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11.
Expression of a chimeric gene encoding the coat protein (CP) of tobacco mosaic virus (TMV) in transgenic tobacco plants confers resistance to infection by TMV. We investigated the spread of TMV within the inoculated leaf and throughout the plant following inoculation. Plants that expressed the CP gene [CP(+)] and those that did not [CP(-)] accumulated equivalent amounts of virus in the inoculated leaves after inoculation with TMV-RNA, but the CP(+) plants showed a delay in the development of systemic symptoms and reduced virus accumulation in the upper leaves. Tissue printing experiments demonstrated that if TMV infection became systemic, spread of virus occurred in the CP(+) plants essentially as it occurred in the CP(-) plants although at a reduced rate. Through a series of grafting experiments, we showed that stem tissue with a leaf attached taken from CP(+) plants prevented the systemic spread of virus. Stem tissue without a leaf had no effect on TMV spread. All of these findings indicate that protection against systemic spread in CP(+) plants is caused by one or more mechanisms that, in correlation with the protection against initial infection upon inoculation, result in a phenotype of resistance to TMV. 相似文献
12.
In ecological models, the timing of amphibian metamorphosis is dependent upon rate of larval growth, e.g., tadpoles that experience a decrease in growth rate can initiate metamorphosis early. Recent authors have suggested that this plasticity may be lost at some point during the larval period. We tested this hypothesis by exposing groups of tadpoles of the gray treefrog, Hyla versicolor, to different growth schedules. In endocrine models, metamorphosis is dependent on thyroxine levels and thyroxine is antagonized by prolactin (amphibian larval growth hormone), consistent with the idea that a rapidly growing tadpole can delay metamorphosis. Thus, we also manipulated the rate of development by supplementing or maintaining natural thyroxine levels for half of the tadpoles in each growth treatment. All tadpoles that received thyroxine supplements metamorphosed at the same time regardless of growth history. They also metamorphosed earlier than tadpoles not treated with thyroxine. Tadpoles not given thyroxine supplements metamorphosed at different times: those growing rapidly during day 15-34 metamorphosed earlier than tadpoles growing slowly. Growth rate before day 15 and after day 34 had no effect on metamorphic timing. The difference in larval period between these rapidly growing tadpoles and their sisters given thyroxine treatments was less than the same comparison for tadpoles that grew slowly during the same period. This apparent prolactin/thyroxine antagonism did not exist after day 34. These results are consistent with the hypothesis of a loss of plasticity in metamorphic timing. 相似文献
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14.
Role of P30 in replication and spread of TMV 总被引:2,自引:1,他引:1
The P30 movement protein (MP) of tobacco mosaic virus is essential for distribution of sites of replication within infected cells and for cell–cell spread of infection. MP is an integral membrane protein and in early and mid-stages of infection causes severe disruption of the cortical endoplasmic reticulum (ER). MP also associates with microtubules, and in late stages is targeted for degradation by the 26S proteosome. During these stages, the ER regains its normal pre-infection configuration. Viral RNA is associated with ER and microtubules in the presence of MP. The MP is phosphorylated and mutation of the phosphorylated amino acid reduced association of MP with the ER, plasmodesmata, and microtubules, and altered the stability of the MP. The nature of the association of MP with vRNA and ER and microtubules, and the role of phosphorylation of MP in each of these functions, if any, remains to be determined. 相似文献
15.
Franck-Duchenne Martine Wang Yuwen Ben Tahar Sofia Beachy Roger N. 《Plant Cell, Tissue and Organ Culture》1998,53(2):79-84
In vitro regeneration of sweet pepper (Capsicum annuum L. cvs Jupiter and Pimiento Perfection) has been performed via direct
organogenesis. The resulting shoot-buds were placed on media containing 24-epi-brassinolide (EBR) 0.1 μM, a plant steroid
lactone, in the presence or absence of zeatin 9.1 μM plus GA3 5.2 μM for further stem elongation. Different responses to these
treatments were recorded depending upon the protocols used and the genotypes tested. It appears that EBR does not always act
directly on stem elongation but may be an elicitor and/or an enhancer of elongation in concert with endogenous and other exogenously
added growth regulators. Elongated shoots were easily rooted with alpha-naphtalenacetic acid 0.5 μM (0.1 mgl-1) and transfered
to soil, and following acclimation were taken to maturity in the greenhouse.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Elizabeth A. Bray Satoshi Naito Nai-Sui Pan Edwin Anderson Philip Dubé Roger N. Beachy 《Planta》1987,172(3):364-370
Soybean (Glycine max (L.) Merr.) seeds contain the storage protein -conglycinin, encoded by a multigene family. -Conglycinin consists of three subunits; , , and . A genomic clone for a -subunit of -conglycinin has been characterized by restriction-enzyme mapping and hybrid selected in-vitro translation followed by immunoprecipitation. In order to determine the developmental regulation of this -subunit gene, its expression was studied in seeds of transgenic petunia (Petunia hybrida) and tobacco (Nicotiana tabacum L.) plants. The -subunit expressed in seeds of petunia and tobacco was recognized by anti--conglycinin serum at a relative molecular mass of 53 000, equivalent to that of the native protein. Separation of the petunia-seed proteins by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed that multiple isoelectric forms of the -subunit were produced. There was approximately a twofold variation in the accumulation of the -subunit protein in the mature seeds of transgenic petunia plants, each containing a single -subunit gene. However, the level of protein accumulation in mature seeds and the amount of -subunit mRNA in developing seeds was not correlated. Accumulation of the -subunit protein in transgenic seeds was less than the -subunit protein that accumulated in transgenic petunia seeds containing a single -subunit gene and less than the amount of the -subunit in mature soybean seeds which contain 8–13 -subunit genes. In transgenic tobacco plants, the accumulation of the -subunit protein in seeds was generally well correlated with the number of genes that were incorporated in the different transformants.Abbreviations kb
kilobase
- kDa
kilodalton
- Mr
relative molecular mass
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis 相似文献
17.
Selective inhibition of photosystem II in spinach by tobacco mosaic virus: an effect of the viral coat protein 总被引:6,自引:0,他引:6
Leaves of Spinacia oleracea inoculated with tobacco mosaic virus (TMV) strain PV230 develop mild chlorotic and mosaic symptoms of infection. Thylakoid membranes isolated from these infected leaves showed a reduced Fv/Fm ratio for chlorophyll fluorescence kinetics, at 25 degrees C. The photosystem II (PS II)-mediated electron-transport rate was inhibited 50%, whereas PS I activity was unaffected by virus infection. Protein analysis indicated that TMV coat protein was associated with thylakoids, in particular with the PS II fraction. The results demonstrate that TMV-infected S. oleracea shows inhibition of photosynthetic electron transport through PS II. We propose that the inhibition of photosynthetic activity results from the association of viral coat protein with the PS II complex. 相似文献
18.
19.
The disease holoprosencephaly is the basis of the most common structural anomaly of the developing forebrain in humans. Numerous teratogens when administered during early gastrulation, have been associated with this condition. Recent studies have characterized molecules expressed in the prechordal plate which are critical for normal brain formation. Perturbation of signaling pathways involving these molecules have been shown to cause holoprosencephaly in humans and other organisms. 相似文献
20.
The ability to regulate spatial and temporal expression of genes is a useful tool in biotechnology as well as studies of functional genomics. Such regulation can provide information concerning the function of a gene in a developmental context while avoiding potential harmful effects due to constitutive overexpression of the gene. A GUS gene construct that uses the ecdysone receptor-based chemically inducible system and several different tissue-specific promoters was introduced into the model plant Arabidopsis thaliana and into the crop plant Brassica juncea. Here we describe the results of studies showing that this system provides both temporal and spatial control of transgene expression, and confirm that this system is useful for tissue-specific and temporal induction of gene expression in A. thaliana and B. juncea. 相似文献