Plant transformation vector: Difference between revisions

Revision as of 21:08, 24 May 2025

Latest revision as of 14:41, 22 July 2025

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* [[Insertional mutagenesis]] (but not lethal for the plant cell – as the organism is diploid)

* Transformation DNA fed to rodents ends up in their [[phagocyte]]s and rarely in other cells. Specifically, this refers to bacterial and [[M13 bacteriophage|M13]] DNA. (This preferential accumulation in phagocytes is thought to be real and not a detection artefact since these DNA sequences are thought to provoke [[phagocytosis]].) However, no [[gene expression]] is known to have resulted, and this is not thought to be possible.<ref name="Goldstein-et-al-2005">{{cite journal | last1=Goldstein | first1=Daniel A. | last2=Tinland | first2=Bruno | last3=Gilbertson | first3=Lawrence A. | last4=Staub | first4=J.M. | last5=Bannon | first5=G.A. | last6=Goodman | first6=R.E. | last7=McCoy | first7=R.L. | last8=Silvanovich | first8=A. | title=Human safety and genetically modified plants: a review of antibiotic resistance markers and future transformation selection technologies | journal=[[Journal of Applied Microbiology]] | publisher=[[Society for Applied Microbiology]] ([[Wiley Publishing|Wiley]]) | volume=99 | issue=1 | year=2005 | issn=1364-5072 | doi=10.1111/j.1365-2672.2005.02595.x | pages=7–23| pmid=15960661 | doi-access= | s2cid=40454719 }}</ref><ref name="Lemaux-2008">{{cite journal | last=Lemaux | first=Peggy G. | title=Genetically Engineered Plants and Foods: A Scientist's Analysis of the Issues (Part I) | journal=[[Annual Review of Plant Biology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=59 | issue=1 | year=2008 | issn=1543-5008 | doi=10.1146/annurev.arplant.58.032806.103840 | pages=771–812 | pmid=18284373 | bibcode=2008AnRPB..59..771L }}</ref>

==Plasmid selection==

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T-DNA contains two types of genes: the [[Oncogene|oncogenic genes]], encoding for [[Enzyme|enzymes]] involved in the synthesis of [[Auxin|auxins]] and [[Cytokinin|cytokinins]] and responsible for [[tumor]] formation, and the genes encoding for the synthesis of [[Opine|opines]]. These compounds, produced by the condensation between [[Amino acid|amino acids]] and sugars, are synthesized and excreted by the crown gall cells, and they are consumed by A. tumefaciens as carbon and nitrogen sources.

The genes involved in opine [[catabolism]], T-DNA transfer from the bacterium to the plant cell and [[Bacterial conjugation|bacterium-bacterium plasmid conjugative transfer]] are located outside the T-DNA.<ref name=":0">{{Cite journal |last1=Hooykaas |first1=Paul J. J. |last2=Schilperoort |first2=Rob A. |date=1992-05-01 |title=Agrobacterium and plant genetic engineering |url=https://doi.org/10.1007/BF00015604 |journal=Plant Molecular Biology |language=en |volume=19 |issue=1 |pages=15–38 |doi=10.1007/BF00015604 |pmid=1600167 |bibcode=1992PMolB..19...15H |s2cid=36172990 |issn=1573-5028|url-access=subscription }}</ref><ref name=":1">{{Cite journal |last1=Zupan |first1=J. R. |last2=Zambryski |first2=P. |date=1995-04-01 |title=Transfer of T-DNA from Agrobacterium to the Plant Cell |url=https://doi.org/10.1104/pp.107.4.1041 |journal=Plant Physiology |volume=107 |issue=4 |pages=1041–1047 |doi=10.1104/pp.107.4.1041 |issn=0032-0889 |pmc=157234 |pmid=7770515}}</ref> The T-DNA fragment is flanked by 25-bp direct repeats, which act as a cis-element signal for the transfer apparatus. The process of T-DNA transfer is mediated by the cooperative action of [[Protein|proteins]] encoded by genes determined in the Ti plasmid virulence region (vir genes) and in the bacterial chromosome. The Ti plasmid also contains the genes for opine catabolism produced by the crown gall cells and regions for conjugative transfer and for its own integrity and stability. The 30 kb virulence (vir) region is a [[regulon]] organized in six [[Operon|operons]] essential for the T-DNA transfer (virA, virB, virD, and virG) or for the increasing of transfer efficiency (virC and virE).<ref name=":0" /><ref name=":1" /><ref>{{Cite journal |last1=Jeon |first1=Geoung-A |last2=Eum |first2=Jin-seong |last3=Sim |first3=Woong Seop |date=1998-02-01 |title=The Role of Inverted Repeat (IR) Sequence of the virE Gene Expression in Agrobacterium tumefaciens pTiA6. |journal=Molecules and Cells |volume=8 |issue=1 |pages=49–53 |doi=10.1016/S1016-8478(23)13391-7 |pmid=9571631 |issn=1016-8478|doi-access=free }}</ref> Several chromosomal-determined genetic elements have shown their functional role in the attachment of ''A. tumefaciens'' to the plant cell and bacterial colonization. The loci chvA and chvB are involved in the synthesis and excretion of the b -1,2 [[glucan]],<ref>{{Cite journal |last1=Cangelosi |first1=G A |last2=Martinetti |first2=G |last3=Leigh |first3=J A |last4=Lee |first4=C C |last5=Theines |first5=C |last6=Nester |first6=E W |date=March 1989 |title=Role for [corrected] Agrobacterium tumefaciens ChvA protein in export of beta-1,2-glucan |journal=Journal of Bacteriology |language=en |volume=171 |issue=3 |pages=1609–1615 |doi=10.1128/jb.171.3.1609-1615.1989 |issn=0021-9193 |pmc=209788 |pmid=2921245}}</ref> the {{not a typo|chvE}} required for the sugar enhancement of vir [[Gene induction|genes induction]] and [[Bacterial chemotaxis - general|bacterial chemotaxis]].<ref>{{Cite journal |last1=Ankenbauer |first1=R G |last2=Nester |first2=E W |date=November 1990 |title=Sugar-mediated induction of Agrobacterium tumefaciens virulence genes: structural specificity and activities of monosaccharides |journal=Journal of Bacteriology |language=en |volume=172 |issue=11 |pages=6442–6446 |doi=10.1128/jb.172.11.6442-6446.1990 |issn=0021-9193 |pmc=526831 |pmid=2121715}}</ref><ref>{{Cite journal |last1=Cangelosi |first1=G A |last2=Ankenbauer |first2=R G |last3=Nester |first3=E W |date=September 1990 |title=Sugars induce the Agrobacterium virulence genes through a periplasmic binding protein and a transmembrane signal protein. |journal=Proceedings of the National Academy of Sciences |language=en |volume=87 |issue=17 |pages=6708–6712 |doi=10.1073/pnas.87.17.6708 |doi-access=free |issn=0027-8424 |pmc=54606 |pmid=2118656|bibcode=1990PNAS...87.6708C }}</ref><ref name=":2">{{Citation |last1=Cangelosi |first1=Gerard A. |title=Bacterial Genetic Systems |date=1991 |pages=384–397 |url=https://doi.org/10.1016/0076-6879(91)04020-o |access-date=2024-03-09 |publisher=Elsevier |doi=10.1016/0076-6879(91)04020-o |last2=Abest |first2=Elaine |last3=Martinetti |first3=Gladys |last4=Nester |first4=Eugene W.|chapter=Genetic Analysis of Agrobacterium |series=Methods in Enzymology |volume=204 |pmid=1658565 |isbn=978-0-12-182105-0 |url-access=subscription }}</ref> The cell locus is responsible for the synthesis of [[cellulose]] fibrils.<ref>{{Cite journal |last=Matthysse |first=A G |date=May 1983 |title=Role of bacterial cellulose fibrils in Agrobacterium tumefaciens infection |journal=Journal of Bacteriology |language=en |volume=154 |issue=2 |pages=906–915 |doi=10.1128/jb.154.2.906-915.1983 |issn=0021-9193 |pmc=217544 |pmid=6302086}}</ref> The {{not a typo|pscA (exoC)}} locus is involved in the synthesis of both cyclic glucan and acid [[Glycan|succinoglycan]].<ref>{{Cite journal |last1=Cangelosi |first1=G A |last2=Hung |first2=L |last3=Puvanesarajah |first3=V |last4=Stacey |first4=G |last5=Ozga |first5=D A |last6=Leigh |first6=J A |last7=Nester |first7=E W |date=May 1987 |title=Common loci for Agrobacterium tumefaciens and Rhizobium meliloti exopolysaccharide synthesis and their roles in plant interactions |journal=Journal of Bacteriology |language=en |volume=169 |issue=5 |pages=2086–2091 |doi=10.1128/jb.169.5.2086-2091.1987 |issn=0021-9193 |pmc=212098 |pmid=3571162}}</ref><ref name=":2" /> The att locus is involved in the cell [[Surface protein|surface proteins]].<ref>{{Cite journal |last=Matthysse |first=Ann G. |date=October 1987 |title=Effect of Plasmid pSa and of Auxin on Attachment of Agrobacterium tumefaciens to Carrot Cells |journal=Applied and Environmental Microbiology |language=en |volume=53 |issue=10 |pages=2574–2582 |doi=10.1128/aem.53.10.2574-2582.1987 |issn=0099-2240 |pmc=204148 |pmid=16347473|bibcode=1987ApEnM..53.2574M }}</ref>

==References==