and final transfer to nonsterile glasshouse and field conditions. The chemical compositions of the essential oils (EOs)—which were obtained from dried field grown plants by steam distillation—were analyzed by gas chromatography/mass spectrometry (GC/MS). The identified substances contributed approximately 95% to the total peak area. Statistical analysis revealed that the tetraploid subclone and the diploid reference plant do not differ in total terpene content, but they do differ in the relative proportions of all the individual terpenes with the exception of α-pinene and UN5, indicating that both clones produce EOs of different quality. The obtained results showed the possibility of developing more efficient botanical insecticides based on EOs obtained from the tetraploid plants.

The aim and novelty of this paper are found in assessing the influence of inhibitors and antibiotics on intact cell MALDI-TOF mass spectra of the cyanobacterium Synechococcus sp. UPOC S4 and to check the impact on reliability of identification. Defining the limits of this method is important for its use in biology and applied science. The compounds included inhibitors of respiration, glycolysis, citrate cycle, and proteosynthesis. They were used at 1–10 μM concentrations and different periods of up to 3 weeks. Cells were also grown without inhibitors in a microgravity because of expected strong effects. Mass spectra were evaluated using controls and interpreted in terms of differential peaks and their assignment to protein sequences by mass. Antibiotics, azide, and bromopyruvate had the greatest impact. The spectral patterns were markedly altered after a prolonged incubation at higher concentrations, which precluded identification in the database of reference spectra. The incubation in microgravity showed a similar effect. These differences were evident in dendrograms constructed from the spectral data. Enzyme inhibitors affected the spectra to a smaller extent. This study shows that only a long-term presence of antibiotics and strong metabolic inhibitors in the medium at 10⁻⁵ M concentrations hinders the correct identification of cyanobacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF).

The aim of the research was to establish an efficient procedure for in vitro micropropagation in order to obtain numbers of identical plants for in vitro polyploidization of Humulus lupulus (2n = 20), using antimicrotubule agent oryzalin. For this purpose, the polyploidization was carried out for H. lupulus Osvald’s clones 31, 74, 114, and for ‘Sladek’ cultivar. The two experimental methods – the cultivation of nodal segments on medium with different concentrations of oryzalin (1, 5, and 10 µM) for 2 weeks and the irrigation of nodal segments with oryzalin (10 and 20 µM) for 24 and 48 h were chosen for inducing for polyploid plantlets of H. lupulus. This procedure provided tetraploids, which were identified by flow cytometry using internal standardization method and confirmed using chromosome counting of methaphasic cells from the root tips and morphological observations. The influence of chromosome doubling was also verified with stomata characterization. The polyploid plants were propagated for next evaluation, rooting and transfer to nonsterile conditions and into field. After chromosome doubling, using some different concentration of oryzalin, some plantlets became tetraploids, no mixoploids were detected. The highest efficiency of polyploidization was achieved for clone 72 after 2-week treatment of oryzalin supplemented medium. On the other hand, for method based on the irrigation of nodal segments with oryzalin, the most efficient conditions were treatment with 10 µM and 20 µM oryzalin for 24 and 48 h, respectively.

Gravitational force is one of environmental factors that influence growth and development of plants. Changes in this force, including microgravity, can be one of the stress factor which plants have to adapt to cope with. That kind of stress can lead to several abnormalities such as chromosomal breakage, morphological abnormalities or changes in gene expression. The aim of this study was to examine the influence of simulated microgravity on gene expression of Arabidopsis thaliana embryos by use Random Positioning Machine (RPM). RPM is laboratory facility that can generate conditions comparable to the true microgravity. This paper studies effect of simulated microgravity on expression of genes which are involved in plant embryogenesis ( LEAFY COTYLEDON, LATE EMBRYOGENESIS ABUNDANT ), antioxidative system ( CATALASE ), mechanical stimuli ( TOUCH ) and gravitropism ( SCARECROW, SHOOT GRAVITROPISM2 ). Changes in gene expression were detected using quantitative real-time PCR (qRT-PCR). Several of tested genes had increased transcript levels after the influence of simulated microgravity. Specifically, catalase ( CAT3 ), LECs ( LEC1 ), touch ( TCH2/CML24 ), and gravitropism ( SGR2 ) genes achieved significantly increased relative expression (level ≥ 2). The changes in the levels of expression on embryos of Arabidopsis depend on the type of genes and principally on the timing of the influence of the simulated microgravity.