Feature of ti plasmid

It is a part of Ti Plasmid which takes part intransfer and integration of T-DNA into plant chromosome.

The vir sequence consist of 8 operons which take part in different functions associated with virulence of Ti Plasmid. These are vir H, vir A, vir B, vir G, vir C, vir D, vir E, & vir F. ( vir H & vir F present occasionally).

1. FEATURES OF Ti PLASMID By KAUSHAL KUMAR SAHU Assistant Professor (Ad Hoc) Department of Biotechnology Govt. Digvijay Autonomous P. G. College Raj-Nandgaon ( C. G. )

2. SYNOPSIS INTRODUCTION Agrobacterium tumefaciens Ti plasmid CLASSIFICATION T- DNA region: Vir region: Transfer Of T-DNA To Plant Cell CONCLUSION references

3. I NTRODUCTION WHAT IS A PLASMID ?

4. Agrobacterium tumefaciens 1. Soil bacterium closely related to Rhizobium . 2. Causes crown gall disease in plants Agrobacterium  is well known for its ability to transfer  DNA between itself and plants.

5. Ti plasmid Size of the plasmid: ~250 kbp & molecular weight is 120-160 mega daltons. The plasmid has 196 genes that code for 195 proteins. Contains one or more T-DNA region. Contains regions for opine synthesis and catabolism .

6. Ti plasmid

7. CLASSIFICATION The Ti plasmids are classified into different types based on the type of opine produced by their genes. The different opines specified by pTi are octopine, nopaline, succinamopine and leucinopine. But the most commonly studied are octopine & nopaline type.

8. Fig genes carried by Nopaline & Octopine Ti Plasmid

9. T- DNA region: Portion of Ti Plasmid that is transferred to chromosomal DNA of plant is transferred –DNA/ T- DNA. Size ~ 20kbp It has a sequence for tumor induction (tum) & another sequence ocs for the production of unusual amino acid octopine. The tum region encodes for the enzymes involved in the biosynthesis of auxins & cytokinins.

10. Opine Biosynthesis 1 Within tumor tissues, the synthesis of various unusual amino acid-like compounds are directed by genes encoded on the integrated plasmid . The type of opine produced is specified by the bacterial T-DNA Opines are used by the bacteria as a carbon ( nutrient) source for growth. Opine catabolism within bacteria is mediated by genes encoded on the Ti plasmid .

11. Vir region: It is a part of Ti Plasmid which takes part intransfer and integration of T-DNA into plant chromosome. The vir sequence consist of 8 operons which take part in different functions associated with virulence of Ti Plasmid. These are vir H, vir A, vir B, vir G, vir C, vir D, vir E, & vir F. ( vir H & vir F present occasionally).

12. Fig: vir genes

13. Transfer Of T-DNA To Plant Cell

14. Ti as vectors Properties Ti is natural genetic engineers because of the following properties: They replicate autonomously without any influence of the chromosomal DNA. They carry foreign DNA segments to plant cells during infection. They have a segment called T DNA which is integrated into plant DNA. They can be transferred from bacterium to bacterium by conjugation. Transformed plants can easily be identified by tumourogenic property of the plasmid.

15. Limitations: Wild type Ti plasmids cannot be directly used as vectors because of the following limitations: Large size 2) Absence of unique restriction enzyme site 3) Opine production in transformed plant lowers the plant yield.

16. references Plant tissue culture Bhojwani & Razdan Biotechnology U. Satyanarayan Biotechnology B.D. Singh www.wikipedia.com