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1.
H. Levesque P. Delepelaire P. Rouzé J. Slightom D. Tepfer 《Plant molecular biology》1988,11(6):731-744
Analysis of published sequences for Ri TL-DNA (root-inducing left-hand transferred DNA) of Agrobacterium rhizogenes revealed several unsuspected structural features. First, Ri TL-DNA genes are redundant. Using redundancy as a criterion, three regions (left, middle and right) were discerned. The left one, ORFs (open reading frames) 1–7, contains no detectable redundancy. In the middle region a highly diverged gene family was detected in ORFs 8, 11, 12, 13 and 14. The right region contains an apparently recent duplication (ORF 15 =18+17). We interpret the phenomenon of redundancy, particularly in the central region that encodes the transformed phenotype, to be an adaptation that ensures function in a variety of host species. Comparison of Ri TL-DNA and Ti T-DNAs from Agrobacterium tumefaciens revealed common structures, unpredicted by previous nucleic acid hybridization studies. Ri TL-DNA ORF 8 is a diverged Ti T-DNA tms1. Both Agrobacterium genes consist of a member of the diverged gene family detected in the central part of the Ri TL-DNA, but fused to a sequence similar to iaaM of Pseudomonas savastonoi. Other members of this gene family were found scattered throughout Ti T-DNA. We argue that the central region of Ri and the part of Ti T-DNA including ORFs 5–10 evolved from a common ancestor. We present the hypothesis that the gene family encodes functions that alter developmental plasticity in higher plants. 相似文献
2.
M. J. J. van Haaren J. T. Pronk R. A. Schilperoort P. J. J. Hooykaas 《Plant molecular biology》1987,8(1):95-104
Summary Border fragments of the octopine Ti-plasmid were tested for their ability to restore tumorigenicity of an avirulent mutant carrying a deleted right border. It was found that neither introduction of left border fragments nor that of small right border fragments at the position of the deletion resulted in a complete restoration of oncogenicity. However, insertion of a larger right border fragment in the deletion mutant gave fully oncogenic strains. In the latter case sequences to the right side of the right border repeat were found to be responsible for a complete restoration of oncogenicity. Also a left border repeat inserted together with this enhancer sequence fully restored the oncogenicity of the deletion mutant. The enhancer-sequence on itself was not able to mediate the transfer of the T-region to the plant cell. Border fragments inserted in inverted orientation in the deletion mutant were able to mediate the transfer of the T-region to the plant cell, but at a reduced frequency. 相似文献
3.
Cardarelli M Mariotti D Pomponi M Spanò L Capone I Costantino P 《Molecular & general genetics : MGG》1987,209(3):475-480
Summary Segments of the TL-DNA of the agropine type Ri plasmid pRi 1855 encompassing single and groups of open-reading frames were cloned in the Ti plasmid-derived binary vector system Bin 19. Leaf disc infections on Nicotiana tabacum led to transformed plants, some of which showed typical hairy root phenotypes, such as the wrinkled leaf morphology, excessive and partially non geotropic root systems and the ability of leaf explants to differentiate roots in a hormone-free culture medium. Particularly interestingly, most of these traits were shown by plants transformed with a TL-DNA segment encompassing the single ORF 11, corresponding to the rolB locus. Hairy root can be induced by this latter T-DNA segment on wounded stems of tobacco plants; hairy root induction on carrot discs requires, on the contrary, a more complex complement of TL-DNA genes.Abbreviations YMB
yeast mannitol broth
- MS
Murashige and Skoog medium
- 6-BAP
6-benzylaminopurine
- NAA
naphthalene acetic acid
- Km
kanamycin
- Cb
carbenicillin 相似文献
4.
L. Jouanin P. Guerche N. Pamboukdjian C. Tourneur F. Casse Delbart J. Tourneur 《Molecular & general genetics : MGG》1987,206(3):387-392
Summary The structure of the T-DNA in Ri-transformed plants of Brassica napus, Nicotiana plumbaginifolia and Nicotiana tabacum was analysed. All the plants studied present a particular phenotype with wrinkled leaves. The T-DNA is composed of two parts: TL and TR. The size of the TL-DNA (19–20 kb) seems to be almost constant, except in N. tabacum where it is shorter. The TR-DNA can be absent, and its size varies from about 5–28 kb, with two predominant lengths. The smaller size does not include the region homologous to the tms genes of the pTi T-DNA. The copy number varies from one to four copies per plant genome. TL and TR-DNA are not always present in the same copy number, but in some cases are linked together. 相似文献
5.
6.
Timothy J. Strabala Sebastian Y. Bednarek Gregory Bertoni Richard M. Amasino 《Molecular & general genetics : MGG》1989,216(2-3):388-394
Summary A 1.9 kb clone of the T-DNA region of the Agrobacterium tumefaciens Ti plasmid Bo542 which exhibited homology to the isopentenyl transferase (ipt) locus of pTiA6 was identified by low stringency DNA hybridization. Introduction of this segment of pTiBo542 DNA into cells of Nicotiana tabacum or N. glauca caused tumor formation in vivo, and allowed hormone independent growth in vitro. Furthermore, this DNA segment complemented ipt mutant strains of A. tumefaciens, restoring their ability to cause tumors on Kalanchöe leaves and tomato stems. The complete DNA sequence of this segment has been determined, revealing an open reading frame homologous to other known Agrobacterium ipt genes. 相似文献
7.
I. Capone L. Spanò M. Cardarelli D. Bellincampi A. Petit P. Costantino 《Plant molecular biology》1989,13(1):43-52
Single and multiple infections of carrot discs were carried out with Agrobacterium strains harbouring different segments of pRi1855 TL-DNA cloned in the binary vector Bin 19 and with a strain carrying the TR-DNA from the same Ri plasmid. Roots induced by the various co-inoculations were cultured and their growth patterns were followed. Abundant roots could be induced by TL-DNA rol genes A, B and C as a single insert (rolA+B+C) and by rolB alone provided an extended segment beyond its 5 noncoding region was included in the construction. A depression of rooting capability was caused by the inclusion of rolC together with rolB (rolB+C). In all cases co-inoculation with the Agrobacterium carrying TR-DNA-borne auxin genes was necessary for root induction since none of the rol constructions was in itself capable of eliciting any response; an exceeding majority of these roots were however shown to contain rol genes but no TR-DNA. Rooting was also elicited if rol constructions were co-inoculated with a strain carrying TL-DNA genes 13 and 14 (ORF13+14) instead of the TR-DNA strain. These roots were shown to contain both rol genes and ORF13+14. Striking differences in growth properties were shown by roots containing different complements of TL-DNA genes. Typical hairy root traits, high growth rate, branching and, most noticeably, absence of geotropism, were shown by roots containing rolB alone, while roots with rolA+B+C were geotropic as normal carrot roots. Hairy root traits were conferred to rolA+B+C roots by the concomitant presence of ORF13+14 and by the addition of auxin to the culture medium. A model is presented which attempts to rationalize the growth patterns by assigning interplaying roles to the various TL-DNA genes involved. 相似文献
8.
In this article it is shown that the T-DNA of Agrobacterium tumefaciens contains besides the well-known cyt and aux genes another gene with an oncogenic effect in plants. The gene in question is called 6b and causes the formation of small tumors in plant species such as Nicotiana glauca and Kalanchoe tubiflora. 相似文献
9.
Brian A. McGaw Roger Horgan Jim K. Heald George J. Wullems Rob A. Schilperoort 《Planta》1988,176(2):230-234
The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5-monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with 15N- and 2H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N6-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.Abbreviations IAA
indole-3-acetic acid
- SIM
selected ion monitoring
- Z
zeatin
- [7G]Z
zeatin-7-glucoside
- [9R]Z
zeatin-9-riboside
- [9R-5P]Z
zeatin riboside-5-monophosphate 相似文献
10.
Vidadi M. Yusibov Pak Chun II Viacheslav M. Andrianov Eleonora S. Piruzian 《Plant molecular biology》1991,17(4):825-836
The tumour-inducing T-DNA gene 4 (T-cyt gene) of the nopaline Ti plasmid pTiC58 was cloned and introduced into tobacco cells by leaf disc transformation using Agrobacterium plasmid vectors. Tobacco shoots exposed to elevated cytokinin levels were unable to develop roots and lacked apical dominance. Using exogenously applied phytohormone manipulations we were able to regenerate morphologically normal transgenic tobacco plants which differed in endogenous cytokinin levels from normal untransformed plants. Although T-cyt gene mRNA levels, as revealed by dot-blot hybridization data, in these rooting plants were only about half those in primary transformed shoots the total amount of cytokinins was much lower than in crown gall tissue or cytokinin-type transformed shoots as reported by others. Nevertheless the cytokinin content in T-cyt plants was about 3 times greater than in control tobacco plants.Elevated cytokinin levels have been shown to change the expression of several plant genes, including some nuclear genes encoding chloroplast proteins. Our results show that the mRNA levels of chloroplast rbcL gene increase in cytokinin-type transgenic tobacco plants as compared with untransformed plants. Data obtained suggest that T-cyt transgenic plants are a good model for studying plant gene activity in different parts of the plant under endogenous cytokinin stress. 相似文献