Effect of cytokinins on shoot apical meristem in Nicotiana tabacum

Cytokinins are involved in plant cell proliferation leading to plant growth and morphogenesis. The size, activity and maintenance of the shoot apical meristem (SAM) are defined by a balanced rate of mitotic cell divisions and functional cell differentiation that are controlled by cytokinins. In order to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical changes in the shoot apices of tobacco treated with benzyladenine (BA) were compared to those of untreated control plants

In vitro zygotic embryo culture of Pinus peuce Gris.: Optimization of culture conditions affecting germination and early seedling growth

This study reports a protocol for the germination and early seedling growth of Pinus peuce Gris. using zygotic embryo culture. In order to overcome seed dormancy and optimize organogenesis, the effect of nutritional, plant growth regulatory and physical factors on in vitro germination and growth of isolated mature zygotic embryos of P. peuce were investigated

Effect of development stage of Pinus heldreichii megagametophytes on the induction of embryogenic tissue

The potential of somatic embryogenesis induction was examined by in vitro growing of isolated ovules of Pinus heldreichii (Christ.) on nutrient media. The induction of embryogenic tissue was stimulated by Gresshoff and Doy (GD) medium with nitrogen compounds reduced to one half and with 0.5 mg/l BA and 2.0 mg/l 2.4-D. Still, the most important factor in this process was the development stage of embryos in the ovule. An induction frequency of 10% was obtained on the ovules in which embryos were in the pre-cotyledonary stage. When the dominant embryo in the ovule was in the cotyledonary stage, the induction frequency was lower or absent. Proliferation of embryogenic tissue was achieved on the media with reduced concentration of growth regulators, and the initial stages of embryo maturation were obtained on the media with ABA and 5% sucrose.Izolovane ovule Pinus heldreichii (Christ.) gajene su in vitro na hranljivim podlogama radi ispitivanja mogućnosti indukcije somatske embriogeneze. Hranljiva podloga Gresshoff and Doy (GD) sa azotnim jedinjenjima, smanjenim na polovinu i BA 0.5 mg/L i 2.4-D 2.0 mg/L, stimulisala je indukciju embriogenog tkiva. Ipak, najvažniji faktor u ovom procesu bio je stadijum razvića embriona u ovuli. Frekvencija indukcije od 10% dobijena je na ovulama u kojima su embrioni bili u prekotiledonarnom stadijumu razvića. Kada je dominantni embrion u ovuli bio u kotiledonarnom stadijumu razvića, frekvencija indukcije bila je manja ili je nije ni bilo. Proliferacija embriogenog tkiva dobijena je na podlogama sa smanjenom koncentracijom regulatora rastenja, a početni stadijumi sazrevanja embriona na podlogama sa ABA i 5% saharoze.Projekat ministarstva br. 143026

In vitro zygotic embryo culture of Pinus peuce Gris.: Optimization of culture conditions affecting germination and early seedling growth

This study reports a protocol for the germination and early seedling growth of Pinus peuce Gris. using zygotic embryo culture. In order to overcome seed dormancy and optimize organogenesis, the effect of nutritional, plant growth regulatory and physical factors on in vitro germination and growth of isolated mature zygotic embryos of P. peuce were investigated.Projekat ministarstva br.17301

Induction of somatic embryogenesis in Pinus heldreichii culture

The potential for somatic embryogenesis in zygotic embryo and megagametophyte cultures of Pinus heldreichii was examined. Somatic embryogenesis was initiated from megagametophytes containing immature zygotic embryos at early stages of development. An induction frequency of up to 6.7% was obtained on Gresshoff and Doy medium in the presence of 2 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/l benzyladenine (BA). Formation and further proliferation of embryogenic tissue were achieved upon transfer of explants to a medium with reduced levels of growth regulators. Somatic embryos are being cultured for further development. .U kulturi izolovanih zigotskih embriona i ovula munike (Pinus heldreichii) ispitivan je efekat hranljive podloge i regulatora rastenja na indukciju somatske embriogeneze. Somatska embriogeneza je indukovana u kulturi ovula koje su sadržavale embrione na ranom stupnju razvića. Najviša frekvencija indukcije od 6.7% postignuta je kada su ovule 5 dana gajene na Gresshoff i Doy (GD) hranljivoj podlozi u prisustvu 2,4-D 2 mg/l i BA 0.5 mg/l, a zatim prenete na GD podlogu u kojoj je koncentracija regulatora rastenja bila 5 puta niža. U cilju dugotrajnog održavanja u kulturi, embriogeno tkivo je izolovano i gajeno na GD podlozi sa 2,4-D 0.2 mg/l i BA 0.05 mg/l. Mikroskopskom analizom je utvrđeno da se tkivo sastoji od brojnih embriona na ranim stupnjevima razvića. Za klonalnu propagaciju ove značajne endemoreliktne četinarske vrste u kulturi in vitro, neophodna su dalja istraživanja sa ciljem povećanja frekvencije indukcije somatske embriogeneze, kao i frekvencije sazrevanja embriona. .nul

Populus x euramericana tension wood as a model for selection of microscopic methods for rapid screening of cell wall structure in the analysis of plant stem properties

The plant cell wall (CW) is a cell compartment lying outside the plasma membrane forming a continuum throughout the plant body. The composition of CWs varies between plant species and cell types, while changes in CW constituents occur as a result of growth and developmental processes, or as a response to various environmental stimuli. In the herein study, we present a selection of microscopic methods for rapid, relatively simple, and low-cost visualization of CW structure/composition in tissues of stems in trees, shrubs, or herbs. Selected microscopic methods imply the use of unfixed, intact, both fresh and dried, plant tissues for the analysis, as well as free-hand or microtome sectioning. UV microscopy, phloroglucinol-HCl and toluidine blue O staining, SEM microscopy, and RAMAN microspectroscopy, separately or in combination, can provide valuable information in plant ecology, plant physiology studies, or for applications in agronomy and forest products industry. As a model, stem samples of juvenile Populus x euramericana trees exposed to severe long term static bending were selected: tension wood fibers (gelatinous fibers, specialized sclerenchyma cells) could be considered as representatives of CWs with the most complex structure, while the genus Populus is considered as a model woody Angiosperm

Factors influencing germination and growth of isolated embryos of Pinus heldreichii

The effects of nutritional, hormonal, and physical factors on the germination and growth of isolated mature zygotic embryos of Pinus heldreichii were studied under in vitro conditions. The optimum medium for embryo germination and adequate conversion into seedlings was basal Gresshoff and Doy (1GD) medium. All tested carbohydrates at the applied concentrations stimulated embryo growth, but only 3% sucrose increased embryo germination compared to the control, while maltose had an inhibitory effect. Among the applied plant growth regulators, only gibberelic acid (GA3) had a few benefits on the development of isolated embryos into plantlets, while the others had a negative effect. Embryos cultured on an agar-solidified medium grew better and the germination percentage was higher than in a liquid medium. Light treatment did not affect embryo germination, but generally stimulated seedling growth.U kulturi in vitro ispitivan je efekat nutritivnih, hormonalnih i fizičkih faktora na klijanje i rastenje izolovanih zigotskih embriona munike (Pinus heldrechii). Većina izolovanih embriona munike klijala je već tokom prve nedelje nakon prenošenja na hranljivu podlogu. Mada embrioni mogu da klijaju i na podlozi bez soli, vitamina i ugljenih hidrata, najveći procenat klijanja i najbolje morfološke karakteristike klijanaca postignute su na bazalnoj Gresshoff & Doy podlozi (1GD) sa 3% saharozom. Od ispitivanih regulatora rastenja samo je giberelna kiselina (GA3) pozitivno delovala na razviće embriona, dok su auksini i citokinini inhibirali njihovo dalje razviće. U odnosu na embrione koji su rasli u tečnoj podlozi, embrioni sa čvrste agarne podloge, klijali su u većem procentu i dalje se pravilno razvijali. Mada generalno stimulišu rastenje klijanaca, svetlosni tretmani nisu imali efekat na klijanje embriona. Dobijeni rezultati pokazuju da se in vitro sistem može koristiti za brzu i sinhronu produkciju zdravih klijanaca elitnih genotipova koji se odlikuju niskom produkcijom semena.Projekat ministarstva br. 14302

Effect of cytokinins on shoot apical meristem in Nicotiana tabacum

Cytokinins are involved in plant cell proliferation leading to plant growth and morphogenesis. The size, activity and maintenance of the shoot apical meristem (SAM) are defined by a balanced rate of mitotic cell divisions and functional cell differentiation that are controlled by cytokinins. In order to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical changes in the shoot apices of tobacco treated with benzyladenine (BA) were compared to those of untreated control plants.Projekat ministarstva br. 17301

Enzymatic component of antioxidative system in succulent plant Tacitus bellus as a response to hemibiotroph Fusarium verticillioides infection in vitro

Fungi and plants interact in different ways, creating a scale of associations. Hemibiotrophic fungi represent the most interesting group, as they use sequential biotrophic and necrotrophic infection strategies. The co-evolution of plant and fungal life-styles has not been well characterized. We present changes of enzymatic component of antioxidative system in succulent plant Tacitus bellus that specifically correspond to subsequent phases (spore germination, biotrophic phase, and necrotrophic phase) of hemibiotroph Fusarium verticillioides infection. T. bellus response to F. verticillioides spore germination was characterized by transient increase in catalase (CAT), but decrease in superoxide dismutase (SOD) and peroxidase (POD) activity. During biotrophic phase of F. verticillioides infection, when hyphae spread intercellularly in epidermal and mesophyll tissue, host antioxidative system was suppressed. The transition from biotrophic to necrotrophic phase (inter and intracellular colonization and sporulation) triggered the host plant cells to create a highly defensive environment: CAT, SOD and POD activities were significantly stimulated, slowing, or even currently arresting, colonization of T. bellus mesophyll cells. CAT, showing the most pronounced activity increase, could be suggested as the main enzyme responsible for slowing the progression of necrotrophic phase of F. verticillioides growth. However, contrary to host CAT and SOD which isoenzyme profile didn’t change, new highly acidic POD isoforms replaced the two mildly acidic isoforms, suggesting their specific role in slowing the progression of infection. Presented results add to knowledge of events and mechanisms related to hemibiotrophic fungi pathogenicity in succulent plants grown under high relative humidity, similar to conditions in greenhouse

Uticaj suše na fiziološke odgovore biljaka kukuruza dobijenih iz semena različite starosti

Drought is one of the main consequences of climate change that negatively affects plant growth and development, which in turn leads to a reduction in yield. The objective of this study was to investigate the effects of the physiological responses to the drought stress of maize plants (population IP3722), obtained from seeds of different ages (originating from 2012. and 2016) and different previous experience (the seeds formed in 2012. were more exposed to drought than in 2016.). Two populations responded to drought treatment by a significant decrease of shoot fresh and dry weight, this was followed with decrease leaf area and transpiration rate. Drought treatments enabled induction and differentiation of chemical signals of drought (abscisic acid-ABA and xylem pH) and hydraulic signals (leaf water potential), and monitoring of their activity on stomatal conductance. The data showed that hydraulic signals have the same impact on stomatal reactions in the D2012 and D2016 treatments. They also indicated that the chemical signal of ABA works toward stomatal closure, but that the effect depends on whether it originates from the leaf or the root. Leaf-originating ABA had more effect on the closure of D2012 stomata, while root-originating ABA and pH was more active in the D2016.Suša nastaje kao posledica klimatskih promena, koja negativno utiče na rast i razvoj biljaka, a to dovodi do smanjenja prinosa. Cilj ovog rada bio je da se istraži efekat suše na fiziološke reakcije biljaka kukuruza (IP3722), koje su dobijene iz semena različite starosti (regenerisano 2012. i 2016.) i različitih prethodnih iskustava (semena koja su formirana 2012. su bila u većoj meri izložena suši nego ona iz 2016.). Suša je kod oba uzorka dovela do smanjenja sveže i suve mase nadzemnog dela biljke, što je bilo praćeno opadanjem lisne površine i stomatalne provodljivosti. Tretmanom suše su indukovani hemijski signali (ABA i pH) i hidraulički signal (vodni potencijal), koji su uticali na provodljivost stoma. Podaci su pokazali da hidraulički signal ima podjednak udeo na zatvaranje stoma u tretmanu D2012 i D2016. Takođe, ABA kao hemijski signal dovodi do zatvaranja stoma, ali ovaj efekat zavisi od toga da li ABA potiče iz korena ili lista. ABA poreklom iz lista je imala značajniji doprinos u zatvaranju stoma kod D2012, dok ABA poreklom iz korena i pH kod tretmana D2016