1. Tobacco mosaic virus
M.M. Hernandez

2. Tobacco mosaic virus TMV
Genus Tobamovirus
15 members
naked, rigid rod,
+ unsegmented ss RNA
No family assignation by ICTV

3. STRUCTURAL FEATURES OF TMV
CAPSID
30 nm
Helical symmetry
RNA genome
18 nm
2 nm
NC protein
Images:P. Sforza, 2001

4. TMV genome organization
6,395 nt
30 K
MT-Hel
UAG (leaky)
183K
Replicase RdRp
tRNAhis
17.6 K
Movement MP
Capsid CP
5’ cap
126 K

5. Host: Nicotiana tabaccum (Solanaceous ) & other 9 plant families susceptible too

6. Disease:Mosaic (calico)

7. Mosaic disease on Tobacco leaf

8. Necrosis
Chlorosis
Stunting
Mosaic disease: significant losses in yield & $ value

9. TMV Life cycle 5’
cap
Host Rb
a) Virus entry trough abrasions on plant tissue. Inside cell associates with ER
b) spontaneous release of few capsid (CP) subunits 5' end of genome is uncovered
c) Host ribosome attaches to viral RNA, moves down displacing more CP units
…/…
Modification of a diagram from: L. Stannard, Department of Medical Microbiology, U. of Cape Town

10. TMV Life cycle (cont.) 5’
d) Ribosome meets start codon, translates first two proteins (126K ,183 K) while uncoating continues
“co-traslational disassembly”
e) 126 K ( MET-Hel) & 183 K ( RdRp) use viral RNA as template to make full length complementary neg. strand RNA
…/…
Modification of a diagram from: L. Stannard, Department of Medical Microbiology, U. of Cape Town

11. TMV Life cycle (cont.)
RdRp
+ Strand (genome)
Neg. strand
f) Neg. RNA strand used by viral replicase (RdPp/MET-Hel ) as template for +RNA
g) Also, neg. RNA strand has internal promoters used by replicase to make mRNA for 30K protein (MP) and 17.5 K (CP)
promoters
Transcription by RdRp
MP mRNA
CP mRNA

12. TMV Life cycle (cont.)
h) MP combines with viral +RNA to move it into new plant cells through plasmodesmata

13. TMV Life cycle (cont.)
i) Accumulation of +RNA & CP proteins stimulates assembly of progeny virions
Viral RNA interacts with discs
CP units self assemble into discs
Electrostatic interaction stabilizes structure into helix
M. Olvera de la Cruz

14. TMV Life cycle (cont.)
j) massive TMR replication occur in the X-bodies (viroplasmas)
Szecsi et al. 1999
Hamacher et al. 2003

15. TMV Life cycle (cont.)
k) Virus will remain in plant tissue and sap until delivered to a new plant host usually by mechanical means

16. TMV diagnosis Symptoms E.M. & Serology RT-PCR & RFLP
Letschert et al. 2002
HTTP;//BAKERLAB.BERKELEY.EDU/?IMG=1

17. Current Research on TMV
Improving diagnostic techniques
Characterization of MP and viral movement through plant
Characterization of the Helicase & RdRp

18. Questions?

19. REFERENCES
Agrios G. N Plant Pathology Third Edition. Academic Press, Inc. San Diego
pp:
Ashby J., E. Boutant, M. Seemanpillai, A. Sambade, C. Ritzenthaler, M. Heinlein Tobacco Mosaic Virus Movement Protein Functions as a structural Microtubule-Associated Protein. Journal of Virology. 80(17):
Bos L Plant Viruses Unique and intriguing pathogens. Backhuys Publishers Leiden
Dovas C., K. Efthimious, N. I. Katis Generic detection and differentiation of tobamoviruses by a spot nested RT-PCR-RFLP using dI-contining primers along with homologous dG-containing primers. Journal of Virological Methods. 117:
Goelet P., Lomonossoff G. P., Blutler P. JG, Akam M. E., Gait M. J., and Karn J., Nucleotide sequence of the tobacco mosaic virus RNA. Proc. Natl. Acad. Sci. U.S.A. 79:
Goregaoker S. P. and J. N. Culver Oligomerization and Activity of the Helicase Domain of the Tobacco Mosaic Virus 126- and 183-Kilodalton Replicase Proteins. Journal of Virology. 77 (6):
Hirashima K. and Y. Watanabe Tobamovirus Replicase Coding Region is Involved in Cell-to-Cell Movement. Journal of Virology. 75 (18)
Hirashima K. and Y. Watanabe RNA Helicase Doamin of Tobamovirus Replicase Executes Cell-to-Cell Movement Possibly through Collaboration with its Nonconserved Region. Journal of Virology. 77 (22)
Horst K.R.(reviser), 2001 Westcott=s Plant Disease Handbook Six Edition. Kluwer Academic Plublishers.Boston pp:
Jacobi V., G.D. Bachand, R.C. Hamelin and J.D. Castello Development of a multiplex immunocapture RT-PCR assay for detection and differentiation of tomato and tobacco mosaic tobamoviruses. Journal of Virological Methods 74 (2):
International Committee on Taxonomy of Viruses (ICTV) ICTVdB Virus Descriptions Tobacco mosaic virus (vulgare strain; ssp. NC82 strain). Retrieved November 22, 2002, from:
Kawakami F. M., R.W. Kim, R.N. Beachy Domains of tobacco mosaic virus movement protein essential for its membrane association. Journal of General Virology 87(9):

20. Khan J. A. and J. Dijkstra editors, 2002
Khan J. A. and J. Dijkstra editors, Plant Viruses as Molecular Pathogens Food Product Press 7 An Imprint of the Haworth Press Inc. New York
Lazarowitz S. G., Plant Viruses In: Fundamental Virology Fourth Edition. Knipe D. and P.M. Howley Editors. Lippincott Williams & Wilkins, Philadelphia. pp:
Lesemann D.-E., S. Winters Detection and specific identification of tobamoviruses in horticultural crops by immunoelectron microscopical methods (IEM) and ELISA. Mitteilungender Biologischen Bundesanstalt fur Land-und Forstwirtschaft 357
Letschert B., A Gunter, L. Dietrich-Eckhardt, P. Willingmann, C. Heinze., Detection and differentiation of serologically cross-reacting tobamoviruses of economical importance by RT-PCR and RT-PCR-RFLP. Journal of Virological Methods 106:1-10
Lucas G. B. , C.L. Campbell, and L.T. Lucas, Introduction to Plant Diseases Identification and Management. The AVI Publishing Company, Inc. Westport Connecticut. pp
Martin J.H. , W.H. Leonard and D. L. Stamp 1976 Principles of Field Crop Production Third Edition MacMills Publishing Co., INC. London
Matthews R.E.F., Fundamentals of Plant Virology Academic Press Inc San Diego
Matthews R.E.F., 1999 Plant Virology Third Edition. Academic Press Inc San Diego. pp:
Osman T. A. M., and K.W. Buck Identification of a Region of the Tobacco Mosaic Virus 126- and 183-Kilodalton Replication Proteins Which bind Specifically to the Viral 3'-Terminal tRNA-like Structure. Journal of Virology 77(16 )
Padmanadban M.S., Goregaoker S.P., S. Golem, H. Shiferaw, and J. N. Culver Interaction of the Tobacco Mosaic Virus Replicase Protein with the Aux/IAA Protein PAP1/IAA26 Is associated with Disease Development. Journal of Virology. 79 (4)
Sacristan S., J. M. Malpica, A. Fraile, F. Garcia-Arenal Estimation of Population Bottlenecks during Systemic Movement of Tobacco Mosaic Virus in Tobacco Plants. Journal of Virology 77(18)
Seemanpillai M., R. Elamawi, C. Ritzenthhaler, M. Heinlein Challenging the Role of Microtubules in Tobacco Mosaic Virus Movement by Drug Treatment is Disputable. Journal of Virology 80(13):
Torok V.A. and J.W. Randles Tobacco mosaic virus RNA as an internal control for duplex RT-PCR assay of pea germaplsm. Australian Plant Pathology 30:
Zaitlin M., Tobamovirus in: The Spriger Index of Viruses. Tidona C. A. and G. Darai Editors. Springer-Verlag, Berlin

27. Salt (M) Acidity 1. Solution of TMV Capsid Proteins
2. Add ssTMV+ RNA (assembly infective virus): Electrostatic attraction stabilizes viral assembly.
1. Solution of TMV Capsid Proteins
Electrostatic repulsion inhibits
+ protein +protein aggregation.
Salt (M)
ZRNA= -1/mer
3. Sphere-like (icosahedral) RNA virus
(Tsuruta et al)
Acidity
4. Capsid + Hole (density ≈ RNA crystal) self-assembles from capsid protein + viral RNA solution