摘要:

AbstractAlthough a wide range of mutations in the nuclear genome also affect chloroplast biogenesis, their pleiotropic nature often limits their use in studying nuclear genes that regulate or facilitate chloroplast development. However, many mutations that cause a high‐chlorophyll‐fluorescent (hcf) phenotype exhibit limited pleiotrophy, causing the loss of functionally related sets of chloroplast polypeptides. Several hcf mutations are described that result in the loss of one specific protein complex from the thylakoid membrane. Chlorplast and cytosolic mRNAs coding for component polypeptides of the missing complex are unaffected in the mutants, suggesting that each mutation disrupts some process in the synthesis and assembly of the missing complex. Another hcf mutation causes both the loss of three protein complexes and grossly abnormal thylakoid membrane structures. The primary effect of this mutation might be in the assembly of thylakoid membranes or in the stable accumulation of the three protein complexes. Two other hcf mutations are more pleiotropic.Hcf*−38causes a quantitative reduction of many chloroplast proteins and a reduction of some chloroplast RNAs, including several splicing intermediates.Hcf*−7causes a major reduction of all chloroplast‐encoded proteins examined. The range of pleiotropic effects of hcf mutations indicates that the mutations identify nuclear genes whose products are involved in a number of different steps in chloroplast devclopment. Because some of the mutations described have been generated by transposon insertions, they can be cloned using the transposon to identify the muta

ISSN:0192-253X    

DOI:10.1002/dvg.1020080503

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020080504

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe light‐regulated chloroplastpsbA gene encoding the QBprotein has been cloned from rice(Oryza sativaL.), and the nucleotide sequence has been determined. Comparison of nucleotide sequences and derived amino acid sequences between species indicates a high degree of conservation of the primary structure. Comparison of promoter regions from the light‐inducible chloroplastpsbA,rbcL, andpsaA genes indicates conservation of the prokaryotic‐like promoter elements in all three genes and of a —21 box common only topsbA andrbcL promoter regions. No other putative regulatory signals were found based on nucleotide se

ISSN:0192-253X    

DOI:10.1002/dvg.1020080505

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractAuxin (2,4‐dichlorophenoxyacetic acid) starvation of soybean cell suspension leads to the arrest of cell division after about 4 days. Readdition of 4 μM of auxin enables cells to divide again after a lag phase of 1 day. Accumulation of a well‐known isoflavonoid‐derived phytoalexin (glyceollin) and a highly elevated catalytic activity of two of the enzymes associated with glyceollin biosynthesis, phenylalanine ammonia‐lyase and chalcone isomerase, is described. Moreover, stimulation of catalytic activity of the enzymes chitinase and β 1,3‐glucanase, which are involved in plant defense against pathogens, is observed at the same time. By comparing the patterns of in vitro protein synthesis, we have identified groups of polypeptides whose synthesis is either positively or negatively regulated by auxin. Some of these polypeptides are also induced by fungal elicitor treatment. Our results provide evidence of a dual control by auxin and fungal elicitor working in an opposite manner on the inducibility of enzymes and proteins that play a role in the induced defense response

ISSN:0192-253X    

DOI:10.1002/dvg.1020080506

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractTranscription of heat‐shock protein genes in soybean can be induced by high temperature stress leading to a transient expression of heat‐shock proteins. We have tested whether the replacement of a native heat‐shock promoter by a viral promoter results in constitutive transcript levels of the respective gene in transgenic plants. The 35S‐transcript promoter of the cauliflower mosaic virus was linked to the protein‐coding region of the genomic heat‐shock genehs6831, encoding a 17.6‐kD heat‐shock protein of soybean. After transformation of tobacco plants with this chimeric construction using a disarmedAgrobacteriumbinary vector, abundant mRNA levels were detected in transgenic plants. The steady‐state level of this mRNA at 25°C was equal to that generated by the native heat‐shock promoter at 40°C; however, it was markedly reduced by heat shock applied to the transgenic plants. These findings suggest a sufficiently high stability of heat‐shock mRNA produced at the normal growth temperature to direct constitutive expression of heat‐shock proteins. The application of constitutive gene expression for the investigation of the

ISSN:0192-253X    

DOI:10.1002/dvg.1020080507

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe soybean(Glycine max[L.] Merr.) contains two urease isozymes whose expression is regulated in a tissue‐specific and temporal manner. The ubiquitous urease is expressed in all tissues examined (leaf, embryo, seed coat, cell culture); the embryo‐specific urease is synthesized exclusively in the developing embryo. The embryo‐specific urease accumulates during seed development while the ubiquitous urease is found in highest levels during early development of both leaves and seeds. We have isolated mutants which fall in three phenotypic classes lacking one or both urease isozyme activities. Genetic analysis has thus far identified three unlinked loci which control the expression of urease(s). Genomic and cDNA clones of urease structural genes have also been recovered and we are working to assign these to genetic loci by sequence and RFLP analyses. That the ubiquitous urease isozyme is expressed in cell culture makes it possible to include cell culture in physiological and developmental studies. Additionally, we have developed direct selections for urease‐negative mutants, and their revertants, in cell culture. These selections will facilitate the study of the expression of cloned urease genes in genetically transformed

ISSN:0192-253X    

DOI:10.1002/dvg.1020080508

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe major chlorophyll a/b light harvesting complex (LHCII) of mesophyll chloroplasts is normally assembled late during chloroplast morphogenesis. LHCII occurs at greatly reduced levels in bundle sheath chloroplasts of maize. In order to understand the normal regulatory mechanisms we are examining nuclear maize mutants that alter either (1) the assembly timing or (2) the steady state level of LHCII in mature mesophyll thylakoids. We have found a delayed greening mutant,v24(on chromosome arm 2L), that unmasks a second unlinked locus,Mof*, that can mediate LHCII assembly timing. The polypeptides of LHCII are encoded by the nuclear multigenecabfamily. We find that two alleles atMof*regulate the steady state level ofcabmRNA in parallel to their effect on LHCII assembly timing: The genotypeMof*‐1 Mof*‐1 v24 v24corresponds to reducedcabmRNA and late LHCII assembly timing, whileMof*‐2 Mof*‐2 v24 v24corresponds to reducedcabmRNA and late LHCII assembly timing. A second group of mutations(Oy‐700, pg11andpg12reduces LHCII levels in mesophyll thylakoids. This is the first report thatpg11andpg12)reduce the LHCII of mesophyll thylakoids. The basis ofpg11andpg12is unknown. Mutations at theOylocus block the chlorophyll biosynthetic enzyme, protopor‐phyrin IX Mg‐chelatase. Heterozygotes of the codominant mutationOy‐700with the normal allele(Oy)have reduced LHCII. We have defined genetic backgrounds that suppress and those that do not suppress theOy‐700 Oyphenotype under certain conditions: (1) reduced light intensities (200 μE cm−2sec−1) and

ISSN:0192-253X    

DOI:10.1002/dvg.1020080509

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe nuclear DNA of eukaryotic organisms is associated with a variety of proteins, which together make up what is called “chromatin.” Chromatin serves to package all genes into higher‐order structures such as nucleosomes, solenoids, and loop domains. Tight packing of a particular gene and its regulatory sequences does not allow the approach of RNA I or II polymerase proteins. Before or during the activation of such an inactive gene its chromatin has to adopt a relaxed, more “open” configuration. This altered chromatin can be probed by its higher sensitivity toward nucleases, such as DNAse I or S1 nuclease, and the appearance of DNAse I‐hypersensitive sites. These sites may constitutively be present or may be induced, and they can be mapped to specific DNA sequence motifs. In many cases, such sites are delimited by non‐B‐DNA, notably Z‐DNA, which in turn may form part of enhancer elements. The Z‐DNA configuration may be induced or maintained by methylation of cytosyl residues within underlying sequences.Two plant gene model systems have been selected to probe their chromatin structure. Constitutively expressed T‐DNA genes ofAgrobacteriuminduced tobacco crown gall tumor cells have been shown to be organized in canonical nucleosomes, to be more sensitive to DNAse I than the bulk of host chromatin, and to contain a series of six constitutive DNAse I‐hypersensitive sites. Inducible ribulose‐1,5‐bisphosphate carboxyl‐ase/oxygenase small subunit (rbcS) genes of pea are rearranged into a nuclease‐sensitive format upon activation by light, especially in their promoter region. The rbcS promoter harbors a series of five constitutive DNAse I‐hypersensitive sites and one light‐inducible site, which is surrounded by potential regulatory sequences (enhancer cores, inverted repeats). The 3′ region of rbcS genes also contains constitutive sites. Methylation/demeth‐ylation of Alu I‐, Fnu4H1‐, HaeIII‐, Sau3AI‐, and Sau 96I sequences in rbcS promoters does not pla

ISSN:0192-253X    

DOI:10.1002/dvg.1020080510

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractMicrotubules are important components of the cytoskeleton of plant cells and play key roles in plant growth and morphogenesis. Recent molecular studies have begun to elucidate the structure and expression of plant genes coding for the major components of microtubules, α‐ and β‐tubulin. Tubulin amino acid sequences deduced from the DNA sequences of eight higher plant tubulin genes are 79–87% homologous with constitutively expressed mammalian tubulins. The genome of the model plant systemArabidopsis thalianacontains four dispersed α‐tubulin sequences and at least seven β‐tubulin sequences, only two of which appear to be linked. Of the fiveA. thalianagenes whose expression has been analyzed, the transcripts of one α‐tubulin and one β‐tubulin gene are constitutively expressed in roots, leaves, and flowers. A second α‐tubulin gene is expressed predominately in flowers; the transcripts of the second and third β‐tubulin genes are found predominately in leaves

ISSN:0192-253X    

DOI:10.1002/dvg.1020080511

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY

摘要:

AbstractThe general structure of the plant histone genes has been deduced from the comparison of the nucleotide sequences of ten H3 and H4 genes of maize (3 H3 and 3 H4) andArabidopsis thaliana(2 H3 and 2 H4). The five H3 and five H4 genes encode the same proteins, respectively. The 5′‐flanking regions contain the classical histone gene‐specific consensus sequences. In addition, a conserved octanucleotide CGCGGATC was found in all plant histone genes at 200–250 nucleotides before the initiation codon.All six maize H3 and H4 genes are transcribed during early germination as shown by nuclease S1 mapping and reverse transcriptase primer extension experiments. The mRNA 5′‐ends are located within the consensus sequence CCAA/CT/C. The 3′‐ends lack the classical T‐hyphenated dGC‐rich palindromic structure and possess long nontranslated sequences.In both plants the multiple copies of the H3 and H4 genes are organized into multigenic families. The genes of each family show a similar proximal environment, suggesting that they originate from the duplication o

ISSN:0192-253X    

DOI:10.1002/dvg.1020080512

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1987

数据来源: WILEY