6 research outputs found
The Response of Picea abies Somatic Embryos to UV-B Radiation Depends on the Phase of Maturation
Ultraviolet-B (UV-B) radiation is a key environmental signal which initiates diverse responses that affect the metabolism, development, and viability of plants. In keeping with our previous studies, we concentrated primarily on how UV-B radiation affects Norway spruce [Picea abies (L.) Karst.] somatic embryo maturation and how phenolics and polyamines (PAs) are linked to the defense response invoked by UV-B irradiation. We treated clusters of Norway spruce embryogenic culture (EC) with UV-B during the five stages of embryo maturation (early, cylindrical, precotyledonary, cotyledonary, and mature embryos). For the first time, we take an advantage of the unique environmental scanning electron microscope AQUASEM II to characterize somatic embryos in their native state. The severity of the irradiation effect on embryonal cell viability was shown to be dependent on the intensity of radiation as well as the stage of embryo development, and might be related to the formation of protoderm. The response of early embryos was characterized by an increase in malondialdehyde (MDA), a marked decrease in PA contents and a decline in phenolics. The reduced ability to activate the defense system seems to be responsible not only for the severe cell damage and decrease in viability but also for the inhibition of embryo development. The significant reduction in spermidine (Spd), which has been reported to be crucial for the somatic embryo development of several coniferous species, may be causally linked to the limited development of embryos. The pronounced decrease in cell wall-bound ferulic acid might correspond to failure of somatic embryos to reach more advanced stages of development. Embryos at later stages of development showed stress defense responses that were more efficient against UV-B exposure
The humidity level matters during the desiccation of Norway spruce somatic embryos
In Norway spruce, as in many other conifers, the germination capacity of somatic embryos is strongly influenced by the desiccation phase inserted after maturation. The intensity of drying during desiccation eminently affected the formation of emblings (i.e., seedlings developed from somatic embryos). Compared to non-desiccated embryos, the germination capacity of embryos desiccated at 100% relative humidity was about three times higher, but the reduction of relative humidity to 95 and 90% had a negative effect on the subsequent embryo development. The water loss observed in these embryos did not lead to an increase in lipid peroxidation, as shown by malondialdehyde levels. Another metabolic pathway in plants that mediates a response to abiotic stresses is directed toward the biosynthesis of polyamines (PAs). The activities of PA biosynthetic enzymes increased steadily in embryos during desiccation at 100% relative humidity, whereas they decreased at lower humidity. The total content of free PAs in the embryos gradually decreased throughout desiccation. The increase in free putrescine (Put) and perchloric acid-insoluble Put conjugates was observed in embryos desiccated at lower humidity. These changes were accompanied to some extent by the transcription of the genes for the PA biosynthesis enzymes. Desiccation at 100% relative humidity increased the activity of the cell wall-modifying enzymes β-1,3-glucanases and chitinases; the activities of these enzymes were also significantly suppressed at reduced humidity. The same pattern was observed in the transcription of some β-1,3-glucanase and chitinase genes. Desiccation treatments triggered metabolic processes that responded to water availability, suggesting an active response of the embryo to the reduction in humidity. A positive effect was demonstrated only for desiccation at high relative humidity. Some of the physiological characteristics described can be used as markers of inappropriate relative humidity during somatic embryo desiccation
Study of polyamine metabolism in cell division and their role in physiological plant processes
3. AIMS To study the role of PA biosynthesis,oxidation and conjugation in maintenanceof free intracellular PA levelsduring the growth and cell cycle of tobacco BY-2 cell culture (Nicotiana tabacum L.cv. Bright Yellow-2). Partial aims: o To describe alterations in the levels of free PA and PA conjugated with HCA during the growth and cell cycle oftobaccoBY-2 cell culture. o To charaďerjzechangesin the activities of PA bioqynthetic en4/mes(ADC, ODC and SAMDC) during the growth and cell cycle oftobacco BY-2 cell culture. o To detenrrinatechangesin the activiý of PA degradation en4fme (DAO) duringthegrowthandcell cycle of tobacco BY-2 cell culture. Following (next)aims: o To evaluatealterationsin the levels of intracellular free and conjugatedPA in tobacco BY-2 cell culture under Cd2*- inducedoxidativestress. o To studythemechanismsof PA homeostasis(biosynthesis, degradation and conjugation) during the diurnal cycle oftobacco plant(Nicotiana tabacumL. cv. Wisconsin 38). o To evaluate the role of excreted PA in PA homeostasis dwing the growth cycle of tobacco BY-2 and alfalfa (MedicagosativaL.) cell suspensionculture. o To comparechangesin the PA metabolismduring somatic and zygotic embryodevelopmentof Norway spruce(Picea abiesL. (Kars|). 73.cÍLE Studium meÚabolismu po|yaminův pnůběhurůstovéhoa buněčného cyklu tabákové suspenzní ku|tury BY.2 (Nicotiana tabacum L. cv. Bright Yellow-2): určenípodilu biosynÚéry,degradacea konjugacena udrženíhomeostáze polyaminů. Dílčícíle: o Sledoviínízrrěn endogenníchhladin vo|ných a konjugovaných forempolyaminův průběhurůstovéhoa buněenéhocgtuLu.etove suspenzníkulturyBY-2. o Stanoveníaktivit biosyntetictcýchenzymůpolyaminů- ornithin-, arginin- a S-adenosylrnethionindekarboxylrázyv průběhurustového a buněčnéhocyklu tabákovésuspenzríkultury BÝ-2. o Stanovení aktiviý degradačního enzymu polyaminů ďaminoxidázy vprůběhurůstovéhoa buněčnéhocykiu tabrákové suspenztíkultury BY-2. Da|šícile: o Slďoviírrí zrrrěn endogenníchhladin volných a konjugovaných forem polyaminů u tabákové suspenzrí ku'ň'' BY.2 v podmínkáchabiotickéhostresu. . 9to9i.'- regulačních mechanismů homeostiíze polyaminů (tj.biosyntézy,degradacea konjugace)u rostlin tabákuiNícotiana tabacumL.) vprůběhudiumálníhocyklu. o Stanovenípodíluexkrecepolyaminůdo živnéhomédiau tabrákové suspenzníkultury BY-2 a u kultury vojtěšky(Medicago sativa) na udrženíhomeostázepolyarninů. o Sledoviíní zněn endogenních hladin polyarrrinů vpruběhu zygotickéa somatickéembryogenezesmrku-ztepilého(Picea abies L. (Karst.).Department of Experimental Plant BiologyKatedra experimentální biologie rostlinFaculty of SciencePřírodovědecká fakult
Study of polyamine metabolism in cell division and their role in physiological plant processes
3. AIMS To study the role of PA biosynthesis,oxidation and conjugation in maintenanceof free intracellular PA levelsduring the growth and cell cycle of tobacco BY-2 cell culture (Nicotiana tabacum L.cv. Bright Yellow-2). Partial aims: o To describe alterations in the levels of free PA and PA conjugated with HCA during the growth and cell cycle oftobaccoBY-2 cell culture. o To charaďerjzechangesin the activities of PA bioqynthetic en4/mes(ADC, ODC and SAMDC) during the growth and cell cycle oftobacco BY-2 cell culture. o To detenrrinatechangesin the activiý of PA degradation en4fme (DAO) duringthegrowthandcell cycle of tobacco BY-2 cell culture. Following (next)aims: o To evaluatealterationsin the levels of intracellular free and conjugatedPA in tobacco BY-2 cell culture under Cd2*- inducedoxidativestress. o To studythemechanismsof PA homeostasis(biosynthesis, degradation and conjugation) during the diurnal cycle oftobacco plant(Nicotiana tabacumL. cv. Wisconsin 38). o To evaluate the role of excreted PA in PA homeostasis dwing the growth cycle of tobacco BY-2 and alfalfa (MedicagosativaL.) cell suspensionculture. o To comparechangesin the PA metabolismduring somatic and zygotic embryodevelopmentof Norway spruce(Picea abiesL. (Kars|).
Excretion of polyamines in alfalfa and tobacco suspension-cultured cells and its possible role in maintenance of intracellular polyamine contents
Abstract Changes in polyamines (PAs) in cells and cultivation media of alfalfa (Medicago sativa L.) and tobacco bright yellow 2 (BY-2) (Nicotiana tabacum L.) cell suspension cultures were studied ove