Effects of low temperature,genotype and culture media on in vitro androgenic answer of pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.)

Anther culture is one of the most important and useful tool to create pure lines for plant breeding programs rapidly. Some pepper genotypes are recalcitrant and embryogenic frequency in anther culture is still low or reaction is not observed at all. Temperature stress (low or high) can facilitate switching the microspore to sporophyte developmental pathway. In this study, some differences were found in embryogenic reaction among the pepper genotypes and culture media variants, depending on duration of cold treatment of flower buds. Experimental results indicated that embryogenic efficiency decreased under low-temperature stress. Nevertheless, positive effect of cold pretreatment on direct embryo induction was obtained in four genotypes—cultivar Hebar, hybrid 50/01 and lines 668/02 and 1312/02. Increasing of embryogenic reaction after cold pretreatment was observed in media variants C (24 h) and MS-3 + (24 and 48 h), while on medium variant C-0 direct embryo formation was registered only after 48 h cold pretreatment. These results show that the donor genotypes have specific requirements for type and duration of temperature pretreatment and also culture media for induction of androgenesis with higher frequency.     

Differential expression of β-glucosidase in tomato — stress stimuli systems

In the present work the responses of β-glucosidase in leaves of tomato plants subjected to various stress factors of both pathogenic (fungi, bacteria, viruses) and abiotic origin (heat shock) were studied. Biochemical and cytochemical methods were applied. It was established that an increase of β-glucosidase activity is induced uniquely by fungal pathogens. The cytochemical tests confirm the finding. Hence, the conclusion can be drawn that β-glucosidase response is a specific character of fungal pathogenesis in tomato; probably, the enzyme is involved in plant — fungi recognition. The data are in accordance with our previous results on tobacco and wheat — stress stimuli systems.     

Synthesis and biological activity of new series of N-modified analogues of the N/OFQ(1–13)NH2 with aminophosphonate moiety

New series of N-modified analogues of the N/OFQ(1-13)NH(2) with aminophosphonate moiety have been synthesized and investigated for biological activity. These peptides were prepared by solid-phase peptide synthesis-Fmoc-strategy. The N/OFQ(1-13)NH(2) analogues were tested for agonistic activity in vitro on electrically stimulated rat vas deferens smooth-muscle preparations isolated from Wistar albino rats. Our study has shown that the selectivity of the peptides containing 1-[(methoxyphosphono)methylamino]cycloalkanecarboxylic acids to the N-side of Phe is not changed-they remain selective agonists of NOP receptors. The derivative with the largest ring (NOC-6) demonstrated efficacy similar to that of N/OFQ(1-13)NH(2), but in a 10-fold higher concentration. The agonistic activity of newly synthesized N-modified analogues of N/OFQ(1-13)NH(2) with aminophosphonate moiety was investigated for the first time.     

Synthesis, structure and antimicrobial activity of manganese(II) and cobalt(II) complexes of the polyether ionophore antibiotic Sodium Monensin A

Mononuclear neutral manganese(II) and cobalt(II) complexes with the antibiotic Sodium Monensin A (Mon-Na, 1b) were synthesized and characterized. The crystal structures of M(Mon-Na)2Cl2.H2O (M=Mn, 2; M=Co, 3) were determined by X-ray crystallography. The complexes crystallize in monoclinic space group C2 with a tetrahedrally coordinated transition metal attached to oxygen atoms of deprotonated carboxyl groups of two Sodium Monensin molecules and two chloride ions. The sodium ion remains in the cavity of the ligand and cannot be replaced by Mn(II) or Co(II). The complexes were additionally characterized by different spectroscopic techniques (UV-Visible, EPR, FAB-MS). A preferable octahedral environment around the transition metal centers is observed in polar solvents while the complexes retain their tetrahedral structure in non-polar media. The antimicrobial activity of 1b, 2 and 3 was tested against Gram(+) and Gram(-) bacteria.     

Synthesis and biological activity of nociceptin/orphanin FQ(1-13)NH2 analogues modified in 9 and/or 13 position

The purpose of the present study was the synthesis and the biological screening of new analogues of N/OFQ(1-13)NH2, the minimal sequence maintaining the same activity as the natural peptide nociceptin. In order to investigate the role of Lys, we substituted Lys at positions 9 and/or 13 by Orn, Dab (diaminobutanoic acid) or Dap (diaminopropanoic acid). The new N/OFQ(1-13)NH2 analogues exerted strong and naloxone-resistant inhibition of electrically evoked contractions of rat vas deferens. Lys replacement with Orn maintained or even enhanced the inhibitory activity, while replacements with Dab and Dap decreased inhibitory activity.     

Anther culture in pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) in vitro

Pepper (Capsicum annuum L.) is an important vegetable crop that can be improved using plant tissue culture and biotechnology. However, it is difficult to develop appropriate breeding material by in vitro cultivation in this species. Haploid plant production is useful in the breeding programs to facilitate recovery of recessive mutations and unique genetic recombinations. In embryogenesis, haploid formation from pollen in anther culture is a scientifically advanced, but controversial system. Various techniques for haploid plant regeneration are used to establish an efficient double haploid production method. The purpose of this article is to summarize, through comparison, results in pepper anther culture, problems associated with work in this field, and the influence of critical factors for successful embryo formation and plantlet development.     

Umbel Browning and Stem Necrosis: a New Disease of Fennel in Bulgaria

A new fungal disease on fennel has been observed with increasing frequency in Bulgaria. The main symptoms were expressed as umbel browning and stem necrosis. Umbels could be destroyed completely and produced no fruits. Stem necrosis observed in the second and subsequent years of cultivation caused death of many twigs or whole plants. Pycnidia containing alpha and beta conidia developed on diseased umbels, twigs and stems. Perithecia with mature ascospores were found in vivo on the overwintered plant parts, and in vitro mainly on malt yeast extract agar and oatmeal agar. Diaporthe angelicae (anamorph Phomopsis foeniculi) was established as the causal agent. Isolates showed great variability in colony colour, linear growth, quantity of pycnidia and ability to produce teleomorph in vitro. Isolates obtained from fennel were able to infect other species belonging to the Apiaceae family, making the disease a potential threat for them, too.     

Engineering of the membrane of fibroblast cells with virus-specific antibodies: A novel biosensor tool for virus detection

A novel concept for the assay of viral antigens is described. The methodological approach is based on a membrane-engineering process involving the electroinsertion of virus-specific antibodies in the membranes of fibroblast cells. As a representative example, Vero fibroblasts were engineered with antibodies against Cucumber mosaic virus (CMV) and used for the construction of an ultra-sensitive miniature cell biosensor system. The attachment of a homologous virus triggered specific changes to the cell membrane potential that were measured by appropriate microelectrodes, according to the principle of the bioelectric recognition assay (BERA). No change in the membrane potential was observed upon cell contact with the heterologous cucumber green mottle mosaic virus (CGMMV). Fluorescence microscopy observations showed that attachment of CMV particles to membrane-engineered cells was associated with membrane hyperpolarization and increased [Ca(2+)](cyt). In an additional field-based application, we were able to detect CMV-infected tobacco plants at an essentially 100% level of accuracy.     

Metabolic changes in tomato fruits and seeds after viral, bacterial and fungal infections

The metabolic changes in tomato fruits and seeds separately infected with cucumber mosaic virus, Pseudomonas syringae pv. tomato or Botrytis cinerea were investigated cytochemically. The changes of peroxidase (E.C. 1.11.1.7) and β-glucosidase (E.C. 3.2.1.21) were investigated biochemically as well. Tomato fruits were involved in the study because of their high economic value. Tomato seeds were investigated since they have been used most extensively as a model system for studying the physiology and biochemistry of seed development. The diseases caused by the pathogens under study are of special importance for yield reduction in tomato. The three pathogens provoked local changes in the activities of enzymes under study that affect the infected pericarp tissues and neighboring seeds. It was established non-specific and specific responses. The non-specific responses of invaded tissues were expressed as a local enhancement of peroxidase activity in both pericarp tissues and seeds as well as a decrease in activities of: i. enzymes taking part in aerobic and anaerobic respiration, ii. hydrolases esterase and acid phosphatase involved in the basic metabolism as well as an enhancement of their activities in neighboring tissues. Furthermore, it was observed an enhancement of α-galactosidase activity in infected area was observed. The specific responses depending on the type of the pathogen consisted in an enhancement of glucose-6-phosphate dehydrogenase activity by virus infection and an increase of β-glucosidase activity by fungal invasion.     

Response of β-Glucosidase to Fungal Infections in Seed, Ovary and Fruit

Localization and changes in the activity of -glucosidase were investigated in wheat caryopsis and glumes infected with Stagonospora nodorum as well as in lily ovaries and harvested tomato fruits both inoculated with Botrytis cinerea. It was established that the pathogen invasion caused splitting of wheat seed coat, xylem blocking in lily carpel and decay in tomato fruits. B. cinerea invasion evoked disorders of the embryogenesis accompanied by a decreased activity of -glucosidase in all ovules. The activity of the enzyme was not changed considerably in wheat seeds as the infection occurred in the late embryonal stages and the embryonal processes were not affected. In the seeds of harvested tomatoes distant from the invaded area the enzyme activity was not changed as well.