Title | DNA plant viruses |
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Repository View: https://ucanr.edu/repository/a/?a=72272 Direct to File: https://ucanr.edu/repository/a/?get=72272 |
Abstract |
Not available – first paragraph follows:
A remarkably simple genetic system for study of DNA multiplication and gene expression in plants is provided by DNA plant viruses. These viruses have only a half-dozen or so genes that are believed to be regulated in the same way as other plant genes. The DNA replicates in nuclei and may be associated with nuclear proteins (histones) in the same way as plant genetic material. Thus, the virus provides a small-scale, readily manipulated model for gene expression. |
Authors |
Daubert, Stephen D. : Stephen D. Daubert, Postdoctoral Research Associate, Plant Pathology, U.C., Davis
Gardner, Richard C. : Richard C. Gardner, Principal Scientist, Calgene, Inc., Davis.
Shepherd, Robert J. : Robert J. Shepherd, Professor, U.C., Davis
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Publication Date | Aug 1, 1982 |
Date Added | Jul 17, 2009 |
Copyright | © The Regents of the University of California |
Copyright Year | 1982 |
OCR Text |
Leaves from turnip plants infected genes via crown gallwill lead to plants that re - with cauliflower mosaic virus . Leaf tain and express new characteristics . In fact , on left is infected with native , similardemonstrations of T - DNA expression virus . Those on right are wild - type in normal plant tissueshave now been accom - from plants infected with mutants plished in at least five other laboratories by insertion of 12s produced additional nucleotide pair into worldwide . the chromosome of the same virus Because the abnormal growth of crown strain . Plants infected with the gall tissues is a major obstacle to crown - gall - mutant on the right grow almost mediated plant genetics , we have also investi - as rapidly as healthy plants . gated the unusual hormone metabolism associated with the disease to determine whether it is the cause of the abnormal growth . The fact that crown gall tissues differ from nontransformed plant tissues in being one ( gene 11 ) is not essential for reproduc - able to grow on a simple nutrient medium tion , enclothement in protein , or cell - to - cell DNA plant viruses lacking auxin and cytokinin suggests that movement . Recent work at Davis indicates crown galls produce these hormones at ele - that this nonessential gene is probably in - Robert J . Shepherd vated rates . Our own studies on cytokininsin volved in insect transmission of the virus in Stephen D . Daubert a variety of crown galls indicate that these nature . These dispensible regions of the virus C . Gardner Richard tissues generally overproduce cytokinins at chromosome provide sites for insertion of 8 - to 1,600 - fold greater levels ranging from foreign DNA , which is carried into the plant than normal . The predominant cytokinins in and replicated along with the DNA of the in - A remarkably simple genetic system for crown galls have been purified and identified fecting virus . study of DNA multiplication and gene ex - as zeatin and ribosylzeatin , which are Another region of the cauliflower mosaic pression in plants is provided by DNA plant N6 - substituted derivatives of adenine and virus chromosome has been identified as viruses . These viruseshave only a half - dozen adenosine , respectively . In addition , crown being responsible for the severity of disease . or sogenesthat are believed to be regulatedin galls with extremelyhigh total cytokinin con - This region is gene VI on the physical map . the same way as other plant genes . The DNA tents contain glucose derivatives of both of The other five genes appear to have little , if replicates in nuclei and may be associated these cytokinins . any , effect on symptom induction . A single with nuclear proteins ( histones ) in the same Presumably , the hormone imbalance re - a profound effect change in gene VI can have as plant genetic material . Thus , the virus way sultingfrom T - DNA expressionin crown gall on disease expression : in one case , insertion provides a small - scale , readily manipulated cells underlies the abnormal growth we ob - of 12 base pairs at a particular location in model for gene expression . serve . We have detected genes on the Ti plas - in - gene VI almost abolished disease . Plants Viruses reproduce in living tissue by sup - mid affecting cytokinin biosynthesis by the fected with this mutant of the virus show very plying a few of their own functions , while fill - C . I . Kado has shown that pathogen , and as mild symptoms and grow at the same rate ing most of their needs by parasitizing the plasmid genes for auxin biosynthesis also ex - healthy plants . Information of this sort may a smallloop host . Each viral particle contains ist . Identifyingthese genesand their products enable the investigator to control disease ex - of nucleic acid , the genetic component , en - is a first step toward controlling them . Ulti - of the viruschromosome pression , if portions clothed in an outer shell of coat protein . The mately , we would like to have effective Ti are eventually used as a recombinant DNA protein is shed soon after the particle enters plasmid vectors that introduce desirable vector for plants . the cell , and the DNA sets about reprogram - genes into plants without also making tumors . as Cauliflower mosaic virus has been used ming the cell to manufacture virus . In carry - a vehicle to reproduce foreign DNA in plant John W Einset , Assistant Professor , Botany and ing out these changes , the virus interferes cells and to carry this foreign DNA from cell Plant Sciences , Cell Interaction Group , U.C . , so that the cell with normal cellular functions Riverside . to cell throughout the entire plant . However , becomes less well coordinated . The organism not enough foreignDNA can be inserted into as a whole is affected and shows disease the virus chromosome to bring about useful symptoms . Reductions in growth rate and transformations of plants . This limitationap - leaf puckering and yellowing are common ef - pears to be related to a low capacity of the of the DNA viruses . fects virus particle to accommodate additional One DNA plant virus , the cauliflower mo - to DNA . Assemblyof DNA and coat protein saic virus , has received more attention than form virus particles seems to be necessary the others . Its biology has been intensively before the DNA will move from cell to cell in studied during the last few years , and the the plant . It does not appear , therefore , that DNA from two strains of this virus has been the virus in its present form will be useful as a completely sequenced . At Davis , for exam - recombinant DNA vector . However , this vi - ple , an isolate has been found to have 8,031 Small , ntergen , c rus will probably play an important role in reg > on pairs of nucleotides in its circular chromo - defining the biological activity of those se - some . Nucleotides make up the language Physical map of circular chromosome of quences involved in replication and expres - cauliflowermosaic virus . Genes defined by with which genetic information is expressed . sion of DNA in plants . by nucleotide sequence are indicated of nucleotides and other infor - This sequence arrowed lines I to VI . Box indicates naturally Robert J . Shepherd , Professor , and Stephen D . mation have been used to construct a physical occurring deletion of most of region I1 Daubert , Postdoctoral Research Associate , Plant map of the virus chromosome ( see diagram ) . ( strain CM4 - 184 ) . Open triangles indicate Pathology , U.C . , Davis ; and Richard C . Gard - ner , Principal Scientist , Calgene , Inc . , Davis . three single - stranded interruptions . Of the half - dozen genes of this simple virus , 16 CALIFORNIA AGRICULTURE , AUGUST 1982
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