Search results for "callus"
showing 10 items of 63 documents
Physiological and genomic variations in rice cells recovered from direct immersion and storage in liquid nitrogen
1999
The use of cryoprotectants and slow cooling rates are routine procedures for the cryopreservation of plant cell lines. However, our results with rice (Oryza sativa L., cv. Taipei 309) show that calli can be cryopreserved by direct immersion and stored in liquid nitrogen without any cryoprotection. The efficiency of recovery using this method, as well as a conventional method was generally increased with a previous abscisic acid (ABA) treatment. Following cryopreservation, calli demonstrated some differences with respect to unfrozen calli of the same lines. Thus, resistance to freezing stress (−20°C for 2 h) increased significantly in all lines tested, irrespective of their pre-incubation wi…
Anther and pollen grain culture of rice (Oryza sativa L.)
1981
Factors favouring callus proliferation and subsequent regeneration of plants from pollen grains of rice anthers (Oryza sativa L., cvx. Bahia, Girona, Balilla × Sollana and Sequial) were determined. Cultivar differences in response were found, such as a high rate of haploid plant regeneration.
Phenotypic characterization of the progenies of rice plants derived from cryopreserved calli
1999
The progenies of rice plants (Oryza sativa L.) differentiated from calli that had been cryopreserved and from control (non-cryopreserved) calli were used to study the influence of selection pressure during cryopreservation. The phenotypic evaluation of these progenies was based mainly on the response of seedlings and calli to freezing stress and on the characterization of protoplast and cell populations by flow cytometric analyses. The patterns of response to freezing stress, as well as the variations in some morphological and physiological cell parameters, were unrelated to the origin (cryopreserved or control calli) of the parental plants.
Temporomandibular arthropathies : a retrospective study with histopathological characteristics
2018
Background To investigate the incidence of temporomandibular arthropathies diagnosed in a university center and to describe their histopathological characteristics. Material and Methods Temporomandibular arthropathy cases with corresponding slides were selected from an oral and maxillofacial surgical pathology service. Cases of exclusively articular disc disease were not included. Results The mean age was 31.3 years with a predominance of females (69.7%). Of these diagnoses, 53.6% were unilateral condylar hyperplasia, 17.8% were bony ankylosis, 14.3% were degenerative joint disease, 10.7% were osteochondroma, and 3.6% were synovial chondromatosis. Condylar hyperplasia presented as thick fib…
Investigation of the Alkaloid Content of Rauwolfia serpentina Roots from Regenerated Plants.
1991
The indole alkaloid content of RAUWOLFIA SERPENTINA roots from regenerated plants (from stem-and root-callus) was compared with the parental stock. Although the total alkaloid content seems to be slightly higher in the roots from regenerated plants, HPLC-analysis of individual alkaloids indicated that the contents of the alkaloids ajmaline ( 1), serpentine ( 2), and reserpine ( 3) are lower than in the roots of the parental stock. The glucoalkaloid raucaffricine ( 4) was identified as a constituent of all samples, thus providing the first evidence for its occurrence in roots of RAUWOLFIA SERPENTINA.
Morphogenesis and Cardenolide Formation in Digitalis obscura Cultures
1991
Summary Cardenolide formation was investigated in hypocotyl cultures of Digitalis obscura L. established on MS medium with growth regulators selected to promote either callus formation, caulogenesis, embryogenesis or rhizogenesis. Examination of the cardenolide composition of leaves from mature plants was also performed. Several compounds of series A and C were identified by HPLC in in vitro and in vivo grown tissues, no marked differences being found between their cardenolide patterns. RIA determinations showed that shoot- or embryo-forming calli accumulated significantly higher amounts of digoxigenin derivatives than undifferentiated or rhizogenic cultures. In any case, field plants prese…
A relationship between tolerance to dehydration of rice cell lines and ability for ABA synthesis under stress
2005
Plant dehydration is commonly caused by some adverse environmental conditions such as salinity, drought and freezing. As the plant hormone abscisic acid (ABA) is involved in responses to water stress, we studied its putative relationship with the degree of tolerance to these abiotic stresses. For this purpose we used cell lines that had been established from mature embryos of rice (Oryza sativa L, cvs. Bahia and Bomba), and selected by their high (L-T) or low (L-S) levels of tolerance to each type of stress. Tolerance of rice calli to either osmotic, saline, or freezing stress was generally improved by a previous treatment with ABA. This ABA effect was evident in those callus lines with low…
Isolation, culture and plant regeneration from protoplasts of Sideritis angustifolia
1998
Summary Factors promoting high yields of viable protoplasts from leaves of Sideritis angustifolia are reported. Isolated protoplasts divided and gave rise to callus when plated in modified liquid MS medium with growth regulators. Best plating efficiency was obtained when protoplast were cultured in the presence of 6 μM BA and 2 μM NAA. Calli were then transferred onto solidified regeneration media. Adventitious bud differentiation was only observed in calli grown on medium containing 8 μM BA and 2 μM NAA. These buds proliferated quickly when placed on hormone-free medium and subsequendy regenerated new buds and shoots. Once developed shoots were excised, the remaining tissues maintained thi…
Morphogenesis in leaf and single-cell cultures of mature Juniperus oxycedrus
1996
Single cells were mechanically isolated from leaf-derived callus of mature Juniperus oxycedrus L. These cells divided and gave rise to callus when plated on medium containing growth regulators. Best plating efficiency was obtained on a modified Schenk and Hildebrandt medium supplemented with 0.6 micro M 2,4-dichlorophenoxyacetic acid and 100 mg l(-1) casein hydrolyzate. Although single-cell-derived callus showed poor morphogenic potential, both adventitious shoots and embryogenic tissues differentiated from the callus. We also achieved induction of somatic embryogenesis in leaf explants of mature J. oxycedrus trees cultured in the presence of 6.0 or 10.0 micro M 2,4-dichlorophenoxyacetic ac…
Anthraquinones from Ophiorrhiza pumila tissue and cell cultures
1998
We have succeeded in initiating and establishing systems of tissue and cell cultures of Ophiorrhiza pumila. Examination of the constituents of the methanol extract of the cultured calli revealed the presence of 11 anthraquinones including two new ones whose structures have been rigorously proved using advanced spectroscopic methods. These findings demonstrated a remarkable difference in the constituents between the wild plants and the callus tissue or cultured cells; the former is devoid of anthraquinones and contains a variety of camptothecin-related alkaloids whereas the latter contains a significant amount of anthraquinones and shows no indication of the presence of alkaloids after sever…