Response of antioxidative enzymes to long-term Tomato spotted wilt virus infection and virus elimination by meristem-tip culture in two Impatiens species

Ornamental plants Impatiens hawkerii and Impatiens walleriana are susceptible to Tomato spotted wilt virus infection that can be eradicated by meristem-tip propagation. Comparison of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) profiles of healthy, infected and virus-eliminated plants showed that long-term infection did not cause major changes in I. hawkerii, but caused induction of several APX and GPX isoforms, increase in Mn-SOD and APX and a decrease in CAT activity in I. walleriana. This is the first report on the effects of virus elimination by meristem-tip propagation on the antioxidative metabolism in plants. (C) 2012 Elsevier Ltd. All rights reserved.Serbian Ministry of Education and Science [TR-31019

High seed Mn content does not affect germination of in vitro produced Centaurium pulchellum seeds

The effect of high Mn2+ content on Centaurium pulchellum seed germination has been investigated. Seeds containing extremely high Mn2+ content were produced by culturing single-node flowering explants for 2 months in the MS-media, supplemented with Mn in concentrations ranging from 1 to 10,000 mu M. Although the seeds displayed the capacity to accumulate high amount of Mn, their germination was undisturbed. EPR spectroscopy was used to measure the ratio of free (aqueous) Mn to bound Mn and it was found that over 97% of total Mn was in the bound form. With elevating the external Mn supply, seed Mn concentration also increased, but the proportion of free Mn2+ fraction decreased from 3% in the control (1 mu M Mn) to 0.35% and 0.15% in high Mn supply (1000 mu M and 10,000 mu M, respectively). These results suggest that an elevation of internal Mn concentration in seeds is associated with increased Mn binding pools, hence Mn remains bound during germination. Consequently, the action of potentially harmful Mn2+ ions, which may generate ROS and affect seed viability, is alleviated. (C) 2008 Elsevier B.V. All rights reserved.Serbian Ministry of Science and Environmental Protection [143031, 143016, 143020

High seed Mn content does not affect germination of in vitro produced Centaurium pulchellum seeds

The effect of high Mn2+ content on Centaurium pulchellum seed germination has been investigated. Seeds containing extremely high Mn2+ content were produced by culturing single-node flowering explants for 2 months in the MS-media, supplemented with Mn in concentrations ranging from 1 to 10,000 mu M. Although the seeds displayed the capacity to accumulate high amount of Mn, their germination was undisturbed. EPR spectroscopy was used to measure the ratio of free (aqueous) Mn to bound Mn and it was found that over 97% of total Mn was in the bound form. With elevating the external Mn supply, seed Mn concentration also increased, but the proportion of free Mn2+ fraction decreased from 3% in the control (1 mu M Mn) to 0.35% and 0.15% in high Mn supply (1000 mu M and 10,000 mu M, respectively). These results suggest that an elevation of internal Mn concentration in seeds is associated with increased Mn binding pools, hence Mn remains bound during germination. Consequently, the action of potentially harmful Mn2+ ions, which may generate ROS and affect seed viability, is alleviated. (C) 2008 Elsevier B.V. All rights reserved.Serbian Ministry of Science and Environmental Protection [143031, 143016, 143020

Basic seed germination characteristics of the endemic species Nepeta rtanjensis (Lamiaceae)

Nepeta rtanjensis is an endemic plant species that was first recorded in 1974 in the eastern part of Serbia. Because of the small number of discovered specimens and low seed viability, it has been difficult to determine the seed germination characteristics of this species. Using in vitro culture techniques, we obtained sufficient plants for successful reintroduction. In the first year approximately 500 000 seeds were collected and subjected to various seed germination tests. The seeds were positive photoblastic and germination was under the control of the phytochrome pigment system. The requirement for light could be substituted by gibberellins. The seeds were nitrate insensitive, but responded to treatment with liquid smoke.nul

Sucrose effects on in vitro fruiting and seed production of Centaurium pulchellum

The effect of sucrose on fruiting, seed production, and seed germination of lesser centaury [Centaurium pulchellum (Sw.) Druce] was examined using explants of flowers and flower buds. Sucrose concentrations in the culture medium ranged from 0.003 to 0.3 M. It has been shown that the number of auxiliary buds, capsules dimension, number of viable seeds per capsule and seed dimensions increased with the increase of sucrose concentrations. The highest values were recorded at sucrose concentrations higher than 0.03 M, except for seeds size, which were larger at sucrose concentration ranging from 0.003 to 0.1 M. The germination of in vitro produced seeds was affected by previous culture history: a higher germination percentage was obtained in seeds that were raised from explants originally grown on medium with sucrose concentrations higher than 0.003 M.nul

Basic seed germination characteristics of the endemic species Nepeta rtanjensis (Lamiaceae)

Nepeta rtanjensis is an endemic plant species that was first recorded in 1974 in the eastern part of Serbia. Because of the small number of discovered specimens and low seed viability, it has been difficult to determine the seed germination characteristics of this species. Using in vitro culture techniques, we obtained sufficient plants for successful reintroduction. In the first year approximately 500 000 seeds were collected and subjected to various seed germination tests. The seeds were positive photoblastic and germination was under the control of the phytochrome pigment system. The requirement for light could be substituted by gibberellins. The seeds were nitrate insensitive, but responded to treatment with liquid smoke.nul

Stimulation of empress tree seed germination by liquid smoke

The germination of Empress tree (Paulownia tomentosa Steud.) seeds is phytochrome-controlled. Liquid smoke could not induce germination in darkness but red light irradiation of liquid smoke imbibed seeds induced a high percentage of germination. Maximum germination was achieved at liquid smoke concentration of 0.1% (v/v) when present during the imbibition phase or during the phase of phytochrome activity. The light requirement of these seeds could be completely substituted by exogenously applied gibberellins. In the presence of liquid smoke, optimal concentrations of GA(3), GA(4), and GA(9) necessary for inducing germination were several times lower than in the controls, while that of GA(7) was equally active when applied at a concentration one order of magnitude lower. The inhibitory effect of the applied growth retardants was strongly reduced and liquid smoke, in the presence of retardants, allowed light-induced germination, if applied simultaneously or after retardants treatment.nul

Stimulation of empress tree seed germination by liquid smoke

The germination of Empress tree (Paulownia tomentosa Steud.) seeds is phytochrome-controlled. Liquid smoke could not induce germination in darkness but red light irradiation of liquid smoke imbibed seeds induced a high percentage of germination. Maximum germination was achieved at liquid smoke concentration of 0.1% (v/v) when present during the imbibition phase or during the phase of phytochrome activity. The light requirement of these seeds could be completely substituted by exogenously applied gibberellins. In the presence of liquid smoke, optimal concentrations of GA(3), GA(4), and GA(9) necessary for inducing germination were several times lower than in the controls, while that of GA(7) was equally active when applied at a concentration one order of magnitude lower. The inhibitory effect of the applied growth retardants was strongly reduced and liquid smoke, in the presence of retardants, allowed light-induced germination, if applied simultaneously or after retardants treatment.nul

Influence of carbohydrate source on Nepeta rtanjensis growth, morphogenesis, and nepetalactone production in vitro

A wide range of sucrose, fructose, and glucose levels in culture media was tested in vitro in order to determine those that provide optimum growth, morphogenesis, and the production of secondary metabolites in Nepeta rtanjensis Diklic and Milojevic shoots. The effect of different concentrations of the carbohydrates in culture media on the internal carbohydrate status of N. rtanjensis shoots was also determined. Our results show that in vitro growth and development of N. rtanjensis, as well as nepetalactone accumulation, are significantly affected by both the type of carbohydrate and its concentration in the culture medium. Glucose proved to be the most efficient carbon and energy source.nul

Influence of carbohydrate source on Nepeta rtanjensis growth, morphogenesis, and nepetalactone production in vitro

A wide range of sucrose, fructose, and glucose levels in culture media was tested in vitro in order to determine those that provide optimum growth, morphogenesis, and the production of secondary metabolites in Nepeta rtanjensis Diklic and Milojevic shoots. The effect of different concentrations of the carbohydrates in culture media on the internal carbohydrate status of N. rtanjensis shoots was also determined. Our results show that in vitro growth and development of N. rtanjensis, as well as nepetalactone accumulation, are significantly affected by both the type of carbohydrate and its concentration in the culture medium. Glucose proved to be the most efficient carbon and energy source.nul