Institute of Plant Physiology

Main research topics

Role of fertilization rate (root or foliar applied nutrients) and combined application of growth regulators - thidiazuron (Dropp^®), 2,3,5-triiodobenzoic acid (Tiba^®), mepiquat chloride (Pix^®) and prohexadione-Ca (Regalis^®) during field cultivation of milk thistle (Silybum marianum L) plants on plant reproductive development, seed yield and silymarin content have been studied.
Dependence between the rate of mineral nutrition and symbiotic relationships in legumes regarding efficiency of nodulation, nitrogen fixation and mineral nutrient accumulation has been studied. Study on the alterations in triple symbiosis (Rhizobium-Legume-VAM infection) on nodulation efficiency and VAM infection caused by different rate of phosphate fertilization have been studied.
Cytoskeletal dynamics and microtubule-organizing centers in plant cells; symbiotic relationships between legume plants and nitrogen-fixing rhizobia; plant cell ultrastructure and physiology as related to the metabolic and functional capabilities of the cells.
Investigations of the role of chemical forms of copper and zinc on roots redox system activities, metabolic and antioxidant respones of hydroponically grown plants under mineral stress. Study of signalling pathways during expression of the remedying effect of metal chelates upon plant development under non-optimal growth conditions – iron deficiency and copper excess.
Comparison the effects of synthetic cytokinins and some phytoeffectors on the organogenesis and metabolic processes of excised cotyledons from Fagopyrum esculentum and Cucumis sativus seedlings.
Morphological, physiological and biochemical responses of some crop plants to some heavy metal toxic effects in order to elucidate the physiological mechanisms of plant tolerance was investigated.
The effect of different rate of fertilizer application (soil or foliar) on the accumulation and metabolism of nutrients in crop plants related regarding regulation of yield quantity and quality.

Most important achievements

The separation and partially purification of cupric- and ferric-chelate reductase activities, associated with solubilized plasma membranes (PM) of maize roots was achieved. The application of dye-ligand affinity and anion exchange chromatography steps revealed that the elution profiles during separation pointed out the involvement of different redox proteins with Cu(II)-chelate reductase activity using either NAD(P)H or ascorbate as electron donors and reacting differently with redox inhibitors and effectors.
A stimulating effect of copper ions and synthetic cytokinin chloro-pyridyl phenylurea on the plasma membrane redox system activity, growth and anthocyanin synthesis in excised buckwheat cotyledons was established.
Effects of nutrient supply, pH and some growth regulators in the medium on the formation and functioning of soybean (Glycine max L. Merr) - Bradyrhizobium japonicum, pea (Pisum sativum L.) - Rhizobium leguminosarum bv. vicae and Galega orientalis - Rhizobium galegae symbiotic relationships were assessed.
In vivo quantification of the dynamic instability parameters of GFP-labeled cortical microtubules in root hairs of Lotus japonicus, and comparison of microtubule dynamics in different developmental zones of root hairs, as well as upon application of purified Mesorhizobium loti Nod factors.
The negative effect of boron starvation on nodule formation and functioning in soybean seedlings was associated with the changes in the root and nodule cell membrane stability, rate of root exudation, ex planta migration and attachment ability of rhizobial cells towards root exudates. Inhibited CO₂ exchange rate of nodulated soybean leaves by boron starvation related to altered ¹⁴C assimilate partitioning, carbohydrate pool of leaves, root and nodules.
Phosphorus (P) deficiency and toxicity caused significant changes in the major phosphate fractions extracted from pea and soybean root, nodules and leaves. Phosphorus deficiency or toxicity exert negative effect on root PAL activity, concentrations of HPLC analyzed total and individual phenol and flavonoids in root exudates, rate of rhizobial nod D ABC expression ex planta and inhibition of nodulation and nitrogen fixation in symbiotic plants.
The manifestations of copper toxicity on the sub-cellular organization of root cells of maize plants were determined. High concentrations of copper in the medium led to nuclear structural alterations such as condensation of the chromatin fibrils and decreased DNA synthesis. The nucleolus morphological changes, expressed as segregation of the main components were viewed. They were observed as a result of the toxic effect of copper ions on the AG-NOR protein. All these changes were associated with the decrease of proliferate activity of the root meristem cells as well as a destruction in the membrane integrity of plasmalemma, endoplasmatic reticulum and mitochondria membranes.
Positive combined effects of foliar + root fertilization and growth regulators during milk thistle (Silybum marianum L.) cultivation in field on flowering rate, seed yield and quality was found to correlate with the increased nitrogen and carbohydrate metabolism in leaves during flowering stage.

Research projects

International projects:

Iron, zinc and copper plant mineral nutrition – physiological responses and adaptation under nonoptimal growth conditions. Project coordinator: Assoc. Prof. Nadejda Babalakova, Participant: Svetlana Boycheva.
The improvement of cultivation and yield production of some medicinal and aromatic plants by application of mineral nutrients and plant growth regulators. Joint research project with Egypt National Research Centre. Project coordinator: Assoc. Prof. Georgi I. Georgiev, Participants: Assoc. Prof. Ira Stancheva, Assist. Prof. Maria Geneva, Assist. Prof. Grigor Zehirov.
Improvement of the growth, seed yield and active substances of milk thistle plants (Silybum marianum L.). Joint research project with Charles University of Prague, Faculty of Phgarmacy in Hradec Kralove. Project coordinator: Assoc. Prof. Georgi I. Georgiev, Participants: Assoc. Prof. Ira Stancheva, Assist. Prof. Maria Geneva, Assist. Prof. Grigor Zehirov.
Study of phosphorus fractions in some soybean varieties, distinguished with different sensitivity to phosphorus nutrition. Joint research project with Chinese Academy of Sciences. Project coordinator: Assoc. Prof. Georgi I. Georgiev, Participants: Assoc. Prof. Ira Stancheva, Assist. Prof. Maria Geneva, Assist. Prof. Grigor Zehirov.

Projects funded by the National Science Fund - Ministry of education and science of Republic Bulgaria:

Physiology of manganese toxicity in maize and pea plants. The amelioration of manganese toxicity by silicon treatment (Contract Р-1524). Project coordinator: Assoc. Prof. Snejana Doncheva, Participant: Assist. Prof. Zlatimira Stoyanova.
Regulation of biological and economic yields quality of milk thistle plants (Silybum marianum) with plant growth regulators and mineral nutrition (Contract СС-1504). Project coordinator: Assoc. Prof. Georgi I. Georgiev, Participants: Assoc. Prof. Ira Stancheva, Assist. Prof. Maria Geneva, Assist. Prof. Grigor Zehirov.
Influence of copper ions and phytohormons on the growth and organogenesis of plant explants and some mutants of Arabidopsis (Contract B-1406). Project coordinator: Assoc. Prof. Ekaterina Stoinova, Participant: Assoc. Prof. Nadejda Babalakova.

Staff

In the Department are working 4 Associate Professors, PhD; 9 Assistant Professors, PhD and 8 Researchers.

To contact particular colleague please dial +359-2-979- followed by the extension number given below:

Name, Title	Contact Phone
Georgi Georgiev, Associate Professor, PhD	2689
Snezhana Doncheva, Associate Professor, PhD	2614
Nadejda Babalakova, Associate Professor, PhD	2602
Ira Stancheva, Associate Professor, PhD	2616
Veselina Nenova, Assistant Professor, PhD	2678
Valya Vassileva, Assistant Professor, PhD	3675
Zlatimira Stoyanova, Assistant Professor, PhD	3676
Maria Geneva, Assistant Professor, PhD	2675
Konstantina Kotcheva, Assistant Professor, PhD	3676
Grigor Zehirov, Assistant Professor, PhD	2675
Elisaveta Kirova, Assistant Professor, PhD	2692
Marieta Christozkova, Assistant Professor, PhD	2675
Svetlana Boycheva, Assistant Professor, PhD	2675
Ana Trifonova, Researcher	2692
Madlen Boychinova, Researcher	2692
Snezhana Rocheva, Researcher	2675
Mariana Sichanova , Researcher	2675
Janet Mincheva, Researcher	3673
Angelinka Petrova, Researcher	3674
Anelia Dimitrova, Researcher	3673
Martina Chavdarova , Researcher	3673

Selected publications

2009
Hristozkova, M., M. Geneva, M. Boychinova, I. Stancheva (2009) - Effect of foliar feeding on growth and nitrogen assimilatory enzymes in alfalfa plants at insufficient molybdenum supply. Acta Biologica Hungarica, 60(2), (in press).

2008
Geneva, M., G. Zehirov, I. Stancheva, L. Iliev, G.Georgiev (2008) - Effect of soil fertilizer, foliar fertilizer, and growth regulator application on milk thistle development, seed yield, and silymarin content. Communications of Soil Science and Plant Analysis, 39, 17-24.
Stancheva, I., Abd el Ghany Youssef, M. Geneva, L. Iliev, G.Georgiev (2008) - Regulation of Milk Thistle (Silybum marianum L.) Growth, Seed Yield and Silymarin Content with Fertilization and Thidiazuron Application. The European Journal of Plant Science and Biotechnology, 2(1), 94-98.
Stancheva I., G. Georgiev, M. Geneva, A. Ivanova, M. Dolezal, L. Tumova (2008) -. Influence of foliar fertilization and growth effector 5-tert-butyl-N-m-tolylpyrazine-2-carboxamide on the milk thistle (Silybum marianum L.) seed yield and quality. In : Proceedings of Fifth Conference on Medicinal and Aromatic Plants of Southeast European Counties. (5^th CMAPSEEC), Brno 2-5. 09.2008. Published by Mendel University of Agriculture and Forestry Brno.
Hristozkova, M., M. Geneva, I. Stancheva (2008) - Effects of Sinorhizobium meliloti strains (1021 and NitR) on nitrogen assimilation of alfalfa plants under conditions of mineral elements shortage. Gen. Appl. Plant Physiology, Special Issue, (in press).
K. V. Kocheva and G. I. Georgiev (2008) - Changes in Foliar Proline Concentration of Osmotically Stressed Barley. Z. Naturforsch., 63c, 101-104.
Stoyanova Zl., E. Zozikova, C. Poschenrieder, J. Barcelo, S. Doncheva (2008) - The effect of silicon on the symptoms of manganese toxicity in maize plants. Acta Biologica Hungarica, ( in press).
Doncheva Sn., C. Poschenrieder, Zl. Stoyanova , K. Georgieva , M. Velichkova , J. Barceló (2008) - Silicon amelioration of manganese toxicity in Mn-sensitive and Mn tolerant maize varieties. Environm. Exp. Bot., (in press).
Kalina Ananieva, Evgueni D. Ananiev, Snejana Doncheva, Katya Georgieva, Nikolina Tzvetkova, Miroslav Kamınek, Vaclav Motyka, Petre Dobrev, Silvia Gajdosova and Jiri Malbeck (2008) - Senescence progression in a single darkened cotyledon depends on the light status of the other cotyledon in Cucurbita pepo. (zucchini) seedlings: potential involvement of cytokinins and cytokinin oxidase/dehydrogenase activity Physiologia Plantarum, 2008, ISSN 0031-9317, (in press).
Nenova, V. (2008) - Growth and mineral concentrations of pea plants under different salinity levels and iron supply. General and Applied Plant Physiology, Special Issue, (in press).
Nenova, V. (2008) - Growth and photosynthesis of pea plants under different iron supply. Acta Physiologiae Plantarum, (in press).
Nenova, V., M. Merakchiyska, G. Ganeva, E. Zozikova, S. Landjeva (2008) - Physiological responses of wheat (Triticum aestivum L.) - Aegilops sharonensis introgression lines to excess copper. Journal of Agronomy and Crop Science, (in press).
Svetlana Boycheva, Nadejda Babalakova, Snejka Rocheva (2008) - Impact of ionic and chelated copper on the reductase activities in roots of iron-deficient cucumber plants. Comptes rendus de l'Academie bulgare des Sciences, 61(7), 891-898.
Svetlana Boycheva, Nadejda Babalakova (2008) - Does chelated copper ameliorate the greening of iron-deficient cucumber plants through nitric oxide signaling? Comparison with chemical forms of zinc. General and Applied Plant Physiology, Special Issue, (in press).
E. Kirova, N. Tzvetkova, I. Vasseva, G. Ignatov (2008) - Photosynthetic Responses of Nitrate-fed and Nitroden-fixing Soybeans to Progessive water stress. J. Plant Nutrition, 31:445-458.
Demirevska, K., L. Simova-Stoilova, V. Vassileva, U. Feller (2008) - Rubisco and some chaperone protein responses to water stress and rewatering at early seedling growth of drought sensitive and tolerant wheat varieties. Plant Growth Regulation, 56: 97-106.
De Smet, I., V. Vassileva, B. De Rybel, M.P. Levesque, W. Grunewald, D. Van Damme, G. Van Noorden, M. Naudts, G. Van Isterdael, R. De Clercq, J.Y. Wang, N. Meuli, S, Vanneste, J. Friml, J., P. Hilson, G. Jürgens, G.C. Ingram, D. Inzé, P.N. Benfey, T. Beeckman (2008) - Receptor-like kinase ACR4 restricts stem cell divisions in the Arabidopsis root. Science, 322, 5901: 594-597.
Demirevska, K., L. Simova-Stoilova, V. Vassileva, I. Vaseva, B. Grigorova, U. Feller (2008) - Drought induced leaf protein alterations in sensitive and tolerant wheat varieties. Gen. Appl. Plant Physiol., Special Issue 34, 1-2, 79-102.
Jansen, L., B. Rybel, V. Vassileva, Tom Beeckman (2008) - Root development. In: Pua, E.C., Davey, M.R. (Eds.), Plant Developmental Biology – Biotechnological Perspecives, Springler, Heidelberg, Germany (in press).

2007
Kocheva, K., G. I. Georgiev, R. V. Vunkova-Radeva (2007) - Contribution of mineral nutrition to the response of barley seedlings to PEG-induced mild water stress. J. of Plant Nutr. Soil Science, 170, (3), 392-397.
Hristozkova, M., M. Geneva, I. Stancheva, G. Georgiev (2007) - Nitrogen assimilatory enzymes and amino acid content in inoculated foliar fertilized pea plants grown at reduced molybdenum concentration. J. Plant Nutr., 30, (9) 1409-1419.
Tsvetkova, G., G. I. Georgiev (2007) - Changes in phosphate fractions extracted from different organs of phosphorus starved nitrogen fixing pea plants (Pisum sativum L.). J. Plant Nutr., 30 (12) 2129–2140.
Hristozkova, M., M. Geneva, I. Stancheva, G. Georgiev (2007) - Nitrogen assimilatory enzymes and amino acid content in inoculated foliar fertilized pea plants grown at reduced molybdenum concentration. J. Plant Nutr., 30(5), (in press).
Hristoskova M., M. Geneva, I. Stancheva, G. Georgiev (2007) - Response of inoculated foliar fed pea plants (Pisum sativum L.) to reduced Mo supply. Acta Biol. Hungarica, 58, 1, 87-92.
Kocheva, K., G. I. Georgiev, R. V. Vunkova-Radeva (2007) - Contribution of mineral nutrition to the response of barley seedlings to PEG- induced mild water stress. J. of Plant Nutr. Soil Science, 170, (in press).
Tsvetkova, G., G. I. Georgiev (2007) - Changes in phosphate fractions extracted from different organs of phosphorus starved nitrogen fixing pea plants (Pisum sativum L.). J. Plant Nutr., (in press).

2006
Tsvetkova, G., T. Teofilova, G. I. Georgiev (2006) - Effect of naringenin and quercetin on transcriptional activity of Nod ABC genes of strain D293 and following nodulation and nitrogen fixation responses of inoculated pea plants (Pisum sativum L.). General and Applied Plant Physiology, Special issue, 67-71.
Boycheva, S. V., N. K. Babalakova (2006) - Reactions of root plasma membrane redox activities in iron-deficient cucmber plants after application of ionic and chelated copper. Acta Biologica Szegediensis, 50(1-2), 49-54.
Doncheva S., Z. Stoyanova, K. Georgieva, D. Nedeva, R. Dikova, G. Zehirov, A. Nikolova (2006) - Exogenous succinate increases resistance of maize plants to copper stress. J. Plant Nutr. Soil Sci., 169, 247-254.
Demirevska-Kepova K., Simova-Stoilova L., Stoyanova Z., Feller U. (2006) - Cadmium stress in barley: growth, leaf pigment and protein composition and detoxification of reactive oxygen species. J. Plant Nutr., 29, 3, 451-469.
Hristozkova, M., I. Stancheva, M. Geneva (2006) - Response of pea plants (Pisum sativum L.) to reduced supply with Mo and Cu. International Journal of Agriculture and Biology, 8(2) 218-220.
Geneva, M., G. Zehirov, E. Djonova, N. Kaloyanova, G. Georgiev, I. Stancheva (2006) - The effect of inoculation of pea plants with mycorrhizal fungi and Rhizobium on N and P assimilation. Plant, Soil and Environment, 52, 10, 435-440.
Tsvetkova, G., T. Teofilova, G. I. Georgiev (2006) - Effect of naringenin and quercetin on transcriptional activity of Nod ABC genes of strain D293 and following nodulation and nitrogen fixation responses of inoculated pea plants (Pisum sativum L.). General and Applied Plant Physiology, Special issue, (in press).
Zehirov, G., G. I. Georgiev (2006) - Relationships between cell membrane stability, exudate content and infectivity of Bradyrhizobium japonicum strain 639 to boron starved soybean plants. Acta Physiol. Plantarum, 28, 2, 171-179.

2005
Babalakova, N. K., D. D. Moskova, E. Hassan (2005) - Modulation of plasma membrane redox-activities and growth of Fagopyrum esculentum M. excised cotyledons after application of synthetic cytokinin and copper ions. Egyptian J. Agric. Res., 2(1), 169-184.
Babalakova N., S. Boycheva, S. Rocheva (2005) - Effects of short-term treatment with ionic and chelated copper on membrane redox-activity induction in roots of iron-deficient cucumber plants. General and Applied Plant Physiology, 31(3-4), 143-155.
Vassileva, V. N., H. Kouchi, R. W. Ridge (2005) - Microtubule dynamics in living root hairs: transient slowing by lipochitin oligosaccharide nodulation signals. Plant Cell, 17, 1777-1787.
Vassileva, V. N., Y. Fujii, R. W. Ridge (2005) - Microtubule dynamics in plants. Plant Biotechnology, 22, 171-178.
Doncheva, D., K. Georgieva, V. Vassileva, Z. Stoyanova, N. Popov, G. Ignatov (2005) - Effects of succinate on manganese toxicity in pea plants. J. Plant Nutr., 28, 47-62.
Simova-Stoilova L., Demirevska-Kepova K., Stoyanova Z. (2005) - Antioxidative protection in the leaves of dark-senescing intact barley seedlings. Acta Physiol. Plantarum, 27(3В), 349-356.
Miteva, E., D. Christova, V. Nenova, S. Maneva (2005) - Arsenic as a factor affecting virus infection in tomato plants. Changes in plant growth, peroxidase activity and chloroplasts pigments. Scientia Horticulturae, 105, 343-358.
Kirova, E., D. Nedeva, A. Nikolova, G. Ignatov (2005) - Change in the biomass production and total soluble protein spectra of nitrate-fed and nitrogen-fixing soybeans subjected to gradual water stress. Plant Soil Environ., 51(5), 237-242.
Kocheva, K., G. I. Georgiev, V. Kochev (2005) - A diffusion approach to the electrolyte leakage from plant tissues. Physiol. Plantarum, 125, 1-9.
Kocheva, K., M. Busheva, G. I. Georgiev, P. Lambrev, V. Goltsev (2005) - Influence of short-term osmotic stress on the photosynthetic activity of barley seedlings. Biol. Plantarum, 49, 1, 145-148.

2004
Babalakova, N. K., R. N. Kambourova, S. Rocheva (2004) - Iron deficiency impact on root redox-system activities and some antioxidant enzymes in cucumber plants. Comp. Rend. Acad. bulg. Sci., 57(4), 69-74.
Babalakova, N. K., S. N. Rocheva (2004) - Ascorbate oxidation and peroxidation in iron-deficient cucumber roots after short-term copper treatment. Comp. Rend. Acad. bulg. Sci., 57(7), 85-92.
Landjeva, S., G. Angelov, V. Nenova, M. Merakchiyska, G. Ganeva (2004) – Seedling growth and peroxidase responses to excess copper in wheat – Aegilops geniculata hromosome addition and substitution lines. Genetics and Breeding, 33(3-4), 17-24.
Atanasova, L., M. Pissarska, G. Popov, G. I. Georgiev (2004) - Growth and endogenous cytokinins of juniper shoots as affected by high metal concentrations. Biol. Plantarum, 48, 1, 157-159.
Kocheva, K., P. Lambrev, G. I. Georgiev, V. Goltsev, M. Karabaliev (2004) - Evaluation of chlorophyll fluorescence and membrane injury in the leaves of barley cultivars under osmotic stress. Bioelectrochemistry, 63, 121-124.