Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
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We studied the symbiotic behaviour of 20 independent Tn5 mutants of Rhizobium tropici strain CIAT899 that were deficient in exopolysaccharide (EPS) production. The mutants produced non-mucoid colonies, were motile, grew in broth cultures at rates similar to those of the parent, and produced significantly less EPS than did CIAT899 in broth culture. A genomic library of strain CIAT899, constructed in pLA2917, was mobilized into all of the mutants, and cosmids that restored EPS production were identified. EcoRI restriction digests of the cosmids revealed nine unique inserts. Mutant complementation and hybridization analysis showed that the mutations affecting EPS production fell into six functional and physical linkage groups. On bean, the mutants were as efficient in nodulation and as effective in acetylene reduction as strain CIAT899, induced a severe interveinal chlorosis, and all but one were less competitive than CIAT899. On siratro, CIAT899 induced nodules that were ineffective in acetylene reduction, whereas the EPS-deficient mutants induced effective nodules. Microscopic examination of thin sections showed that nodules from both siratro and bean plants inoculated with either CIAT899 or an EPS-deficient mutant contained infected cells. These data indicate that EPS is not required for normal nodulation of bean by R. tropici, that it may contribute to competitiveness of R. tropici on bean, and that the loss of EPS production is accompanied by acquisition of the ability to reduce acetylene on siratro.
Mol Microbiol 1992 Nov
PMID:Molecular and symbiotic characterization of exopolysaccharide-deficient mutants of Rhizobium tropici strain CIAT899. 145 54

The response of Nicotiana tabacum to tentoxin (chlorosis) is inherited with chloroplasts. N. tabacum var. Xanthi, a tentoxin-resistant line, was used to pollinate tentoxin-sensitive N. tabacum line 92, an alloplasmic male-sterile line containing N. undulata plastids. The seeds were mutagenized with nitrosomethylurea and germinated in the presence of tentoxin. Two percent of the seedlings had green sectors in their first true leaves. These plants were grown to maturity under non-selective conditions. Homogeneous tentoxin-resistant lines were obtained in the third generation. DNA analysis indicated, however, that selection for paternal plastids, rather than mutagenesis of maternal ones, had occurred in the tentoxin-resistant progeny. Mitochondria, which were not under selection pressure, were inherited maternally as expected. Inheritance of tentoxin-resistant paternal plastids did not require seed mutagenesis. Normally germinated seedlings that were kept under tentoxin selection consistently produced a low level of resistant green sectors in their first true leaves. Thus, normal, low-frequency transmission of paternal plastids in N. tabacum can be directly revealed by using tentoxin.
Mol Gen Genet 1991 Feb
PMID:Direct selection for paternal inheritance of chloroplasts in sexual progeny of Nicotiana. 200 69

Six satellite RNAs of cucumber mosaic virus (CMV) could be differentiated on the basis of symptom expression they elicit in tomato and tobacco, and all but two could be differentiated by gel electrophoretic migration. Three of the satellite RNAs (B2-sat, G-sat, and WL1-sat RNA) ameliorated the symptoms induced by CMV on tomato, whereas three others (B1-sat, B3-sat, and WL2-sat RNA) induced chlorosis on tomato, the extent and nature of which was CMV-strain dependent. By contrast, B2-sat RNA induced chlorosis in tobacco, whereas WL1-sat and G-sat RNAs did not. Thus, the symptoms observed were dependent on the host species, the particular satellite RNA, and also the strain of helper virus, suggesting that a complex association of at least three factors is involved in symptom elicitation. Comparisons of the nucleotide sequences of pairs of satellite RNAs inducing the various chlorotic responses suggest that only a few nucleotide changes in specific domains are required for the elicitation of different host responses.
Mol Plant Microbe Interact 1988 Apr
PMID:Pathogenicity regulation by satellite RNAs of cucumber mosaic virus: minor nucleotide sequence changes alter host responses. 298 Feb 2

In an effort to determine if particular regions of the cauliflower mosaic virus (CaMV) genome could be associated with particular phenotypic characters, strains of CaMV differing markedly in biological properties were recombined to produce hybrids. DNA from pairs of (infectious) genomic clones was cleaved with restriction endonucleases, then mixed and ligated. Recombinants were found by screening transformants in E. coli, or by selection in vivo for infectious hybrids. Recombinants in infected turnip plants were characterized by restriction endonuclease mapping of their DNA to confirm the hybrid genotype. New hybrid strains that induced less severe disease, or conversely, more severe disease than either parent were observed. The experiments revealed that typical disease expression, consisting of leaf chlorosis and mottling, mapped to a genome segment containing open reading frame VI (ORF VI) and the full-length promoter. This basic disease symptom was found to be influenced by other regions of the genome. Insect transmissibility mapped to ORF II. The ability to develop generalized infections in solanaceous plants was tested in hybrids between CaMV CM1841 and a variant that infects Datura stramonium systemically. In this case the systemic mobilization of virus appeared to be controlled by ORF VI, suggesting that this gene may function in cell-to-cell movement of virus.
J Mol Appl Genet 1984
PMID:Expression of disease symptoms in cauliflower mosaic virus genomic hybrids. 653 Jun 2

A number of satellite RNAs of cucumber mosaic virus (CMV) can induce chlorosis in either tobacco or tomato. A region containing the chlorosis domain was delimited, and one nucleotide position (153) regulating chlorosis induction as well as the nucleotide position (149) controlling the host specificity for chlorosis were identified. A cDNA clone of the B5-sat RNA was modified by site-directed mutagenesis to identify other nucleotides affecting chlorosis itself, as well as the extent of chlorosis and the helper virus-strain specificity for chlorosis. Four nucleotides conserved in chlorosis-inducing satellite RNAs (positions 127, 148, 149, 158) as well as two nucleotides within the chlorosis-induction domain that vary among chlorosis-inducing satellite RNAs (170, 171) were altered. Only substitutions at nucleotide positions 127 and 171 did not affect expression of the chlorosis phenotype. Alteration of position 148 affected satellite RNA accumulation. The pleiotropic effects of various sequences within the chlorosis-induction domain are discussed relative to particular sequence contexts in different chlorosis-inducing RNAs.
Mol Plant Microbe Interact
PMID:The chlorosis-induction domain of the satellite RNA of cucumber mosaic virus: identifying sequences that affect accumulation and the degree of chlorosis. 801 41

Transgenic tobacco plants containing a mouse metallothionein-I (MT-I) gene fused to the cauliflower mosaic virus 35S (CaMV 35S) promoter and nopaline synthase (nos) polyadenylation site were obtained by transforming tobacco leaf discs with an Agrobacterium tumefaciens strain carrying the chimaeric gene. Transformants were directly selected and rooted on medium containing cadmium and kanamycin. A total of 49 individual transgenic tobacco plants were regenerated. Among them 20% showed a very high expression level and their growth was unaffected by up to 200 microM cadmium, whereas the growth of control plants was severely affected leaf chlorosis occurred on medium containing only 10 microM cadmium. The concentration of microM cadmium. The concentration of MT-I in leaves of control and transgenic tobacco was determined with Cd/haemoglobin saturation assay, a polarographic method and western blotting. In addition, seeds from self-fertilized transgenic plants were germinated on medium containing toxic levels of cadmium and scored for tolerance/susceptibility to this heavy metal. The ratio of tolerant to susceptible plants was 3:1 indicating that the metallothionein gene is inherited as a single locus.
Plant Mol Biol 1994 Jan
PMID:Expression of mouse metallothionein-I gene confers cadmium resistance in transgenic tobacco plants. 811 Oct 36

With a view to exploring its use as a metal-binding factor in transgenic plants we prepared the alpha-domain of metallothionein by reconstitution of rabbit apometallothionein and proteolysis of MT-1 and MT-2 with subtilisin. The isolated alpha-domains were characterised by UV and CD spectroscopy Double-Stranded. DNA encoding the alpha-domain (106 bp) of the human MT-IA was constructed from chemically synthesized oligomers by repair synthesis and enzymatic ligation, cloned into pUC19 and sequenced. A expression construct containing the cloned alpha-domain was introduced into tobacco cells on a disarmed Agrobacterium tumefaciens Ti-plasmid. Transformed tobacco cells were selected and regenerated on medium containing cadmium and kanamycin. The growth of roots and shoots of transformants was unaffected by up to 100 microM cadmium, whereas control plants showed severe inhibition of root and shoot growth, and chlorosis of leaves on medium containing only 10 microM cadmium. Southern hybridization confirmed the presence of the transgene in the transformed plant tissues. The concentration of human alpha-domain peptides in transgenic tobacco leaves was determined by the Cd/hemoglobin saturation assay and polarography using the rabbit alpha-domain as standard. The results indicate that the alpha-domain, one of two domains in MT molecules, is not only stable in vitro, but is also expressed efficiently and functions independently in transgenic plant cells.
Mol Gen Genet 1994 Mar
PMID:Alpha-domain of human metallothionein IA can bind to metals in transgenic tobacco plants. 815 17

Turnip yellow mosaic virus is a positive-strand RNA virus that produces light green or yellow-green mosaic symptoms in Chinese cabbage plants. We have characterized a strain that produces nearly uniform yellow-green chlorosis in systemically infected Chinese cabbage leaves. The increased symptom severity is due to the single nucleotide substitution U1888-->C, which results in a tyrosine to histidine substitution in the movement protein encoded by ORF-69. Coding by the overlapping ORF-206 is not affected. The mutation results in fourfold higher accumulations of viral products in systemically infected Chinese cabbage leaves but does not affect viral replication in isolated protoplasts. These results suggest that the increased viral yield and symptom severity result from improved viral spread in the host plant. These effects were specific to Chinese cabbage, since neither viral yield nor symptoms in turnips were affected by the U1888-->C mutation.
Mol Plant Microbe Interact
PMID:Increased viral yield and symptom severity result from a single amino acid substitution in the turnip yellow mosaic virus movement protein. 832 45

Gene VI of cauliflower mosaic virus (CaMV) is an important determinant of symptom expression during infection. We have constructed a series of transgenic Arabidopsis lines that express gene VI protein (P6) from two CaMV isolates (Bari-1 and Cabb B-JI) that cause mild and severe symptoms, respectively, in Arabidopsis, and from a recombinant virus (Baji-31) with a hybrid gene VI that causes very severe symptoms. From 41 transgenic lines analyzed, 17 showed symptom-like phenotypes that ranged from mild vein chlorosis to severe chlorosis and stunting. P6 levels in transgenic lines varied from undetectable in the lowest expressors to levels greater than those in CaMV-infected plants. There was a strong correlation between phenotype severity and the level of P6, and with the gene VI origin in the order, Baji-31 > B-JI > Bari-1. This was similar to symptom severity in Arabidopsis infected with the respective CaMV variant. We also found that transgenic P6 accumulated in inclusion bodies that were similar to those found in infected plants but lacking virions. We conclude that expression of P6, in the absence of virus replication, elicits a subset of the host symptom responses normally observed during infection and that the level, sequence, and possibly the form of P6 are important in potentiating the process.
Mol Plant Microbe Interact 1997 Dec
PMID:Transgenic Arabidopsis lines expressing gene VI from cauliflower mosaic virus variants exhibit a range of symptom-like phenotypes and accumulate inclusion bodies. 939 Apr 24

As a first step toward elucidating the in vivo function of plant bZIP proteins and their related G-box cis elements, we have introduced a dominant negative inhibitor of G-box-dependent transcriptional activation into tobacco plants by transforming them with a truncated EmBP-1 gene (deltaEmBP) containing the DNA binding and dimerization domains under the control of the CaMV 35S promoter. Five independent lines of transgenic plants expressing deltaEmBP were identified, as demonstrated by immunodetection of the transgenic protein in leaf extracts, and the ability of the protein to bind a target G-box DNA sequence. The transgenic plants exhibited an abnormal phenotype characterized by interveinal chlorosis, growth inhibition and weakening of stems and petioles, the severity of which positively correlated with deltaEmBP expression and G-box DNA binding capability. Furthermore, development of chlorosis and growth inhibition was dependent on growth irradiance. Low light promoted the development of interveinal chlorosis and growth inhibition in the transgenic plants, whereas high light conditions led to near-complete amelioration of the abnormal phenotype. Transgenic plants under both light regimes showed signs of impaired stem and petiole function which was not observed in wild-type tobacco. RhcS gene expression was not significantly altered by deltaEmBP expression, suggesting that down-regulation of this gene was not responsible for the altered phenotype. The results suggest that G-box elements specific for the EmBP-1 class of bZIP proteins have an important developmental function in vegetative plant tissues, and that the trans-dominant negative mutant approach is a useful tool for continued in vivo functional analysis of bZIP transcription factors and their corresponding cis elements in plants.
Plant Mol Biol 1998 Nov 01
PMID:Overexpression of deltaEmBP, a truncated dominant negative version of the wheat G-box binding protein EmBP-1, alters vegetative development in transgenic tobacco. 974


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