Papers by Dunja Leljak Levanic
Proceedings of Abstracts (Zbornik sažetaka), 9th Croatian Biological Congress, 2006
Food Technology and Biotechnology, 2011
Summary The extracellular proteins in three distinctly induced embryogenic lines of pumpkin (Cucu... more Summary The extracellular proteins in three distinctly induced embryogenic lines of pumpkin (Cucurbita pepo L.) cultivated in four MS media modified regarding the nitrogen composition or auxin presence/absence have been analyzed. Extracellular glycoproteins containing a-D-mannose were specifically detected by the lectine concavalin A. During the cultivation of embryogenic tissue in the medium supplemented with reduced nitrogen, the embryos were mostly arrested at preglobular and globular developmental stages, which coincide with the absence of protein secretion. Secreted glycoproteins of 76, 68, 37 and 34 kDa were detected only if any of the three lines were cultivated in the medium that stimulates embryo development, irrespectively of the addition of 2,4-dichlorophenoxyacetic acid or tunicamycin. The glycoprotein of 64 kDa was detected in all lines cultivated in hormone-free MS medium with conventional nitrogen sources and it appears to be associated with embryo maturation. Tunicam...
Vitis: Journal of Grapevine Research, 2019
A native Croatian grapevine 'Grk bijeli', sharing a parent-offspring relationships with &... more A native Croatian grapevine 'Grk bijeli', sharing a parent-offspring relationships with 'Tribidrag' (aka 'Zinfandel'), is grown exclusively on the Adriatic island of Korcula. It is one of the grape cultivars with female-only functional flowers, causing reduced fertilisation and leads to problems in grape production and wine quality. A typical cluster of 'Grk bijeli' at maturity contains fully developed seeded berries, in addition to a highly variable proportion of undersized seedless berries. The aim of this study was to identify the cause of the reduced reproduction potential of 'Grk bijeli' in order to establish a better growing environment for improved yield and grape quality. 'Grk bijeli' female gametophyte develops normaly and at maturity contains both egg and central cell, together with two synergid cells and three antipodal cells. On the other hand, 'Grk bijeli' pollen grains show developmental deviations. Specifically, ...
Food Technology and Biotechnology, 2002
Efficiency in transformation of three hybrids of Coleus blumei using wild and mutant strains of A... more Efficiency in transformation of three hybrids of Coleus blumei using wild and mutant strains of Agrobacterium sp. was evaluated. Successful transformation depended on specific bacterial strain-plant genotype combination and co-cultivation treatment. The wild type B6S3 of the bacterial strains employed gave the maximum efficiency. Strains C58C1(pArA4abc), GV3101(pGV2215), 8196 and A281 were also effective. Among several co-cultivation conditions tested, the most efficient treatment was as follows: excised leaf explants were incubated immeadiately in bacterial suspension for 5 min and were co-cultured with Nicotiana tabacum crown gall callus for two days. Plant hormone autotrophy, PCR analyses and hybridization analysis confirmed genetic transformation of the cultures. Sixteen different transgenic callus and cell cultures were maintaned for more than four years in the absence of exogenous growth regulators and antibiotics without deterioration in the growth rate.
Acta Botanica Croatica, 2001
The effects o f thidiazuron (TDZ) on adventitious shoot bud formation from leaf and peti ole exp... more The effects o f thidiazuron (TDZ) on adventitious shoot bud formation from leaf and peti ole explants excised from in-vitro-grown plantlets o f a begonia were tested by a two-step procedure: a short exposure (5 to 120 min) to 40 pM TDZ in liquid MS medium followed by culture on agar-solidified MS medium without growth regulators. Exposure of explains for five min to TDZ induced bud formation, but the number o f buds was in creased with prolonged exposure. Sixty min exposure to TDZ resulted in the highest mean number o f regenerated shoots (24/leaf disc: 44/petiole segment after five weeks o f cul ture). Shoots generated after two weeks in culture without, or with a small amount of, cal lus. During the third and fourth week in culture shoots developed small roots, and from the mother explant separated shoots elongated and further developed. The sucrose concentra tion in the basal expression medium influenced the efficiency of shoot organogenesis. The frequency of shoot formation...
Plants are a major source of natural products used as pharmaceuticals, agrichemicals, flavor and ... more Plants are a major source of natural products used as pharmaceuticals, agrichemicals, flavor and fragrance ingredients, food additives, etc. Most likely plants will continue to provide novel natural products as well as sources for new drugs in the coming centuries, since the chemistry of the majority of extant plant species remains to be characterized. The search for new plant-derived chemicals should thus be a priority in current and future efforts towards sustainable conservation and rational utilization of biodiversity. In vitro biology and technology have contributed toward production of plant natural products, via micropropagation, cell culture, scaled-up bioreactors, etc. Some examples of in vitro techniques used to achieve secondary metabolite synthesis are discussed. Preliminary results in achieving Coleus blumei transgenic tissue cultures and their capacity for synthesis of rosmarinic acid are also described.
Periodicum Biologorum, 2003
Background and Purpose: The large-scale use of Agrobactenum in conifer transformation has been li... more Background and Purpose: The large-scale use of Agrobactenum in conifer transformation has been limited by difficult propagation of explant materials. Cotiledonary somatic embryos present a target tissue with a high regeneration potential, receptive to the introduction of foreign DNA In order to develop an Agrobactenum-mediated transformation procedure for Picea omorika somatic embryos, the effects of different biotic factors were examined. Material and Methods: Cotiledonary somatic embryos were co-cultivated with A. tumefaciens strain LBA 4404 bearing the binary plasmid pBI121 and pBI101Dc3. Transformation frequency was evaluated using a histochemical staining procedure. Results and Conclusions: Infection of intact embryos was the most effective: 54% GUS-positive somatic embryos was observed after 30 days of growth on the selection medium. There was no significant difference in transient GUS expression when embryos and Agrobacterium were co-cultivated in the presence of acetosyringo...
Proembryo production in pumpkin can be induced by low concentrations of NH4Cl as a sole source of... more Proembryo production in pumpkin can be induced by low concentrations of NH4Cl as a sole source of nitrogen, or by 2, 4-D. Subsequent addition of nitrogen in the first case, and removal of auxin in the second, stimulate more advanced stages of embryo development. Proembryogenic cells from the two systems showed differences in growth parameters and patterns of callose deposition. The latter disappeared when the tissue was transferred onto a medium that enables late embryo development. The activities of soluble peroxidase (EC 1.11.1.7), esterase and phenylalanine ammonia-lyase, enzymes shown to be markers of stress response and embryo development, were the highest in tissue grown in NH4+-only medium which reflects highly proembryogenic state of the culture. Enzymatic activities decreased after buffering of the medium with MES, and additionally decreased after re-supply of different forms of nitrogen or in medium with 2, 4-D. The effect of L-glutamine on somatic embryogenesis was strong...
Konzervirane proteinske domene MATH i BTB zastupljene su u razlicitim proteinima u jednoj kopiji,... more Konzervirane proteinske domene MATH i BTB zastupljene su u razlicitim proteinima u jednoj kopiji, zajedno ili u kombinacij sa drugim tipovima domena. Poznate uloge proteinske domene BTB su utisavanje transkripcije, regulacija stanicnog skeleta kao i ubikvitinizacija/razgradnja. Za ubikvitinizaciju/razgradnju važna je prisutnost domene MATH N-terminalno od domene BTB. MATH domena određuje specificnost prema supstratu. Iako uloga MATH/BTB proteina nije potpuno jasna, njihova siroka rasprostranjenost i konzerviranost ukazuju na važne stanicne funkcije. Pretraživanjem cDNA biblioteke izoliraih neoplođenih jajnih stanica i dvostanicnih proembrija psenice pronasli smo prisutnost nekoliko potpuno novih transkripata. Dva od njih kodiraju proteine koji sadrže obje domene, MATH i BTB i pronađeni su ili u jajnoj stanici (TaMATH/BTB-Ec) ili u dvostanicnom proembriju (TaMATH/BTB-2c). Treci transkript koji kodira MATH/BTB protein (TaMATH/BTB) pokazuje homologiju sa vec poznatim transkriptima. Eks...
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Papers by Dunja Leljak Levanic