1. 1-aminocyclopropane-1-carboxylate oxidase induction in tomato flower pedicel phloem and abscission related processes are differentially sensitive to ethyleneMarko Chersicola, Aleš Kladnik, Magda Tušek-Žnidarič, Tanja Mrak, Kristina Gruden, Marina Dermastia, 2017, izvirni znanstveni članek Povzetek: Ethylene has impact on several physiological plant processes, including abscission, during which plants shed both their vegetative and reproductive organs. Cell separation and programmed cell death are involved in abscission, and these have also been correlated with ethylene action. However, the detailed spatiotemporal pattern of the molecular events during abscission remains unknown. We examined the expression of two tomato ACO genes, LeACO1, and LeACO4 that encode the last enzyme in ethylene biosynthesis, 1-aminocyclopropane-1-carboxylate oxidase (ACO), together with the expression of other abscission-associated genes involved in cell separation and programmed cell death, during a period of 0–12 h after abscission induction in the tomato flower pedicel abscission zone and nearby tissues. In addition, we determined their localization in specific cell layers of the flower pedicel abscission zone and nearby tissues obtained by laser microdissection before and 8 h after abscission induction. The expression of both ACO genes was localized to the vascular tissues in the pedicel. While LeACO4 was more uniformly expressed in all examined cell layers, the main expression site of LeACO1 was in cell layers just outside the abscission zone in its proximal and distal part. We showed that after abscission induction, ACO1 protein was synthesized in phloem companion cells, in which it was localized mainly in the cytoplasm. Samples were additionally treated with 1-methylcyclopropene (1-MCP), a competitive inhibitor of ethylene actions, and analyzed 8 h after abscission induction. Cell-layer-specific changes in gene expression were observed together with the specific localization and ethylene sensitivity of the hallmarks of cell separation and programmed cell death. While treatment with 1-MCP prevented separation of cells through inhibition of the expression of polygalacturonases, which are the key enzymes involved in degradation of the middle lamella, this had less impact on the occurrence of different kinds of membrane vesicles and abscission-related programmed cell death. In the flower pedicel abscission zone, the physical progressions of cell separation and programmed cell death are perpendicular to each other and start in the vascular tissues.
Ključne besede: abscission, ACO, cell separation, ethylene, laser microdissection, programmed cell death, tomato, ultrastructure
Objavljeno v DiRROS: 24.07.2024; Ogledov: 83; Prenosov: 103
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3. How beech provenance affects the structure of secondary xylem, leaf traits, and the ectomycorrhizal community under optimal growth conditionsTanja Mrak, Jožica Gričar, Tina Unuk Nahberger, Gregor Božič, Luka Krajnc, Peter Prislan, Domen Arnič, Tom Levanič, Hojka Kraigher, 2024, izvirni znanstveni članek Povzetek: Beyond growth parameters and drought tolerance, comparatively little is known about the functioning of different beech (Fagus sylvatica L.) provenances. We investigated properties of leaves, stem secondary xylem, and ectomycorrhiza (ECM), and explored their interdependencies to identify the best performing beech provenance in optimal growth conditions. The study was conducted on 23-year-old trees in a provenance trial. The investigated provenances originated from Atlantic (Belgium—BE), Alpine (Italy—IT, Slovenia—SI), and continental climates (the Czech Republic—CZ). A significant effect of provenance was observed for stem vessel diameters and conductive area, as well as for foliar %C, δ13C, δ15N, and δ18O. δ13C as a proxy of intrinsic water use efficiency (iWUE) showed that the highest iWUE was achieved in BE provenance. Individuals with a better iWUE had wider growth rings regardless of provenance. Better iWUE was associated with lower specific leaf area (SLA). ECM community composition and diversity indices did not differ significantly among the provenances. Specific ECM taxa were associated with individuals with high SLA, δ13C, δ15N, and δ18O. In optimal growth conditions with no stress events, BE is a promising provenance due to an efficient water conducting system with high vessel diameters and conductive area, and high iWUE, while Alpine provenances showed an adaptation of their water conducting system to freezing conditions at their original locations. Integrating findings from different compartments improves our understanding of functioning of different beech provenances.
Ključne besede: Fagus sylvatica, provenance trial, stable isotopes, specific leaf area, xylem vessels, ectomycorrhizal fungi
Objavljeno v DiRROS: 19.04.2024; Ogledov: 346; Prenosov: 743
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4. Description, identification, and growth of Tuber borchii Vittad. mycorrhized Pinus sylvestris L. seedlings on different lime contentsTanja Mrak, Tine Grebenc, Silke Friedrich, Babette Münzenberger, 2024, izvirni znanstveni članek Povzetek: Tuber borchii forms ectomycorrhiza with oaks, hazel, and pines, including Pinus sylvestris. However, its ectomycorrhiza morphotype with P. sylvestris was not comprehensively described so far, and molecular analyses are missing despite a high danger of misidentification of T. borchii ectomycorrhiza with other closely related and less valuable truffle species. We described for the first time the morphology and anatomy of T. borchii-P. sylvestris ectomycorrhiza using differential interference contrast technique and semi-thin sections in combination with molecular confirmation of identity. Color of ectomycorrhiza is reddish to dark brown, and morphotypes are unevenly but densely covered by warts-bearing pin-like cystidia. All layers of the hyphal mantle are pseudoparenchymatous with outer mantle layer formed of epidermoid cells. T. borchii ectomycorrhiza was identified by a molecular comparison with fruitbodies used for inoculation and its respective ectomycorrhizae. T. borchii has a wide ecological amplitude. To get a better insight in mycorrhization requirements, we investigated growth of P. sylvestris and its ectomycorrhiza infection rate with T. borchii in substrate with different lime content. The mycorrhization of P. sylvestris with T. borchii in the mycorrhization substrate and cultivation in greenhouse conditions was successful, with colonization of P. sylvestris varying between 36.5 and 48.1%. There was no significant correlation of mycorrhization to applied lime contents, and consequently to pH in substrate, while the increased levels of lime improved growth of the P. sylvestris seedlings.
Ključne besede: root anatomy, ectomycorrhiza, Limestone content, molecular identification, Pinus sylvestris, Tuber borchii
Objavljeno v DiRROS: 22.01.2024; Ogledov: 580; Prenosov: 357
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5. Buckwheat milling waste effects on root morphology and mycorrhization of Silver fir seedlings inoculated with Black Summer Truffle (Tuber aestivum Vittad.)Tina Unuk Nahberger, Tine Grebenc, Daniel Žlindra, Tanja Mrak, Matevž Likar, Hojka Kraigher, Zlata Luthar, 2022, izvirni znanstveni članek Povzetek: Large amounts of buckwheat waste are generated annually by the industry and are used in several different ways. To date, there has been little research regarding its suitability as a medium for growing seedlings in nurseries. The aim of this study was therefore to analyze the suitability of common and Tartary buckwheat wastes (brans and husks) as media used for raising seedlings. A pot experiment with five different treatments was carried out, in which silver fir root parameters were analyzed and compared 6 and 12 months after summer truffle-spore inoculation. A significantly higher concentration of the antioxidant rutin was confirmed in Tartary buckwheat bran compared to other buckwheat waste used. We also confirmed a significantly positive effect of added Tartary buckwheat husks on specific root length, root tip density, and specific root tip density compared to added common buckwheat husks or Tartary buckwheat bran, for which a significantly negative effect on branching density was confirmed. A significantly negative effect of added buckwheat husks and Tartary buckwheat bran was confirmed for summer truffle mycorrhization level.
Ključne besede: buckwheat waste, root growth, summer truffle, forest nursery, silver fir, inoculation with ectomycorrhizal fungi
Objavljeno v DiRROS: 09.02.2022; Ogledov: 1095; Prenosov: 715
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6. Priročnik za določanje korenin olesenelih rastlinTanja Mrak, Jožica Gričar, Peter Železnik, Hojka Kraigher, 2016, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: določevalni ključi, znanstvene monografije, morfologija rastlin, anatomija rastlin, drobne korenine, EUFORINNO
Objavljeno v DiRROS: 03.11.2021; Ogledov: 879; Prenosov: 0 |
7. Ectomycorrhiza between Scleroderma Areolatum Ehrenb. and Fagus sylvatica L.Tanja Mrak, Katja Kühdorf, Tine Grebenc, Ines Štraus, Marko Bajc, Nada Žnidaršič, Babette Münzenberger, Hojka Kraigher, 2015, objavljeni povzetek znanstvenega prispevka na konferenci Objavljeno v DiRROS: 03.11.2021; Ogledov: 1007; Prenosov: 327
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9. Isotopic and water relation responses to ozone and water stress in seedlings of three oak species with different adaptation strategiesClaudia Cocozza, Elena Paoletti, Tanja Mrak, Saša Zavadlav, Tom Levanič, Hojka Kraigher, Alessio Giovannelli, Yasutomo Hoshika, 2020, izvirni znanstveni članek Povzetek: The impact of global changes on forest ecosystem processes is based on the species-specific responses of trees to the combined effect of multiple stressors and the capacity of each species to acclimate and cope with the environment modification. Combined environmental constraints can severely affect plant and ecological processes involved in plant functionality. This study provides novel insights into the impact of a simultaneous pairing of abiotic stresses (i.e., water and ozone (O3) stress) on the responses of oak species. Water stress (using 40 and 100% of soil water content at field capacity - WS and WW treatments, respectively) and O3 exposure (1.0, 1.2, and 1.4 times the ambient concentration - AA, 1.2AA, and 1.4AA, respectively) were carried out on Quercus robur L., Quercus ilex L., and Quercus pubescens Willd. seedlings, to study physiological traits (1. isotope signature [delta 13C, delta 18O and delta 15N], 2. water relation [leaf water potential, leaf water content], 3. leaf gas exchange [light-saturated net photosynthesis, Asat, and stomatal conductance, gs]) for adaptation strategies in a Free-Air Controlled Exposure (FACE) experiment. Ozone decreased Asat in Q. robur and Q. pubescens while water stress decreased it in all three oak species. Ozone did not affect delta 13C, whereas delta 18O was influenced by O3 especially in Q. robur. This may reflect a reduction of gs with the concomitant reduction in photosynthetic capacity. However, the effect of elevated O3 on leaf gas exchange as indicated by the combined analysis of stable isotopes was much lower than that of water stress. Water stress was detectable by delta 13C and by delta 18O in all three oak species, while delta 15N did not define plant response to stress conditions in any species. The delta 13C signal was correlated to leaf water content (LWC) in Q. robur and Q. ilex, showing isohydric and anisohydric strategy, respectively, at increasing stress intensity (low value of LWC). No interactive effect of water stress and O3 exposure on the isotopic responses was found, suggesting no cross-protection on seasonal carbon assimilation independently on the species adaptation strategy.
Ključne besede: ozone, gas exchange, English oak, holm oak, downy oak, Quercus ilex L., Quercus robur L., Quercus pubescens Willd
Objavljeno v DiRROS: 11.08.2020; Ogledov: 1952; Prenosov: 1175
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10. Elevated ozone prevents acquisition of available nitrogen due to smaller root surface area in poplarTanja Mrak, Klemen Eler, Ovidiu Badea, Yasutomo Hoshika, Elisa Carrari, Elena Paoletti, Hojka Kraigher, 2020, izvirni znanstveni članek Povzetek: Aims Poplars are ecologically and economically important tree genus, sensitive to ozone (O3). This study aimed to investigate modifying effects of elevated O3 on poplar root response to nutrient addition. Methods In pot experiment, young trees of an O3-sensitive Oxford poplar clone (Populus maximoviczii Henry x berolinensis Dippel) growing in soil with three levels of P (0, 40 and 80 kg ha-1) and two levels of N (0 and 80 kg ha-1) were exposed to three levels of O3 (ambient - AA, 1.5 x AA, 2.0 x AA) at a free air exposure facility. After one growing season, root biomass, fine root (<2 mm) nutrient concentrations and ratios, and fine root morphology were assessed. Results Nitrogen addition resulted in an up to +100.5% increase in coarse and fine root biomass under AA, and only up to +46.3% increase under 2.0 x AA. Elevated O3 and P addition had a positive effect, while N had a negative effect on P concentrations in fine roots. Nitrogen limitation for root growth expressed as a N:P ratio was more pronounced at elevated O3. Nitrogen addition increased root surface area per soil volume by +78.3% at AA and only by +9.9% at 2.0 x AA. Conclusions Smaller root surface area per soil volume at elevated O3 prevented acquisition of available N, rendering N fertilization of young poplar plantations in such conditions economically and environmentally questionable.
Ključne besede: fine roots, nitrogen, phosphorus, Populusmaximoviczii x berolinensis, ozone, Poplar
Objavljeno v DiRROS: 16.06.2020; Ogledov: 2047; Prenosov: 1131
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