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901.
Embryogenic callus (translucent callus) was produced from immature zygotic embryos of Picea wilsonii Mast. Subsequently somatic embryogenesis occurred on the brown callus. The somatic embryos could be stimulated to developinto plantlets on the medium without hormone. Young somatic embryos were produced from embryogenic callus in liquid suspension culture, in which suspensor was several or more than ten times the size of the somatic embryo. The somatic embryo showed very similar to zygotic embryos in micro-section and living material. 相似文献
902.
The somatic embryogenesis was established from mature dehulled seeds. The histological research showed that embryogenic calli were initiated first from absorbed cells of scutellum of mature seed. And then the embryoids derived from the surface of embryogenic callus. Having been the same structure like a zygotic embryo of rice, the embryoids possessed the major parts of scutellum, coleoptile and coleorhiza. In an embryoid, several developmental stages of pro-embryoid, including single embryogenic cells, two, four and multiple cell stage pro-embryeids and some abnormal embryoids were observed. It could be concluded from this experiment that the embryoid from somatic cell culture in Indica rice possessed an original form of a plant in structure like a zygotic did and derived from a single cell. 相似文献
903.
904.
Pascale Gueirard Karine Le Blay Alain Le Coustumier Richard Chaby Nicole Guiso 《FEMS microbiology letters》1998,162(2):331-337
We previously reported the case of a human chronic Bordetella bronchiseptica respiratory infection, due to contact with infected rabbits. Lipopolysaccharides of the human isolates, of one rabbit isolate and of isolates from other origins were analyzed with sera from infected mice, rabbit and human. Antigenicity and length of the lipopolysaccharide molecules varied between isolates. We showed a progressive loss of O-chain during infection, associated with an enhanced susceptibility of the isolates to the bactericidal effect of normal serum. This observation suggests the existence of an intracellular niche which selects for strains with distinct lipopolysaccharide types. 相似文献
905.
907.
By means of co-culture in growth regulator-free medium we analysed whether factors secreted into the medium of Daucus carota (carrot) somatic embryo cultures would be able to overcome the developmental arrest of globular Arabidopsis thaliana somatic embryos. Instead of Arabidopsis embryogenesis being promoted the development of carrot somatic embryos was inhibited at the globular stage in the presence
of Arabidopsis suspension culture aggregates with attached globular embryos. Several experiments showed that this was due to the release
of previously accumulated 2,4-D by the Arabidopsis cultures. (1) In addition to arresting carrot embryogenesis, co-culture with Arabidopsis cell suspensions also induced callus formation on Arabidopsis root segments. (2) Both effects only occurred with Arabidopsis suspensions grown in the presence of 2,4-D and not with those grown in the presence of NAA, demonstrating that Arabidopsis is not segregating a “general” inhibiting factor. (3) Both effects could be prevented by either binding 2,4-D to active charcoal
or by washing it away by changing the medium daily. (4) Uptake of 2,4-D into Arabidopsis cells during culture in 2,4-D containing medium and subsequent release of 2,4-D after transfer to growth regulator-free medium
was measured. (5) These low levels of released 2,4-D (0.2– 0.5 μm) could mimic the observed effects. Taken together these data suggest that the high intracellular 2,4-D content of Arabidopsis cultures may interfere with Arabidopsis somatic embryo development beyond the globular stage.
Received: 13 November 1997 / Revision received: 2 February 1998 / Accepted: 16 November 1998 相似文献
908.
Regeneration and large-scale propagation of bamboo (Dendrocalamus strictus Nees) through somatic embryogenesis 总被引:1,自引:0,他引:1
A complete protocol for large-scale propagation of Dendrocalamus strictus Nees by somatic embryogenesis has been developed. Seeds cultured on agar-solidified Murashige and Skoog (MS) medium supplemented
with 2,4-dichlorophenoxyacetic acid (2,4-D; 3×10–5
m) produced embryogenic callus from proliferation of the embryo. Somatic embryos formed in vitro multiplied rapidly (two- to
five fold every 5 weeks) on semi-solid MS medium containing 2,4-D (1×10–5
m), kinetin (Kn) (5×10–6
m), 1-indolebutyric acid (IBA) (2×10–6
m) and soluble polyvinylpyrrolidone (PVP) (250 mg l–1), or MS with 2,4-D (1×10–5
m), 6-benzylaminopurine (BAP) (1×10–5
m), and soluble PVP (250 mg l–1). Upon transfer to MS containing 1-naphthaleneacetic acid (NAA) (5×10–6
m), Kn (5×10–6
m) and soluble PVP (250 mg l–1), the dark-green embryos developed into healthy plantlets. Unrooted shoots, if any, obtained on the multiplication media
were rooted on MS major salts reduced to half strength supplemented with NAA (3×10–6
m) and IBA (2.5×10–6
m). The rooted plants were successfully transferred to soil in polythene bags with over 80% survival. Using this methodology,
more than 100,000 plants have been produced.
Received: 16 April 1998 / Revision received: 25 September 1998 / Accepted: 10 October 1998 相似文献
909.
Expression of freezing tolerance in the interspecific F1 and somatic hybrids of potatoes 总被引:5,自引:0,他引:5
Y.-K. H. Chen J. B. Bamberg J. P. Palta 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):995-1004
The expression of freezing tolerance was examined in interspecific F1 and somatic hybrids of potatoes using 20 species and 34 different combinations between hardy and sensitive species. In the
field, the frost tolerance of hybrids resembled either that of the hardy parent, the sensitive parent, or the parental mean,
depending on the species combination and the genomic ratio (ratio of the number of sets of chromosomes contributed from each
parent). Similar phenomena were observed when the non-acclimated freezing tolerance (NA) and the acclimation capacity (ACC)
(two independent genetic components of freezing tolerance) were evaluated separately under controlled environments. In general,
the expression level of freezing tolerance was higher in hybrids with more genomes contributed from the hardy parent than
from the sensitive parent. In addition, the effectiveness or combining ability of genes conferring freezing tolerance from
the hardy species also showed some influence on the expression of freezing tolerance. All three parameters, namely NA, ACC
and acclimated freezing tolerance (AA) (NA plus ACC), were significantly correlated to the frost tolerance exhibited in the
field. This indicates that the controlled freezing test used in this study could provide a good estimate of field performance.
The implications of these results in breeding for freezing tolerance in potatoes are discussed.
Received: 21 July 1998 / Accepted: 29 September 1998 相似文献
910.
L. T. Laferriere J. P. Helgeson C. Allen 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(8):1272-1278
The wild potato relative Solanum commersonii is reported to carry resistance to bacterial wilt disease caused by Ralstonia solanacearum. To overcome sexual incompatibilites due to differences in ploidy and endosperm balance numbers, somatic hybrids were made
that combine the S. tuberosum and S. commersonii genomes. The resulting somatic hybrid plants are vigorous, but their disease resistance level and their fertility was unknown.
We therefore tested the S. commersonii and S. tuberosum source material cv Superior, potato cv Atlantic and six somatic hybrid lines for resistance to a virulent strain of R. solanacearum (race 3, biovar 2) at 28°C. As expected, S. commersonii was significantly more wilt-resistant than the cultivated potatoes. In five of the six somatic hybrid lines, disease resistance
levels were similar to that of the resistant S. commersonii parent. The resistance level of the sixth somatic hybrid was intermediate, significantly different from both S. commersonii and S. tuberosum. In controlled crosses, the somatic hybrids in this study proved both to be male- and female-fertile and were self-compatible.
More importantly, the somatic hybrids can be crossed with S. tuberosum to produce viable seeds.
Received: 23 June 1998 / Accepted: 13 October 1998 相似文献