http://www.ejbiotechnology.info/index.php/ejbiotechnology/article/viewFile/v12n2-1/704

AgNO3 - a potential regulator of ethylene activity and plant growth modulator

Synseed technology-a complete synthesis.

Somatic embryogenesis is a developmental process where a plant somatic cell can dedifferentiate to a totipotent embryonic stem cell that has the ability to give rise to an embryo under appropriate conditions. This new embryo can further develop into a whole plant. In woody plants, somatic embryogenesis plays a critical role in clonal propagation and is a powerful tool for synthetic seed production, germplasm conservation, and cryopreservation. A key step in somatic embryogenesis is the transition of cell fate from a somatic cell to embryo cell. Although somatic embryogenesis has already been widely used in a number of woody species, propagating adult woody plants remains difficult. In this review, we focus on molecular mechanisms of somatic embryogenesis and its practical applications in economic woody plants. Furthermore, we propose a strategy to improve the process of somatic embryogenesis using molecular means.

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Application of Somatic Embryogenesis in Woody Plants.

Cryopreservation is a perfect method for long-term conservation of plant genetic resources, using very low temperature (liquid nitrogen, -196 C). This method has been recognized as a practical and efficient tool for the long-term storage of germplasm. Cryopreservation methods may provide the conditions for unlimited conservation of biological materials by reducing metabolic rates. During the cryopreservation all biochemical activities significantly reduced and biological deterioration are stopped. Conservation and subsequent sustainable use of genetic resources are essential to meet the demand for future food security. Several techniques have been developed yet to minimize the damaging effects of desiccation and freezing, ensuring high recovery of plant materials. Cellular division of germplasm is normally repressed after exposure to LN. In addition, metabolic and most physical processes are stopped at this temperature. Thus, plants can be stored for very long time and the problems such as genetic instability and the risk of loose accessions due to contamination or human error during subculture overcome. Techniques like cryopreservation collect and conserve plant genetic resources, especially plants with limited seed storage capability. There is only limited number of plants that cryopreservation techniques are used for their germplasm conservation, mainly because the techniques need to be adapted for each species. Therefore, continued efforts are needed in cryopreservation techniques to develop protocols for a wider range of plants. Formation of ice crystal during cryopreservation is detrimental to cellular structure integrity and causes physical damage to the cells. Air-drying, freeze dehydration, osmotic dehydration, addition of penetrating and non-penetrating cryoprotective substances, and hardening metabolism or combinations of these processes are cryogenic strategies. Nowadays, conservation of plant germplasm has altered from slow cooling to vitrification. However, the availability or developments of simple, reliable and cost-effective strategies and the subsequent regeneration of the plants are basic requirements for germplasm conservation.

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Conservation of plant genetic resources by cryopreservation.

Tomorrow’s forests face extreme pressures from contemporary climate change, invasive pests, and anthropogenic demands for other land uses. These pressures, collectively, demand land managers to reassess current and potential forest management practices. We discuss three considerations, functional restoration, assisted migration, and bioengineering, which are currently being debated in the literature and have the potential to be applied independently or concurrently across a variety of scales. The emphasis of functional restoration is to reestablish or maintain functions provided by the forest ecosystem, such as water quality, wildlife habitat, or carbon sequestration. Maintaining function may call upon actions such as assisted migration—moving tree populations within a species current range to aid adaptation to climate change or moving a species far outside its current range to avoid extinction—and we attempt to synthesize an array of assisted migration terminology. In addition, maintenance of species and the functions they provide may also require new technologies, such as genetic engineering, which, compared with traditional approaches to breeding for pest resistance, may be accomplished more rapidly to meet and overcome the challenges of invasive insect and disease pests. As managers develop holistic adaptive strategies to current and future anthropogenic stresses, functional restoration, assisted migration, and bioengineering, either separately or in combinations, deserve consideration, but must be addressed within the context of the restoration goal.

/pdf/considerations-for-restoring-temperate-forests-of-tomorrow-4ozt7glpmh.pdf

Considerations for restoring temperate forests of tomorrow: forest restoration, assisted migration, and bioengineering

Potential applications of cryogenic technologies to plant genetic improvement and pathogen eradication.

Abstract The effect of silver nitrate on shoot differentiation and shoot growth was examined in order to improve the regeneration efficiency of pistachio (Pistacia vera L. cv. Kirmizi) in vitro. Nodal explants of in vitro-grown seedlings were used to test various concentrations and combinations of 6-benzyladenine (BA), kinetin (KIN), gibberellic acid (GA3) and silver nitrate (AgNO3). Addition of AgNO3 up to 48.0 μM to the culture medium improved the regeneration frequency and shoot growth, and reduced basal callus formation in all regenerated explants. The highest regeneration frequency (100%) was recorded on Murashige and Skoog (MS) medium containing 9.0 μM BA, 0.2 μM GA3 and 24.0 or 48.0 μM AgNO3 in combination. The best proliferation response in terms of both shoot formation and low callus production was obtained in the medium containing a combination of 9.0 μM BA, 0.2 μM GA3 and 12.0 μM AgNO3. Regenerated shoots, coming from three cycles of subculturing in proliferation media, were rooted in half-strength MS medium containing 12.0 μM indole-3-butyric acid (IBA). Well rooted plantlets were acclimatized and eventually established in peat and perlite. The development and optimization of an effective micropropagation protocol that is presented in this paper can give an important contribution to improve the quality of pistachio plants and, as a consequence, of orchard production in Middle East countries.

In vitro response of pistachio nodal explants to silver nitrate. Sci Hortic

In vitro response of pistachio nodal explants to silver nitrate

An efficient in vitro propagation protocol, applicable both to young and mature explants of two Thymus spp., results in genetically stable plantlets. In vitro-grown shoot tips of Thymus vulgaris L. were exposed to cytokinins (6-benzyladenine, kinetin, and thidiazuron) alone or in combination with auxins, gibberellic acid (GA3) and/or silver nitrate in order to optimize in vitro shoot proliferation. Optimum shoot proliferation (97% regeneration rate, with 8.6 shoots produced per explant) was obtained when semi-solid Murashige and Skoog (MS) medium was supplemented with 1 mg L−1 kinetin and 0.3 mg L−1 GA3. Rooting of the shoots was easily obtained on semi-solid MS medium that was either hormone-free or supplemented with auxins. However, the best root apparatus (92.5% rooting rate, with 19 adventitious roots per shoot) developed on MS medium supplemented with 0.05 mg L−1 2,4-dichlorophenoxyacetic acid. Genetic stability was confirmed in the in vitro-germinated mother plant as well as the shoots that underwent two, four, six, eight, or ten cycles of in vitro subculturing by random amplified polymorphic DNA (RAPD) analysis. When applied to the micropropagation of mature shoot tips of T. longicaulis C. Presl subsp. longicaulis var. subisophyllus (Borbas) Jalas, the optimized in vitro propagation protocol resulted in a 97.5% shoot regeneration rate, with five shoots formed per explant, and 100% rooting. Rooted plantlets of both species were transferred to 250-mL plastic pots and successfully acclimatized by gradually reducing the relative humidity.

In vitro propagation from young and mature explants of thyme (Thymus vulgaris and T. longicaulis) resulting in genetically stable shoots

AM symbiosis did not strongly affect
 Arundo donax
 performances under salt stress, although differences in the plants inoculated with two different fungi were recorded.
 The mechanisms at the basis of the improved tolerance to abiotic stresses by arbuscular mycorrhizal (AM) fungi have been investigated mainly focusing on food crops. In this work, the potential impact of AM symbiosis on the performance of a bioenergy crop, Arundo donax, under saline conditions was considered. Specifically, we tried to understand whether AM symbiosis helps this fast-growing plant, often widespread in marginal soils, withstand salt. A combined approach, involving eco-physiological, morphometric and biochemical measurements, was used and the effects of two different AM fungal species (Funneliformis mosseae and Rhizophagus irregularis) were compared. Results indicate that potted A. donax plants do not suffer permanent damage induced by salt stress, but photosynthesis and growth are considerably reduced. Since A. donax is a high-yield biomass crop, reduction of biomass might be a serious agronomical problem in saline conditions. At least under the presently experienced growth conditions, and plant–AM combinations, the negative effect of salt on plant performance was not rescued by AM fungal colonization. However, some changes in plant metabolisms were observed following AM-inoculation, including a significant increase in proline accumulation and a trend toward higher isoprene emission and higher H2O2, especially in plants colonized by R. irregularis. This suggests that AM fungal symbiosis influences plant metabolism, and plant–AM fungus combination is an important factor for improving plant performance and productivity, in presence or absence of stress conditions.

Elif Aylin Ozudogru

Papers

Potential applications of cryogenic technologies to plant genetic improvement and pathogen eradication.

In vitro response of pistachio nodal explants to silver nitrate. Sci Hortic

In vitro response of pistachio nodal explants to silver nitrate

In vitro propagation from young and mature explants of thyme (Thymus vulgaris and T. longicaulis) resulting in genetically stable shoots

Impact of two arbuscular mycorrhizal fungi on Arundo donax L. response to salt stress.