Dr. Ramon Jordan

Research Plant Pathologist
{Beltsville, MD}


1. Development of Detection and Protection Technologies for Viruses and Bacteria of Major Significance to Ornamental and Nursery Crops.
2. Genetic Improvement of Floral Crops for Pest, Disease, and Stress Tolerance and Ornamental Qualities.


Conducts research on the biochemical and biological nature of plant viruses, their genomes, and their gene products. Develops and utilizes serological and nucleic acid-based reagents and technologies for improved detection, differentiation and identification of new and emerging viruses; determines the genome organization of selected important ornamental viruses; and, develops methods and new strategies to confer virus resistance in plants through expression of antibody proteins or replicase-binding peptides in transgenic plants.


Research acomplishments over the last five years have included: 1) determined the full-length genome sequences of four unique viruses of geranium, Pelargonium line pattern virus, Pelargonium ringspot virus, the related Elderberry latent virus, and Pelargonium chlorotic ring pattern virus; and, based on their genome organization, proposed they be included in a new genus (Pelarspovirus) in Tombusviridae; 2) determined the full-length genome sequences of two unique US isolates of Pepino mosaic virus and the 3’ terminal portion of a third MD isolate; 3) discovered, partially characterized, cloned and sequenced the 3’ terminal portions of seven new and emerging potyviruses infecting Impatiens, Omphalodes, Spiranthes orchid, Euphorbia ‘Crown of Thorns’, and Tricyrtis ‘Toad Lily’; 4) characterized re-emerging viruses and determined new (first report) ornamental hosts for several viruses, including Bean yellow mosaic virus (BYMV) and Broad bean wilt virus (in Verbena), Lily virus X (in Tricyrtis), and Dasheen mosaic virus (in Spiranthes); 5) developed and evaluated the stable expression of recombinant single-chain (scFv) BYMV-specific and potyvirus broad-spectrum antiviral monoclonal antibodies (McAbs) as phage-displayed proteins in bacteria, and as TMV virus vector-expressed proteins in N. benthamiana; and, 6) continued collaborative research on the biological, serological and molecular characterization of, and development of detection strategies for, Plum pox virus.


Current research includes: 1) developing full length infectious DNA clones of a Pelarspovirus to initiate gene reassortment analysis to determine virus-specific sequences responsible for disease pathology; 2) develop antiviral scFv constructs from broad-spectrum potyviral protease “HC-Pro” McAbs for expression in transgenic plants as another means of viral protection; 3) develop virus-specific and broad-spectrum reactive antibodies to viral synthetic peptides and/or bacterial expression clones for improved virus detection; 4) continue research on the detection and characterization of unknown, new and emerging viruses in important ornamental plants.


Hu, J.S., Ferreria, S., Wang, M., Borth, W.B., Mink, G., and Jordan, R.L. Purification, host range, serology, and partial sequencing of Dendrobium mosaic potyvirus, a new member of the bean common mosaic virus subgroup. Phytopathology 85:542-546. 1995.

Hu, J.S., Li, H.P., Wang, M., and Jordan, R.L. Comparison of dot blot, ELISA, and RT-PCR assays for detection of two cucumber mosaic virus isolates infecting banana in Hawaii. Plant Disease 79:902-906. 1995.

Barnett, O.W., ... Jordan, R.L., et al. Family Potyviridae. In: Virus Taxonomy. Sixth Report of the International Committee on Taxonomy of Viruses. (Murphy et al; Eds), Springer-Verlag, NY. pp348-358. 1995.

Kinard, G.R., Jordan, R.L. and Hurtt, S.H. Partial characterization of Pelargonium line pattern and Pelargonium ringspot viruses. Acta Horticulture 432: 148-155. 1996.

Jordan, R.L. Cloning and Sequence Analysis of the N Gene of Several Morphologically and Serologically Distinct Isolates of Impatiens Necrotic Spot Tospovirus. Phytoparasitica24:348-349. 1996.

Gillaspie, Jr., A.G., Hopkins, M.S., Pinnow, D.L., and Jordan, R.L. Characterization of a potyvirus of the bean yellow mosaic virus subgroup in Sesbania speciosa germplasm. Plant Disease 82:807-810. 1998.

Berger, P., Barnett, O.W., ... Jordan, R.L., et al. Family Potyviridae. In: Virus Taxonomy, Classification and Nomenclature of Viruses. Seventh Report of the International Committee on Taxonomy of Viruses. (van Regenmortel et al; Eds), Academic Press, NY. pp703-724. 2000.

Jordan, R.L. Successful development of monoclonal antibodies to three carnation viruses, using an admixture of only partially purified virus preparations as immunogen, and their use in virus diagnosis. Acta Horticulture 568:177-184. 2002.

Kinard, G.R. and Jordan, R.L. Genome organization of Pelargonium chlorotic ring pattern virus: Further implications for Tombusviridae taxonomy. Acta Horticulture 568:17-28. 2002.

Jordan, R.L., Guaragna, M.A, Kinard, G.R., and Lynn, S. Detection and first report of Dasheen mosaic virus and a second potyvirus infecting the terrestrial orchid Spiranthes cernua. Acta Horticulture 568:253-260. 2002.

Gulya, T.J., Shiel, P.H., Freeman, T.F., Jordan, R.L., Isakert, T.A., and Berger, P.H. Host range and characterization of sunflower mosaic potyvirus. Phytopathology 92:694‑702. 2003.

Nemchinov,L.G., Hammond, J., Jordan, R.L., and Hammond, R.W. The complete nucleotide sequence, genome organization, and specific detection of Beet mosaic virus. Arch. Virol. 149:1201-1214. 2004.

Guaragna, M.A., Jordan, R.L. and Putnam, M. First report of Bean yellow mosaic virus (pea mosaic strain) in Verbena x hybrida. Plant Disease 88:574. 2004.

Berger, P.H, ... Jordan, R.L., et al. 2005. Potyviridae. In: Virus Taxonomy. Eighth Report of the International Committee on Taxonomy of Viruses. Springer-Verlag, NY. pp819-841. 2005.

Maroon-Lango, C.J., Guaragna, M.A., Jordan, R.L., Hammond, J., Bandla, M., and Marquardt, S. Two unique US isolates of Pepino mosaic virus from a limited source of pooled tomato tissue are distinct from a third (European-like) US isolate. Arch. Virol
150:1187-1201. 2005.

Guaragna, M.A., Ndum, O., Jordan, R.L. Detection and characterization of two previously undescribed potyviruses in the terrestrial orchid Spiranthes cernua. Acta Horticulturae (Accepted May 16, 2005). 2006.

Guaragna, M.A., Jordan, R.L. and Putnam, M. First molecular evidence of the occurrence of a pea mosaic strain of Bean yellow mosaic virus in Verbena x hybrida. Acta Horticulturae (Accepted May 16, 2005). 2006.

Jordan, R.L. and Guaragna, M.A. Detection and characterization of a new potyvirus, Impatiens flower break virus, infecting New Guinea Impatiens. Archives of Virology (submitted).

Jordan, R.L., Guaragna, M.A., Van Buren, T., Putnam, M.L. First Report of a New Potyvirus, Tricyrtis virus Y, and Lily virus X Potexvirus, in Tricyrtis formosana in the United States. Plant Disease (submitted)

Other Publications:

Jordan, R.L. and Hammond, J. Expression of viral genes and viral and antiviral proteins in transgenic plants to confer virus resistance. In: Pest Management: Biologically Based Technologies (Lumsden and Vaughn, eds.) American Chemical Society, pp. 304-312. 1994.

Hudson, D.,..., Hsu, H.T., Jordan, R.L., Kamo, K.K., et al. Tactics and strategies in solid-phase peptide synthesis: New directions, methods and applications. In: Symposium on solid-phase peptide synthesis. 1994.

Biancalana, S., Hudson, D., ..., Hsu, H.T., Jordan, R.L., Kamo, K.K., et al. Tactics and strategies in solid-phase peptide synthesis: New directions, methods and applications. In: Innovation and Perspectives in Solid Phase Synthesis: Peptides, Polypeptides and Oligonucleotides (R. Epton, ed.), Intercept Limited, Andover, England, pp. 135‑152. 1994.

Jordan, R.L. Production and application of monoclonal antibodies to plant pathogenic bacteria, Spiroplasmas, and mycoplasma-like organisms. In: Advanced Methods in Plant Pathology, CRC Press, Boca Raton, FL. 1994.

Hammond, J. and Jordan, R.L. Potyviruses. In: Encyclopedia of Plant Pathology. (Maloy and Murray, eds), John Wiley & Sons, NY, NY. pp810-817. 2001.

Hammond, J., Hsu, H.T., Huang, Q., Jordan, R.L., Kamo, K. and Pooler, M. Transgenic approaches to disease resistance in ornamental crops. Journal of Crop Improvement (Accepted May 24, 2005). 2006.

GenBank Submissions:

AF227728 Pepper mottle virus, coat protein gene

AF465545 Sunflower mosaic virus, 3’ terminal genome portion

AY038066 Elderberry latent virus, complete genome

AY038067 Pelargonium line pattern virus, complete genome

AY038068 Pelargonium ringspot virus, complete genome

AY038069 Pelargonium chlorotic ring pattern virus, complete genome

AY206394 Beet mosaic virus, complete genome

AY508411 Pepino mosaic virus, US3 strain, 3’ terminal genome portion

AY509926 Pepino mosaic virus, US1 strain, complete genome

AY509927 Pepino mosaic virus, US2 strain, complete genome

AY520092 Bean yellow mosaic virus, PMV strain, Verbena isolate, 3’ terminal portion

AY685218 Spiranthes mosaic virus 3, 3’ terminal genome portion

AY685219 Spiranthes mosaic virus 2, 3’ terminal genome portion

AY697300 Euphorbia ringspot virus, 3’ terminal genome portion

AY864849 Lily virus X, Tricyrtis formosana isolate, 3’ terminal genome portion

AY864850 Tricyrtis virus Y, 3’ terminal genome portion

AY864851 Impatiens flower break potyvirus, 3’ terminal genome portion

AY974328 Omphalodes virus Y, 3’ terminal genome portion

DQ523597 Impatiens necrotic spot virus, Schizanthus -B isolate, NP gene

DQ523598 Impatiens necrotic spot virus, Gloxinia -Igg isolate, NP gene

DQ523599 Tomato spotted wilt virus, L isolate, nucleoprotein gene

EF441726 Vallota mosaic virus, 3’ terminal genome portion

EU363481 Columbian datura virus, 3’ terminal genome portion

EU433920 Arabis mosaic virus-MD, coat protein gene