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Direct differentiation of ears and tassels from cultured shoot apices of maize
Xuehong Li,Juren Zhang
Science China Life Sciences , 1999, DOI: 10.1007/BF02881743
Abstract: In vitro morphogenesis of inflorescences from the cultured corn seedling shoot tips was obtained on modified Murashige and Skoog (MS) medium in complete darkness. Some shoot tip meristems excised from seedlings of inbred line 515, inbred line 8112 and their filial generations would directly give rise to florets on modified MS medium supplemented with 2.0 mg/L N6 -bezyladenine (6-BA) in five or six weeks. On the medium with 1.0 mg/L 6-BA and 0.2 mg/L 2, 4-dichlorophenoxy acetic acid (2,4-D), the explants swelled first, and produced multiple shoot clumps, then the culture of the shoot tips from all of the six inbred lines in experiment would ultimately initiate to develop ears and tassels accompanied by multiple shoot clumps developing on the medium with 1.0 mg/L 6-BA and 0.2 mg/L indole-3-butyric acid (IBA). The developmental patterns of the corn inflorescences were similar to the controls of normal plants in the field, but the number of the ears was much more than that of the tasselsin vitro. It seemed that proper kinds and concentrations of exogenous hormones were necessary for the initiation and development of the inflorescences. The genotype of explants was responsible for the response to culture conditions. It could be inferred that there were different control mechanisms existing in the vegetative and reproductive developmental processes of maize, because the cultured shoot tips could directly produce the reproductive organs.
Direct differentiation of ears and tassels from cultured shoot apices of maize
Li Xuehong,and Juren Zhang,
李学红
,张举仁

中国科学C辑(英文版) , 1999,
Abstract: In vitro morphogenesis of inflorescences from the cultured corn seedling shoot tips was obtained on modified Murashige and Skoog (MS) medium in complete darkness. Some shoot tip meristems excised from seedlings of inbred line 515, inbred line 8112 and their filial generations would directly give rise to florets on modified MS medium supplemented with 2.0 mg/L N6-bezyladenine (6-BA) in five or six weeks. On the medium with 1.0 mg/L 6-BA and 0. 2 mg/L 2, 4-dichlorophenoxy acetic acid (2, 4-D), the explants swelled first, and produced multiple shoot clumps, then the culture of the shoot tips from all of the six inbred lines in experiment would ultimately initiate to develop ears and tassels accompanied by multiple shoot clumps developing on the medium with 1.0 mg/L 6-BA and 0. 2 mg/Lin-dole-3-butyric acid (IBA). The developmental patterns of the corn inflorescences were similar to the controls of normal plants in the field, but the number of the ears was much more than that of the tassels in vitro. It seemed that proper kinds and concentrations of exogenous hormones were necessary for the initiation and development of the inflorescences. The genotype of explants was responsible for the response to culture conditions. It could be inferred that there were different control mechanisms existing in the vegetative and reproductive developmental processes of maize, because the cultured shoot tips could directly produce the reproductive organs.
In vitro Regeneration by Indirect Organogenesis of Selected Kenyan Maize Genotypes using Shoot Apices
J. Muoma,G. Muluvi,J. Machuka
Biotechnology , 2008,
Abstract: The study reports a reliable and reproducible regeneration system of two open pollinated varieties-OPV`s (Katumani KAT and dry land cultivar DLC1), a hybrid (DH01) and an inbred line (TL08) using shoot apices as explants via organogenesis. The shoot apices were cultured on Murashige and Skoog (MS) basal media supplemented with 9 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 8.88, 17.75, 26.64, 35.52 or 44.40 μM N6-benzylaminopurine (BAP) with (+) or without (-) 296 μM adenine for calli induction. The most effective combination for calli induction was modified MS media containing 26.64 μM BAP and 296 μM adenine. Calli was maintained on MS media with 9 μM 2, 4-D and 4.44 μM BAP for calli proliferation. Calli of TL08 genotype directly formed shoots on the media containing 9 μM 2, 4-D and 26.64 μM BAP, while the KAT, DLC1 and DHO1 formed a mixture of embryogenic and organogenic calli on the media supplemented with 9 μM 2, 4-D and 4.44 μM BAP. The frequency of callus formation was genotype dependant with KAT 55%, DLC1 35%, DH01 47% and TL08 44%. The number of shoot formed by the selected varieties ranged from 4.9 to 5.7 shoots depending on the genotypes. The number of shoots formed on the media supplemented with 296 μM adenine was higher than that on media without adenine. Shoots were regenerated from organogenic calli after 4-6 weeks depending on the genotype and the presence or absence of adenine, with plant regeneration varying from between 29-55%. Root induction was promoted using MS media supplemented with 1.97 and 2.95 μM Indole-3-butyric acid (IBA). Seeds from in vitro regenerated plants (R0) produced normal plant (R1) in the field trial and were comparable to the plants grown with the mother seeds.
Gene Transfer by Particle Bombardment of Embryogenic Tissue Derived from Vegetative Shoot Apices of Mature Trees of Pinus roxburghii (Chir Pine)
Ravindra B. Malabadi,K. Nataraja
American Journal of Plant Physiology , 2007,
Abstract: This study for the first time was aimed at developing a protocol for the genetic transformation of embryogenic tissue derived from the vegetative shoot apices of mature trees of P. roxburghii. This was achieved via the introduction of a bar-GUS cassette under the control of the ubiquitin promoter, through biolistic transfer. Expression of positive histochemical GUS activity (31%) in the bombarded embryogenic tissue was observed. PCR analysis of bar transgenes (54%) transformation efficiency indicated successful genetic modifications of P. roxburghii embryogenic tissue by the pAHC25 plasmid. This is the first successful report of genetic transformation in P. roxburghii using embryogenic tissue derived from the mature trees indicating that Chir pine is amenable to gene transfer.
Enhancement of Leaf Gas Exchange and Primary Metabolites under Carbon Dioxide Enrichment Up-Regulates the Production of Secondary Metabolites in Labisia pumila Seedlings  [PDF]
Mohd Hafiz Ibrahim,Hawa Z.E. Jaafar
Molecules , 2011, DOI: 10.3390/molecules16053761
Abstract: A split plot 3 by 3 experiment was designed to investigate and distinguish the relationships among production of primary metabolites (soluble sugar and starch), secondary metabolites (total phenolics, TP; total flavonoids, TF) and leaf gas exchange of three varieties of the Malaysian medicinal herb Labisia pumila Blume, namely the varieties alata, pumila and lanceolata, under three levels of CO2 enrichment (400, 800 and 1,200 μmol mol?1) for 15 weeks. The treatment effects were solely contributed by CO2 enrichment levels; no varietal differences were observed. As CO2 levels increased from 400 to 1,200 μmol mol?1, the production of carbohydrates also increased steadily, especially for starch more than soluble sugar (sucrose). TF and TP content, simultaneously, reached their peaks under 1,200 μmol exposure, followed by 800 and 400 μmol mol?1. Net photosynthesis (A) and quantum efficiency of photosystem II (fv/fm) were also enhanced as CO2 increased from 400 to 1,200 μmol mol?1. Leaf gas exchange characteristics displayed a significant positive relationship with the production of secondary metabolites and carbohydrate contents. The increase in production of TP and TFs were manifested by high C/N ratio and low protein content in L. pumila seedlings, and accompanied by reduction in cholorophyll content that exhibited very significant negative relationships with total soluble sugar, starch and total non structural carbohydrate.
Cultura de apices caulinares de Musa sp. var. Ma??: estabelecimento, micropropaga??o e enraizamento in vitro
Domingues, E.T.;Tulmann Neto, A.;Mendes, B.M.J.;
Scientia Agricola , 1995, DOI: 10.1590/S0103-90161995000200030
Abstract: the response of banana shoot tips var. "ma??", were accessed for different micropropagation conditions such as media composition and explant type. shoot tip apices were extracted in five different ways. shoot tips without immature leaves with 0.7 cm in diameter and 1.0 cm in lenght, tended to produce a larger number of developing buds. the number of buds developed was higher in shoot tips grown in liquid media with agitation than in semi solid media. shoot tips grown in static liquid media had the lowest number of buds developed. the lowest concentration of the growth regulator bap to produce a higher number of buds was 5.0 mg.l-1. for rooting, the best concentration of naa and iba was 0.1 mg.l-1. this concentration rooted plants hi two weeks.
Impact of Elevated Carbon Dioxide on Primary, Secondary Metabolites and Antioxidant Responses of Eleais guineensis Jacq. (Oil Palm) Seedlings  [PDF]
Mohd Hafiz Ibrahim,Hawa Z.E. Jaafar
Molecules , 2012, DOI: 10.3390/molecules17055195
Abstract: A split plot 3 by 3 experiment was designed to investigate the relationships among production of primary metabolites (soluble sugar and starch), secondary metabolites (total flavonoids, TF; total phenolics, TP), phenylalanine lyase (PAL) activity (EC 4.3.1.5), protein and antioxidant activity (FRAP) of three progenies of oil palm seedlings, namely Deli AVROS, Deli Yangambi and Deli URT, under three levels of CO2 enrichment (400, 800 and 1,200 μmol·mol?1) for 15 weeks of exposure. During the study, the treatment effects were solely contributed by CO2 enrichment levels; no progenies and interaction effects were observed. As CO2 levels increased from 400 to 1,200 μmol·mol?1, the production of carbohydrate increased steadily, especially for starch more than soluble sugar. The production of total flavonoids and phenolics contents, were the highest under 1,200 and lowest at 400 μmol·mol?1. It was found that PAL activity was peaked under 1,200 μmol·mol?1 followed by 800 μmol·mol?1 and 400 μmol·mol?1. However, soluble protein was highest under 400 μmol·mol?1 and lowest under 1,200 μmol·mol?1. The sucrose/starch ratio, i.e., the indication of sucrose phosphate synthase actvity (EC 2.4.1.14) was found to be lowest as CO2 concentration increased from 400 > 800 > 1,200 μmol·mol?1. The antioxidant activity, as determined by the ferric reducing/antioxidant potential (FRAP) activity, increased with increasing CO2 levels, and was significantly lower than vitamin C and α-tocopherol but higher than butylated hydroxytoluene (BHT). Correlation analysis revealed that nitrogen has a significant negative correlation with carbohydrate, secondary metabolites and FRAP activity indicating up-regulation of production of carbohydrate, secondary metabolites and antioxidant activity of oil palm seedling under elevated CO2 was due to reduction in nitrogen content in oil palm seedling expose to high CO2 levels.
Effect of cytokinins on shoot apical meristem in Nicotiana tabacum
Uzelac Branka,Jano?evi? Du?ica,Stoji?i? Dragana,Budimir Sne?ana
Archives of Biological Sciences , 2012, DOI: 10.2298/abs1202511u
Abstract: Cytokinins are involved in plant cell proliferation leading to plant growth and morphogenesis. The size, activity and maintenance of the shoot apical meristem (SAM) are defined by a balanced rate of mitotic cell divisions and functional cell differentiation that are controlled by cytokinins. In order to investigate the effect of exogenous cytokinin on SAM, morpho-anatomical changes in the shoot apices of tobacco treated with benzyladenine (BA) were compared to those of untreated control plants.
Measurement of Open Apices in Teeth for Estimation of Age In Children  [PDF]
Ashish Shrestha,R P Yadav,S Shrtestha,I K Majarjan,S Camelio
Health Renaissance , 2014, DOI: 10.3126/hren.v12i1.11983
Abstract: Background: Estimation of age has been a major factor in identification of an individual, either living or after death. Objective: To estimate and assess the dental age of children by measuring the open apices of the teeth using panoramic radiograph applying linear regression equation. ? Methods: This was a retrospective cross-sectional study conducted on 50 children (25 boys and 25 girls) aged between 5-15 years. The seven left permanent mandibular teeth were assessed using panoramic radiographs which were collected from Medical Record Department, Manipal University, taken during the course of diagnosis and treatment. The number of teeth with closed apical and with open apical end of roots were examined and measured. The values were tabulated and placed on the linear regression equation proposed by Cameriere et al for the estimation of dental age. Result: The result showed no significant difference between the dental age (10.13±1.69 years) and the chronological age (10.31±1.75 years) (p=0.26). The method underestimated the mean age by 0.11 years and 0.23 years for the boys and girls, respectively. The paired sample t- test showed no significant difference between dental age and chronological age for boys (p=0.546) as well as for girls (p=0.351) Conclusion: The estimated age of children by measuring the open apices of the teeth using panoramic radiograph linear regression equation used in the European subjects closely matches with the chronological age in Asian subjects also. Keeping in context to validate more accurately the significance of linear regression equation, there is a need of larger sample size belonging to variety of ethnic and socioeconomic background. DOI: http://dx.doi.org/10.3126/hren.v12i1.11983 Health Renaissance 2014;12(1):33-37
Development of a genotype independent and transformation amenable regeneration system from shoot apex in rice (Oryza sativa spp. indica) using TDZ
Mohitosh Dey,Souvika Bakshi,Gabor Galiba,Lingaraj Sahoo,Sanjib Kumar Panda
3 Biotech , 2012, DOI: 10.1007/s13205-012-0051-y
Abstract: Agrobacterium-mediated transformation of indica rice has been established in only a limited number of cultivars because the regeneration of plants from transformed embryogenic calli is highly cultivar-specific. Establishment of a highly efficient plant regeneration system from shoot apex explants applicable to many cultivars of indica rice will accelerate the application of transformation technology in breeding programs and functional genomics study. We established an efficient shoot multiplication and plant regeneration system from shoot apices of indica rice using thidiazuron (TDZ) as a plant growth regulator. Shoot apices cultured on MS basal medium devoid of plant growth regulators formed solitary shoots in 90% of cultures. Addition of TDZ or benzylaminopurine to regeneration medium significantly influenced formation of multiple shoots directly from shoot apex explants without an intervening callus stage. Best shoot proliferation response (10.3 shoots per explant) was recorded when shoot apices were cultured on media supplemented with 4 mg/l TDZ. No synergistic effect on shoot proliferation was observed when indole-3-acetic acid and indole-3-butyric acid were supplemented to media containing 4 mg/l TDZ. The regeneration system was efficient in evoking multiple shoot proliferation in eight different cultivars of indica rice. Shoots were rooted in MS basal medium and plantlets were acclimatized with 100% survival rate. The shoot apex explants of all the eight cultivars of indica rice were found competent to Agrobacterium-mediated transformation while explants from IR-64 showed highest transient GUS expression. This variety-independent transformation amenable regeneration system from shoot apices may widely be applicable for genetic transformation of indica varieties.
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