ISSN:1040-4651    

DOI:10.1105/tpc.2.1.1

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

Peroxidases are a family of isoenzymes found in all higher plants. However, little is known concerning their role in growth, development, or response to stress. Plant peroxidases are heme-containing monomeric glycoproteins that utilize either H2O2 or O2 to oxidize a wide variety of molecules. To obtain more information on possible in planta functions of peroxidases, we have used a cDNA clone for the primary isoenzyme form of peroxidase to synthesize high levels of this enzyme in transgenic plants. We were able to obtain Nicotiana tabacum and N. sylvestris transformed plants with peroxidase activity that is 10-fold higher than in wild-type plants by introducing a chimeric gene composed of the cauliflower mosaic virus 35S promoter and the tobacco anionic peroxidase cDNA. The elevated peroxidase activity was a result of increased levels of two anionic peroxidases in N. tabacum, which apparently differ in post-translational modification. Transformed plants of both species have the unique phenotype of chronic severe wilting through loss of turgor in leaves, which was initiated at the time of flowering. The peroxidase-induced wilting was shown not to be an effect of diminished water uptake through the roots, decreased conductance of water through the xylem, or increased water loss through the leaf surface or stomata. Possible explanations for the loss of turgor, and the significance of these types of experiments in studying isoenzyme families, are discussed.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.7

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

Protein changes induced by salinity stress were investigated in the roots of the salt-sensitive rice cultivar Taichung native 1. We found eight proteins to be induced and obtained partial sequences of one with a molecular mass of 15 kilodaltons and an isoelectric point of 5.5. Using an oligonucleotide probe based on this information, a cDNA clone, salT, was selected and found to contain an open reading frame coding for a protein of 145 amino acid residues. salT mRNA accumulates very rapidly in sheaths and roots from mature plants and seedlings upon treatment with Murashige and Skoog salts (1%), air drying, abscisic acid (20 microM), polyethylene glycol (5%), sodium chloride (1%), and potassium chloride (1%). Generally, no induction was seen in the leaf lamina even when the stress should affect all parts of the plant uniformly. The organ-specific response of salT is correlatable with the pattern of Na+ accumulation during salt stress.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.19

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

Tobacco was transformed with a gene coding for an S-locus-specific glycoprotein of Brassica oleracea. The resulting transgenic plants showed tissue-specific and developmentally regulated expression of the introduced gene. Immunolocalization experiments showed that the Brassica gene was expressed in the stylar transmitting tissue of the transgenic plants. The pattern of expression of the introduced gene was more similar to that of the S-associated genes of Nicotiana alata than to expression in Brassica. Self-incompatibility was not conferred by the introduced gene.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.29

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

A tobacco plant transformed with a Brassica oleracea SLG-22 gene was analyzed by immunocytochemical methods to determine the localization of the transgene-encoded protein product. Immunolabeling was observed in the pistil along the path followed by pollen tubes after pollination. S-antigen accumulated in the intercellular matrix of the transmitting tissue of the style and its continuation in the basal portion of the stigma and outside a few special cells of the placental epidermis of the ovary. This pattern of S-antigen distribution closely resembles that described for the S-associated glycoproteins of self-incompatible Nicotiana alata and differs from its distribution in B. oleracea.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.39

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

To study protein secretion in plant cells, we established and evaluated a model system based on transient synthesis of heterologous proteins in tobacco protoplasts. We show that the nonsecretory enzymes phosphinothricin acetyl transferase, neomycin phosphotransferase II, and beta-glucuronidase are secreted when targeted to the lumen of the endoplasmic reticulum by signal peptide-mediated translocation. These data are consistent with the view that secretion can occur independent of active sorting mechanisms by nonspecific migration through the exocytic pathway. However, the rate of secretion differs significantly among these enzymes. Furthermore, the presence of signal sequences was found to be correlated with a reduction of the levels of the encoded gene products. This is the result of post-transcriptional events that limit either synthesis or stability of the proteins in vivo.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.51

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

The effect of progressive 5[prime] deletions within a potato proteinase inhibitor II promoter on wound-inducible expression of the chloramphenicol acetyltransferase (CAT) gene in leaves of transgenic tobacco plants was analyzed. After deletion of a region ranging from position -1300 to -700 with respect to the transcription start site, promoter activity was markedly reduced but still wound-inducible. Further deletion of approximately 200 base pairs resulted in a promoter activity that was below the detection limit, proving that the activity of the proteinase inhibitor II promoter is controlled by sequences upstream of position -514. Addition of the enhancer of the 35S promoter of the cauliflower mosaic virus (CaMV) either 5[prime]upstream or 3[prime] downstream of chimeric genes consisting of different proteinase inhibitor II promoter deletions (-700, -514, -210) fused to the CAT gene led to wound-inducible CAT gene expression in a fraction of transgenic plants containing either the "-700" or "-514" promoters, indicating the presence of wound-responsive elements in the promoter-proximal region. A fragment of the proteinase inhibitor II promoter comprising sequences between positions -1300 and -195 is able to confer wound-inducible expression to an inactive CaMV 35S promoter truncated at position -90 in either orientation, proving that this fragment displays wound-specific, enhancer-like properties. In addition, data are presented excluding that the proteinase inhibitor II 3[prime]end is of importance for wound-inducible gene expression.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.61

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

Relatively little is known about the mechanisms that govern the expression of plant mitochondrial genomes. We have addressed this problem by analyzing the transcriptional activity of different regions of the maize mitochondrial genome using both in vivo and isolated mitochondrial pulse-labeling systems. The regions examined included the protein genes atpA, atp6, and coxII, the 26S, 18S, and 5S rRNA genes, and sequences surrounding the rRNA genes. The rRNAs were found to be transcribed at rates fivefold to 10-fold higher than the protein genes. These rate differences are comparable with the differences in abundance of these species in the total or steady-state RNA population. Pulse-labeled RNA unexpectedly detected transcription of all regions examined, including approximately 21 kilobases of presumed noncoding sequences flanking the rRNA genes for which stable transcripts were not detected. The results obtained with RNA labeled for short pulses in vivo and in isolated mitochondria were similar, suggesting that isolated mitochondria provide a faithful run-on transcription assay. Our results indicate that the absence in total RNA of transcripts homologous to a given region of maize mitochondrial DNA does not necessarily exclude transcriptional activity of that region and that both transcriptional and post-transcriptional processes play important roles in maize mitochondrial genome expression.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.71

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB

摘要:

Three different nuclear factors recognizing short AT-rich DNA sequences were identified in different organs of soybean. One factor (NAT2) was found to be present in mature nodules, another factor (NAT1) was detected in roots and nodules, and a third one (LAT1) was only observed in leaves. All three factors recognized several DNA sequences in the promoter region of the soybean nodulin N23 gene. Footprinting, deletion, and point mutation analyses revealed different binding properties for all three factors and further showed that even single base pair substitutions had a dramatic effect on binding affinity. The LAT1 and NAT1 factors were released from chromatin by extraction with a low-salt buffer and were soluble in 2% trichloroacetic acid, implying a relationship to high-mobility group (HMG) proteins. DNA binding studies further indicated a functional relationship of these factors to the human HMG I protein. Purification of the LAT1 factor from leaf nuclei revealed the presence of two polypeptides with molecular masses of 21 kilodaltons and 23 kilodaltons, respectively, binding the same DNA sequence with equal affinity.

ISSN:1040-4651    

DOI:10.1105/tpc.2.1.85

出版商:American Society of Plant Biologists    

年代:1990

数据来源: ASPB