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31.
Mihály Czakó Jyan-Chyun Jang J. M. Herr László Márton 《Molecular & general genetics : MGG》1992,235(1):33-40
Summary A pea vicilin promoter-diphtheria toxin A (DTx-A) chain gene fusion was introduced into Arabidopsis and tobacco. The chimeric Dtx-A gene behaves as a dominant, seed-lethal, Mendelian factor, and the segregation ratios are consistent with the numbers of integrated copies as revealed by Southern blotting. Germination deficiency results from distinct developmental abnormalities, thus allowing genetic dissection of seed development. The endosperm is affected first in both species. In Arabidopsis, full cellularization of the initially syncytial endosperm does not take place, which results in shrinkage and a shriveled appearance of the mature dry seed. The embryo, which appears structurally normal and lacks visible lesions, ceases to develop at the partially recurved cotyledon stage and does not use the remaining endosperm. In tobacco, peripheral degeneration and premature termination of cellular endosperm development occurs at the cotyledon initiation stage. Lesions appear in the cotyledons at the advanced cotyledon stage, but the embryo continues to grow and attains nearly the same size and level of differentiation as mature wild-type embryos before degeneration and intracellular disintegration take place throughout. Accumulation of protein bodies and other cytoplasmic inclusions is very limited and occurs only in few cells. The timing and distribution of lesions follow a pattern typical for accumulation of protein bodies in wild-type seeds. These observations are consistent with expression of the vicilin promoter in the enlargement phase of cell differentiation. A novel tissue interaction arises, when the embryo uses up all the arrested endosperm: the embryo proves to be capable of absorbing the parenchyma layers of the integument, which are normally obliterated by, and incorporated into, the endosperm. The mature seed thus consists of a seed coat of one rigid cell layer, and a degenerated embryo. The genetic ablation technique has thus contributed to the establishment of the sequence of events and elucidation of the role of different cell lineages and tissues in seed development. 相似文献
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Do Quang Binh László E. Heszky Gabor Gyulai Anikó Csillag 《Plant Cell, Tissue and Organ Culture》1992,29(2):75-82
Cells of a 2-year-old suspension culture of rice (Oryza sativa L.), grown under 1.5% NaCl stress for 3 months, gave rise to plants through embryogenesis in different saline conditions. The high regeneration potential (59.6%) on salt-free medium decreased rapidly with increasing concentration of salt in the regeneration medium. At 1.25% NaCl, healthy shoots were developed in 14.9% of the cultures. Under 1.5% salt stress, embryo formation and embryo germination (6.1%) was observed but further development into plants was inhibited. Cells not pretreated with salt produced plants at a low frequency (2.6–4.2%) both in salt-free and low saline condition (0.75–1% NaCl). Cells pretreated for 3 months with 0.75% salt did not give rise to plants on all tested media. Plants regenerated from the salt-stressed cultures were transferred to soil and grew to maturity in a greenhouse.Abbreviations BA
6-benzyladenine
- CH
casein hydrolysate
- 2,4-D
2,4-dichlorophenoxyacetic acid
- NAA
1-naphthaleneacetic acid 相似文献
34.
Microstratification of phytoplankton in the large shallow Lake Balaton (Hungary) was studied during a 24 h period. Dissolved O2 showed biological stratification; flagellates exhibited a definite circadian rhythm. In the middle of the investigation a heavy storm broke out which was followed by the disappearance of differences between different layers of water. Storm-induced destratification is described by cluster-analysis. Abundances of dominant species changed differently in connection with the storm. Numbers of Nitzschia sp. increased due to stirring up from the sediment surface. Numbers of single-celled or colony-forming species (Cyclotella comta, Crucigenia quadrata, Coelosphaerium kuetzingianum) practically did not change. Numbers of all the three dominant filamentous species (Aphanizomenon fos-aquae f. klebahnii, Lyngbya limnetica, Planctonema lauterbornii) significantly decreased, which might be attributed to an unknown loss process and was followed by a competitive displacement by algae of small cell size. 相似文献
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Hydrolysis of 1,2-O-isopropylidene-3,5-di-O-methyl-α-d-glucofuranose by strong acid yielded 3,5-di-O-methyl-d-glucofuranose (6) and its 1,6-anhydride (10). The mechanism of the reaction giving 10 is discussed. On treatment with a catalytic amount of sodium methoxide, 1,2,6-tri-O-acetyl-3,5-di-O-methyl-d-glucofuranose (8) gives the 6-O-acetyl derivative, whereas complete deacetylation, and subsequent isomerization to the d-fructose derivative 16, takes place in the presence of 0.1m sodium methoxide. The structure of 16 was proved both chemically and spectroscopically. Reduction of 6 or 8 with a borohydride afforded 3,5-di-O-methyl-d-glucitol.2 相似文献
38.
László Orlóci 《Plant Ecology》1976,32(2):117-120
Summary TRGRPS can detect groups or signal if discrete groups cannot be found in a sample. The present paper elaborates on the concepts, describes the algorithm and provides illustrations from syntaxonomy. A computer program (TRGRPS.BAS) is available from the author upon request.Contribution from the Working Group for Data Processing in Phytosociology, International Society for Vegetation Science. For nomenclature of species see Lausi, Beeftink & Kortekaas (1975).The research project, from which this paper summarizes partial results, is supported by a National Research Council of Canada grant. Computer time was provided by the University of Western Ontario. 相似文献
39.
Summary This paper elaborates on the notion of homogeneity in plant populations and its quantification. It describes a method for testing homogeneity without the need to make assumptions about generalized distributions. The implementation of the method is illustrated through actual numerical examples.This paper presents results from a study of plant populations for which a National Research Council of Canade grant has been received (L. Orlóci). 相似文献
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