Pál Vági

Improvement of isolated microspore culture of pepper ( Capsicum annuum L.) via co-culture with ovary tissues of pepper or wheat

The influence of the developmental stage of microspores on establishing isolated microspore cultures of three Hungarian (‘Szegedi 80’, ‘Szegedi 178’, and ‘Remény’) and three Spanish (‘Jeromin’, ‘Jariza’, and ‘Jaranda’) pepper genotypes was investigated. Donor anthers containing 80% uninucleated and 20% binucleated microspores yielded the highest frequency of successful microspore cultures. Co-cultures with wheat, line ‘CY-45’, ovaries exhibited enhanced frequency of embryoid production than those with pepper ovaries. Differences in efficiency of isolated pepper microspore culture establishment were observed among different pepper genotypes. Green plantlets were regenerated from microspore-derived embryoids, but some were exhibited abnormal growth habits, such as leaf rosetting. A total of seven fertile microspore-derived plants were obtained, including three ‘Jariza’, three ‘Jaranda’, and a single ‘Szegedi 80’ plant.

Host range expansion in a powdery mildew fungus (Golovinomyces sp.) infecting Arabidopsis thaliana: Torenia fournieri as a new host

Since 2003, Torenia fournieri plants grown for experimental purposes were repeatedly infected by powdery mildew in a laboratory in Hungary. Based on morphological characteristics, the pathogen belonged to the mitosporic genus Oidium subgen. Reticuloidium, the anamorph stage of Golovinomyces. The rDNA ITS sequence was identical to that of two other powdery mildew fungi, infecting Arabidopsis and Veronica, respectively, in different parts of the world. According to a previous phylogenetic analysis of ITS and 28S rDNA sequences, those two powdery mildews belong to a recently evolved group of Golovinomyces characterized by multiple host range expansions during their evolution. Both the ITS sequence and the morphological data indicate that the powdery mildew anamorph infecting Torenia also belongs to this group. It is likely that the powdery mildew infections of the experimental T. fournieri plants, native to south-east Asia, were the result of a very recent host range expansion of a polyphagous Golovinomyces because (i) T. fournieri is absent from our region, except as an experimental plant grown in the laboratory, (ii) the powdery mildew fungus infecting this exotic plant belongs to a group of Golovinomyces where host range expansion is a frequent evolutionary scenario, (iii) cross-inoculation tests showed that this pathogen is also able to infect other plant species, notably A. thaliana and tobacco, and (iv) no Golovinomyces species are known to infect T. fournieri anywhere in the world. Although host range expansion has often been proposed as a common evolutionary process in the Erysiphales, and also in other biotrophic plant pathogens, this has not been clearly demonstrated in any case studies so far. To our knowledge, this is the first convincing case of a host range expansion event in the Erysiphales.

Terfezia disappears from the American truffle mycota as two new genera and Mattirolomyces species emerge

Reexamination and molecular phylogenetic analyses of American Terfezia species and Mattirolomyces tiffanyae revealed that their generic assignments were wrong. Therefore we here propose these combinations: Mattirolomyces spinosus comb. nov. (≡ Terfezia spinosa), Stouffera longii gen. & comb. nov. (≡ Terfezia longii) and Temperantia tiffanyae gen. & comb. nov. (≡ Mattirolomyces tiffanyae). In addition we describe a new species, Mattirolomyces mexicanus spec. nov. All species belong to the Pezizaceae. Based on these results Terfezia is not known from North America, Mattirolomyces is represented by two species and two new monotypic genera are present.

Simultaneous specific in planta visualization of root-colonizing fungi using fluorescence in situ hybridization (FISH)

In planta detection of mutualistic, endophytic, and pathogenic fungi commonly colonizing roots and other plant organs is not a routine task. We aimed to use fluorescence in situ hybridization (FISH) for simultaneous specific detection of different fungi colonizing the same tissue. We have adapted ribosomal RNA (rRNA) FISH for visualization of common mycorrhizal (arbuscular- and ectomycorrhiza) and endophytic fungi within roots of different plant species. Beside general probes, we designed and used specific ones hybridizing to the large subunit of rRNA with fluorescent dyes chosen to avoid or reduce the interference with the autofluorescence of plant tissues. We report here an optimized efficient protocol of rRNA FISH and the use of both epifluorescence and confocal laser scanning microscopy for simultaneous specific differential detection of those fungi colonizing the same root. The method could be applied for the characterization of other plant–fungal interactions, too. In planta FISH with specific probes labeled with appropriate fluorescent dyes could be used not only in basic research but to detect plant colonizing pathogenic fungi in their latent life-period.

Cd, Fe, and Light Sensitivity: Interrelationships in Cd-Treated Populus

Cadmium is a toxic heavy metal causing iron deficiency in the shoot and light sensitivity of photosynthetic tissues that leads to decreased photosynthetic performance and biomass production. Light intensity had strong impact on both photosynthetic activity and metal accumulation of cadmium-treated plants. At elevated irradiation, cadmium accumulation increased due to the higher dry mass of plants, but its allocation hardly changed. A considerable amount of iron accumulated in the roots, and iron concentration was higher in leaves developed at moderate rather than low irradiation. At the same time, the higher the irradiation the lower the maximal photochemical quantum efficiency. The decreased photochemical efficiency, however, started to recover after a week of Cd treatment at moderate light without substantial change in metal concentrations but following the accumulation of green fluorescent compounds. Both cadmium treatment and higher light caused the accumulation of flavonoids in leaf mesophyll vacuoles/chloroplasts, but accumulation of flavonols, fluorescing at 510 nm, was characteristic to cadmium stress. Therefore, flavonoids, which may act by scavenging reactive radicals, chelating Cd, and shielding against excess irradiation, play an important part in Cd stress tolerance of Populus, and may have special impact on its phytoremediation capacity.

Phosphorylation regulates the subcellular localization of Cucumber Mosaic Virus 2b protein

The 2b protein of Cucumber mosaic virus has a role in nearly all steps of the viral cycle including cell-to-cell movement, symptom induction and suppression of antiviral RNA silencing. Previous studies demonstrated the presence of 2b protein in the nucleus and in cytoplasm as well. Phosphorylation site of 2b protein is conserved in all CMV isolates, including proposed constitute motifs for casein kinase II and cyclin-dependent kinase 2. To discern the impact of 2b protein phosphorylation, we created eight different mutants to mimic the non-phosporylated (serine to alanine) as well as the phosphorylated state (serine to aspartic acid) of the protein. We compared these mutants to the wild-type (Rs-CMV) virus in terms of symptom induction, gene silencing suppressor activity as well as in cellular localization. Here, in this study we confirmed the phosphorylation of 2b protein in vivo, both in infected N. benthamiana and in infiltrated patches. Mutants containing aspartic acid in the phosphorylation site accumulated only in the cytoplasm indicating that phosphorylated 2b protein could not enter the nucleus. We identified a conserved dual phosphorylation switch in CMV 2b protein, which equilibrates the shuttling of the 2b protein between the nucleus and the cytoplasm, and regulates the suppressor activity of the 2b protein.

Development and isolation of the male gametophyte of Torenia fournieri

New methods were developed to isolate the male gametophyte of Torenia fournieri at any developmental stage. The stages were defined by light microscopic studies and identified by correlating morphological traits of the flower buds. Enzyme solutions were used to isolate gametophytic cells. Preliminary studies were carried out to determine the components of the cell wall, and the optimal osmotic pressures of the appropriate enzyme solutions were adjusted to the different developmental stages. We managed to isolate diploid microsporocytes, haploid microspores, cells of young and mature pollen grains, and sperm cells from growing pollen tubes. Isolated protoplasts were collected in microcapillaries to prepare them for further studies.

Identification of the Female-Produced Sex Pheromone of an Invasive Greenhouse Pest, the European Pepper Moth (Duponchelia fovealis)

The European pepper moth (Duponchelia fovealis, Lepidoptera, Crambidae, Spilomelinae) is an invasive pest of greenhouses in many countries, causing serious damages to horticultural plants. Coupled gas chromatographic-electroantennographic detection analysis of the female gland extract revealed two antennally active peaks. Using coupled gas chromatography–mass spectrometry (GC-MS), one was identified as (Z)-11-hexadecenal (Z11–16:Ald); however, further analysis on different types of capillary columns indicated that the second active compound has two different isomers, (E)-13-octadecenal (E13–18:Ald) and (Z)-13-octadecenal (Z13–18:Ald). The approximate ratio of E13–18:Ald, Z13–18:Ald and Z11–16:Ald in the crude pheromone gland extract was 10:1:0.1, respectively. Single sensillum recordings showed that there was one sensory neuron that responded with a high amplitude spike to both E13–18:Ald and Z13–18:Ald, while another neuron housed in the same sensillum responded to Z11–16:Ald. Field evaluation of the identified compounds indicated that the E13–18:Ald was necessary to evoke the attraction of males; although the presence of Z13–18:Ald and Z11–16:Ald increased the catches in traps. The highest number of caught males was achieved when E13–18:Ald, Z13–18:Ald and Z11–16:Ald were present in baits in the same ratio as in the female gland extract. This pheromone can be used in a monitoring strategy and could potentially lead to the development of mating disruption.