Yaser Dewir

Kafrelsheikh University, Horticulture, Faculty Member

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I'm a professor at Kafrelsheikh Univ., Egypt and currently at King Saud Univ. I received my MSc from South China Agricultural Univ. (SCAU) 华南农业大学, China and PhD from Chungbuk National Univ.(CBNU) 충북대학교, Korea. I carried out Postdoc. studies in CBNU, Korea and Univ., of KwaZulu-Natal (UKZN) ,South Africa. My research interests including plant physiology, tissue culture and biotechnology. Contact e-mail: [email protected]
Address: https://www.researchgate.net/profile/Yaser_Dewir

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Flowering of Euphorbia millii Plantlets In Vitro as Affected by Paclobutrazol, Light Emitting Diodes (LEDs) and Sucrose

Acta Horticulturae, 2007

Nutrient utilization during in vitro flowering of Spathiphyllum (Poster presentation)

Biochemical and Physiological Aspects of Hyperhydricity in Liquid Culture System

ABSTRACT Large-scale liquid cultures and automation have proven the potential to resolve manual h... more ABSTRACT Large-scale liquid cultures and automation have proven the potential to resolve manual handling of in vitro cultures at various stages and decreases production cost. However, hyperhydricity is a major problem during in vitro culture of many crops in liquid culture systems. The environment inside culture vessel normally used in plant micropropagation is characterized by high humidity, limited gaseous exchange between the internal atmosphere of the culture vessel and its surrounding environment, and the accumulation of ethylene, conditions that may induce physiological disorders. Hyperhydricity is a disorder of tissue-cultured plants where leaves become translucent and stems swollen, distorted and brittle. Although numerous hypotheses have been put forward to explain hyperhydricity but there is still a lack of knowledge about the nature of signals responsible for hyperhydricity and the metabolic processes which are affected by its development. The concept of stress in relation to hyperhydricity is not completely established. Therefore, it remains difficult to assume that hyperhydric tissues are stressed. Previous studies argued that abnormal morphology observed in hyperhydricity could be attributed to changes occurring at cellular level due to the modifications of membrane composition or DNA content. In order to understand stress and morphological responses in hyperhydric tissues, in the present article, we are reviewing different biochemical and physiological mechanisms of hyperhydricity in several plant species.

Effect of Light-Emitting Diode on Growth and Shoot Proliferation of Euphorbia millii and Spathiphyllum cannifolium

Horticulture Environment and Biotechnology, 2005

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埃及古代农业的历史

Physiological responses of suspension-cultured Carnation cells to gamma rays irradiation and high temperature stress 辐射和高温胁迫康乃馨悬浮培养细胞生长的影响

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Flowering of Euphorbia Millii Plantlets in Vitro as Affected by Paclobutrazol, Light Emitting Diodes (Leds) and Sucrose

Acta Horticulturae, 2007

In Vitro Flowering of Spathiphyllum Cannifolium: Influences of Gibberellic Acid, Culture Type and Sucrose Concentration

Acta Horticulturae, 2006

ABSTRACT

Factors affecting ex vitro rooting and growth of Spathiphyllum plantlets in the microponic culture system

Wonye kwahak kisulchi = Korean journal of horticultural science and technology /

In vitro flowering of Sathiphyllum cannifolium: Influences of gibberellic acid, culture type and sucrose concentration

Ornamental Euphorbia and Spathiphyllum: Application of Bioreactor System and Microponics for Large-scale Production, In vitro Flowering and its Physiology

ABSTRACT

Hyperhydricity: stress related phenomenon?

Wonye kwahak kisulchi = Korean journal of horticultural science and technology /

Weight loss and antioxidants degradation in spears of five asparagus cultivars during cold and freeze storage

Australian Journal of Crop Science

Asparagus (Asparagus officinalis L) is considered as a vegetable rich in antioxidants. The presen... more Asparagus (Asparagus officinalis L) is considered as a vegetable rich in antioxidants. The present study investigated and compared the weight loss and degradation of antioxidants including ascorbic acid (ASC), glutathione (GSH) and cysteine (CYS) in spears of five asparagus cultivars (Bonlim, Eposs, Mars, Thielim and Vulkan). Spears were stored either under cold storage at 4 °C for 12 days or were deep frozen at - 20 °C for 12 months. The results showed that there are significant differences among asparagus cultivars with respect to their weight loss and antioxidants content of ASC, GSH and CYS. Weight loss and degradation of antioxidants were increased with increasing storage duration. At the end of 12 days period of cold storage, the cultivar Eposs showed the highest weight loss with 3.14%, while for the cultivar Vulkan, the lowest weight loss with 2.14% was recorded. When spears were deep frozen, the weight loss was lower than that recorded under cold storage. After 6 months of s...

format_quoteWeight loss and antioxidant degradation varied across cultivars; Vulkan had highest loss under both cold storage and deep freezing.format_quote

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Hyperhydricity in African violet (Saintpaulia ionantha H. Wendl) – biochemical aspects of normal versus hyperhydric shoots regenerated via direct adventitious shoots formation

PROPAGATION OF ORNAMENTAL PLANTS

African violet (Saintpaulia ionantha H. Wendl) is one of the most easily and commonly tissue-cult... more African violet (Saintpaulia ionantha H. Wendl) is one of the most easily and commonly tissue-cultured ornamental plants. Despite this, there are limited reports on the direct adventitious shoots from any organ, most papers reporting on an indirect route through callus. In this study, adventitious shoots were induced directly from leaf and petiole explants from in vitro plantlets derived from shoot tip culture. Murashige and Skoog (MS) medium supplemented with 0.2 mg l-1 6-benzyladenine and 0.1 mg l-1 kinetin resulted in 91.65% direct shoot formation from leaf explants and 70% from petiole explants while 32.5 and 17.5 shoots formed per leaf and petiole explant, respectively. The origin of shoots was histologically demonstrated. The potential role of antioxidant enzymes in protecting hyperhydric plantlets from oxidative injury was examined by analyzing antioxidant enzyme activities of hyperhydric and normal tissues. Activities of catalase (CAT), peroxidase (POD), polyphenol oxidase (P...

Biochemical and Physiological Aspects of Hyperhydricity in Liquid Culture System

Production of Biomass and Bioactive Compounds Using Bioreactor Technology, 2014

Influences of explant type and enzyme incubation on isolated protoplast density and viability in two garlic cultivars

The present study reports on optimizing protoplast isolation and fusion in two garlic cultivars '... more The present study reports on optimizing protoplast isolation and fusion in two garlic cultivars 'Balady' and 'Seds 40'. Protoplast density and viability were investigated in four different explants (etiolated and green parts of the pseudostem and lower and upper parts of the leaves) under enzyme incubation for 1, 2, 3 and 4 h. Among different explants, used for protoplast isolation in Balady cultivar, the upper and lower parts of the leaves produced the highest number of total protoplasts (70 and 66 pps/0.1 ml) at 4 and 3 h enzyme incubation, respectively. However, the etiolated part of pseudostem produced the highest number of viable protoplast in which 52.5 pps/0.1 ml were obtained at 3 h enzyme incubation. For protoplast isolation in Seds 40 cultivar, the highest number of total protoplasts (125 and 107.5 pps/0.1 ml) as well as viable protoplasts (105 and 107.5 pps/0.1 ml) was obtained from the etiolated and the green parts of pseudostem, respectively. The cultivar 'Seds 40' yielded higher total and viable protoplasts than Balady cultivar. Isolated protoplasts of 'Seds 40' and 'Balady' were fused successfully at a protoplast density of 1 × 10 5 using either physical and/or electrical method. Optimization of the source of plant material as well as protoplast isolation conditions for garlic is a crucial step towards a successful protoplast fusion and subsequent colony formation.

format_quoteProtoplast density and viability were assessed using a double chamber haemocytometer; viability quantified by fluorescein diacetate.format_quote

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In vitro propagation and preliminary results of Agrobacterium-mediated genetic transformation of Cordyline fruticosa

South African Journal of Botany, 2015

A method for in vitro propagation through axillary shoot proliferation and induction of adventiti... more A method for in vitro propagation through axillary shoot proliferation and induction of adventitious shoots as well as Agrobacterium-mediated transformation of Cordyline fruticosa is presented. In vitro Cordyline shoots were cultured on MS medium supplemented 0-4 mg l −1 thidiazuron (TDZ) for their multiplication. MS medium supplemented with 0.1 mg l −1 TDZ proved to be the most effective in which 14 shoots per explants were obtained. Leaf segments were excised from in vitro axillary shoots and cultured on MS medium supplemented with TDZ (0-5 mg l −1 ) for callus induction. Following induction, the non-embryogenic calluses were proliferated on MS medium without plant growth regulators. A rapid and efficient method for producing transgenic plants has been developed for Cordyline via Agrobacterium-mediated transformation. Leaf segments from in vitro shoots were co-cultivated with Agrobacterium tumefaciens EHA105, which harbored the binary vector carrying the bar and β-glucuronidase (GUS) genes in the T-DNA region. The results showed that the number of plants expressing GUS gene first increased with inoculation time and bacterial density (OD 600 ), and then dramatically decreased with the increment of both factors. The highest percentage of transformation efficiency (85%) was obtained when the leaf segment explants were inoculated with Agrobacterium for up to 40 min at OD 600 of 1.0 followed by 80 and 75% at OD 600 of 0.8 and 1.2, respectively. The transgenes were confirmed in transgenic plants using GUS primers and gave the expected band size of 750 bp. The results suggested that infection time and Agrobacterium density could have some effects on the transformation efficiency. Southern blot analysis was used for definitive confirmation of tDNA integration in Cordyline and confirmed the results of histochemical GUS assay and PCR amplifications. Regenerated plantlets were acclimatized in greenhouse.

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Effect of photosynthetic photon flux density on growth, photosynthetic competence and antioxidant enzymes activity during ex vitro acclimatization of Dieffenbachia cultivars

The effects of 35, 70 and 100 lmol m-2 s-1 photosynthetic photon flux density (PPFD) were investi... more The effects of 35, 70 and 100 lmol m-2 s-1 photosynthetic photon flux density (PPFD) were investigated on ex vitro acclimatization of micropropagated Dief-fenbachia plants. Various growth characteristics, photosynthetic parameters and activities of antioxidant enzymes and dehydrins (DHN) were investigated. Fresh and dry plant biomass, plant height and root length were highest under the highest PPFD (100 lmol m-2 s-1), but this treatment was responsible for a reduction in the number of leaves. Chlorophyll and carotenoid contents and net photo-synthesis were also optimal in plants grown under the highest irradiance. Stomatal resistance, transpiration rate and F v /F m values decreased with the incremental light irradi-ance. Activities of the antioxidant enzymes superoxide dis-mutase, catalase and glutathione peroxidase were higher in the plants treated with 70 and 100 lmol m-2 s-1 PPFD. Accumulation of 55 kDa, 40 and 22 kDa DHN was observed in all light treatments. These results depict that lower PPFD (35 lmol m-2 s-1) was suitable for acclima-tization of Dieffenbachia plants. High PPFD ([70 lmol m-2 s-1) induced accumulation of antioxidants and accumulation of DHN in the plants which reveals enhanced stress levels.

format_quoteOptimal biomass was achieved at 100 lmol m -2 s -1 for 'Camille' and 'Green Magic', while 'Vesuvius' thrived at 70 lmol m -2 s -1 PPFD.format_quote

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Antifungal activity of some plant extracts against sugar beet damping-off caused by Sclerotium rolfsii

Your article is protected by copyright and all rights are held exclusively by Springer-Verlag and... more Your article is protected by copyright and all rights are held exclusively by Springer-Verlag and the University of Milan. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication.

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Molecular identification of phytoplasmas in fasciated cacti and succulent species and associated hormonal perturbation

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Yaser Dewir

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