Sensitive detection as well as knowledge of the genetic variability of pest/host populations form essential parts of any integrated pest/disease management strategy. The Molecular Diagnostics Group develops nucleic acid-based diagnostic tools for sensitive detection and discrimination of plant pathogens and their vectors. In addition, molecular marker methods are being employed to identify host resistance genes and the origin of the blood meals of tsetse flies.

The Molecular Diagnostics Group carries out strategic and applied nucleic-acid based research to provide tools for the detection of pathogens or pests, and to allow epidemiological questions to be answered.

• Development of DNA- or RNA-based methods for pathogen diagnosis
• Adaptation of such techniques to their use in less sophisticated laboratories
• Use of DNA sequencing and genetic fingerprinting techniques to assess pathogen, host or pest variability
• Evaluation of nucleic acid-based detection methods and comparison to isolation and serological methods
• Training and formal teaching on molecular diagnostic methods, including (RT)-PCR, RAPD- and AFLP- fingerprinting
• Supervision of research students to PhD level

Projects

Development of sensitive PCR-based tests to detect and differentiate sub-groups of Ralstonia solanacearum, causal agent of bacterial wilt.

 

Development of PCR tests for Mycosphaerella fijiensis, causal agent of black sigatoka of banana.

 

Genetic variability of M. fijiensis, and within the Rhizoctonia rice sheath disease complex.

 

Detection of corn stunt spiroplasma and maize bushy stunt phytoplasma.

 

Identification of the phytoplasma causing Gliricidia sepium little leaf.

 

Genetic variability of yam viruses, particularly yam potyviruses.

 

Development of room temperature stable RT-PCR kits.

 

Genetic variability of geminiviruses on tomato and cassava, and of their vector Bemisia tabaci.

 

Use of DNA microsatellites to study the feeding behaviour of haematophagous Diptera.

 

Use of AFLPs to identify molecular markers in groundnut for resistance to groundnut rosette virus and its vector Aphis craccivora.

Publications

Boa, ER., Kenyon, L., Jordan and T. Gliricidia little-leaf disease symptom development and assesment. Plant Pathology

 

Singh, U.D., Rutherford, M, Turner, H.C. Banniza, S., Jahanson, A., Davies, D., Bridges, P. and Buddie, A.(2000) Components of the Rhizoctonia sheath disease complex of rice in India.

 

Thwaites, R., Eden-Green, S. and Black, R. Diseases Caused by Bacteria. In: Jones, D (Ed.) Diseases of Banana and Plantain. In press.

 

Nath, P.D., Kenyon, L., Bartolme, V.I., Mclaren, G. and Azzam, O. (2000). Simple serological assays for detecting rice tungro viruses. Food and Agricultural Immunology 12: 139-153.

 

Thwaites, R., Mansfield, J., Eden-Green, S. and Seal, S. 1999. RAPD and rep-PCR fingerprinting of vascular bacterial pathogens of Musa spp. Plant Pathology 48: 121-128.

 

Thwaites R., Mansfield J., Eden-Green S. and Seal S. (1999). Polymerase Chain Reaction Fingerprinting of Vascular Bacterial Pathogens of Musa spp. Plant Pathology 48: 121-128.

 

Seal S, Taghavi M., Fegan N., Hayward A.C. and Fegan M. (1999). Determination of Ralstonia (Pseudomonas) solanacearum rDNA subgroup by PCR tests. Plant Pathology 48: 115-120

 

Alicai T., Fenby N.S., Gibson R.W., Adipala E., Vetten H.J., Foster G.D. and Seal S.E. (1999) Occurrence of two serotypes of sweet potato chlorotic stunt virus in East Africa and their associated differences in coat protein and HSP70 homologue gene sequences. Plant Pathology 48: 718-726.

 

Black, R., Seal S., Abubakar Z., Nono-Womdim, R., Swai I. (1999) Wilt pathogens of Solanaceae in Tanzania: Clavibacter michiganensis subsp. michiganensis, Pseudomonas corrugata, and Ralstonia solanacearum. Plant Disease 83: 1070

 

Black, R., Abubakar, Z., Seal., S. & Phiri, N. (1998). Adaptation of technology for diagnosis and detection of Ralstonia solanacearum in Malawi and Tanzania. In: Prior P, Allen C, Elphinstone J, eds. Bacterial wilt disease, molecular and ecological aspects. Springer-Verlag/INRA editions: 111-115.

 

Fenby N.S., S. Seal, R.W. Gibson, G.D. Foster (1998). RNA extraction from virus diseased sweet potato for RT-PCR analysis. Molecular Biotechnology 10: 187-190

 

Gibson RW, Mpembe I, Alicai T, Carey EE, Mwanga ROM, Seal SE, & Vetten HJ (1998). Symptoms, aetiology and serological analysis of sweet potato virus disease in Uganda. Plant Pathology 47: 95-102.

 

Henríquez N.P., Kenyon,L. Quiroz, L. (1998). Corn stunt complex mollicutes in Belize. Plant Disease 83: 77

 

Johanson, A., Turner, H. C., McKay, G. J., Brown, A.E. (1998), 'A PCR-based method to distinguish fungi of the rice sheath-blight complex, Rhizoctonia solani, R Oryzae and R oryzae-sativae', FEMS Microbiology Letters 162: 289-294.

 

Kenyon, L., Harrison, N. A., Richardson, P. A. (1998). Gliricidia Little Leaf Disease in Costa Rica. Plant Disease 83: 77

 

Kenyon, L., Harrison, N.A., Ashbourne, G.R., Boa, E,R,, Richardson, P.A. (1998), 'Detection of a pigeon pea witches'-brown-related phytoplasma in trees of Gliricidia sepium affected by little-leaf disease in Central America', Plant Pathology 47 (5): 671-680.

 

Kenyon, L., Henríquez, N.P., Harrison, N.A. (1998). Diagnosis and detection of phytoplasma diseases of tropical crops. Proceedings British Crop Protection Conference Pests and Diseases 1998 3: 779- 787

 

Seal S. (1998). Chair's perspective on Diagnosis of Ralstonia solanacearum. In: Prior P, Allen C, Elphinstone J, eds. Bacterial wilt disease, molecular and ecological aspects. Springer-Verlag/INRA editions 101-102.

 

Seal S. (1998). Molecular methods for detection and discrimination of Ralstonia solanacearum. In: Prior P, Allen C, Elphinstone J, eds. Bacterial wilt disease, molecular and ecological aspects. Springer-Verlag/INRA editions 103-109.

 

Seal S. and Coates D. (1998) "Detection and quantification of plant viruses by PCR". In Methods in Molecular Biology 81: "Plant Virology protocols: From Virus Isolation to Transgenic Resistance" (eds. G. Foster and S. Taylor), Humana Press Inc, Totowa, NJ. 469-485.

 

Smith, M.C., Holt, J., Kenyon, L., Foot, C. (1998). Quantitative epidemiology of banana bunchy top virus disease and its control. Plant Pathology 47: 177-187

 

Thwaites, R., Eden-Green, S., Mansfield, J. and Seal. S. 1998. Studies on the molecular basis for pathogenicity and host specificity in strains of Ralstonia solanacearum pathogenic to banana. pp. 192-194 In: Prior, P., Allen, C. and Elphinstone, J. (Eds.) Bacterial Wilt Disease: Molecular and Ecological Aspects. Springer, Heidelberg / INRA, Paris

 

Thwaites, R., Eden-Green, S., Mansfield, J., Seal, S. (1998). Studies on the molecular basis for pathogenicity and host specficity in strains of Ralstonia solanacearum pathogenic to banana. In: Bacterial Wilt Disease (ed. Prior, Allen & Elphinstone) 192-194. Berlin: Springer.

 

Turner, H. (1998), 'Molecular variability of the rice leaf scald pathogen Monographella albscens', Poster and abstract in Proceedings of the 7th International Congress of Plant Pathology.

 

Turner, H., Banniza, S., Johanson, A., Davies, D., Bridge, P.D., Rutherford, M.A., Singh, U.D. (1998), 'Investigation of the Rhizoctonia sheath disease complex in rice', Proceedings of the 7th International Congress of Plant Pathology.

 

Turner, H.C. & Black, R. (1998). Rice leaf scald: pathogen biology and diversity. In: Major Fungal Diseases of Rice (eds. S. Sreenivasprasad & R. Johnson). Amsterdam: Kluwer (in press).

 

Kenyon, L., Brown, M.; Khonje, P. (1997) First report of Banana Bunchytop Virus in Malawi. Plant Disease 81: 1096.

 

Badge, J.L., Adams M, Antoniw J., Brunt A.A., Carson R., Dagless E., Kashiwazaki, Karamagioli M., Lock S., Phillips S., Seal S., Turner R., Foster G.D. (1997). PCR primers for the rapid identification of carlaviruses, bymoviruses and macluraviruses. Journal of Experimental Botany 48: 18.

 

Fenby NS, Foster GD, Seal SE, and Gibson RW. (1997) The whitefly-borne component of sweet potato virus disease in East Africa. Journal of Experimental Botany 48: 19-20.

 

Moore E., Kruger A., Hauben L., Seal S., Daniels M., De Baere R., De Wachter R., Timmis K., Swings J. (1997) 16S rRNA gene sequence analyses and inter- and intrageneric relationships of Xanthomonas species and Stenotrophomonas maltophilia. FEMS Microbiology Letters 151: 145-153.

 

Mumford R. A., and Seal SE (1997) Rapid single-tube immunocapture RT-PCR for the detection of two yam potyviruses. Journal of Virological Methods 69: 73-79

 

Seal S. (1997) Cost analysis and detection of bacteria and phytoplasmas in plant tissue cultures by PCR. p123-130 In Pathogen and Microbial Contamination Management in micropropagation (A.C. Cassells ed.). 12: Developments in Plant Pathology. Kluwer Academic press 370 pp.

 

Stevenson, P. C., Turner, H. C. & Haware, M. P. (1997) Phytoalexin accumulation in the roots of chickpea (Cicer arietinum L.) seedlings associated with resistance to Fusarium wilt (Fusarium oxysporum f. sp. ciceri). Physiological and Molecular Plant Pathology 50: 167-178.

 

Black R., Seal S. and Robinson-Smith A. (1996) Detection and identification of Pseudomonas solanacearum and other plant-pathogenic bacteria in less-developed countries. Proceedings of the BCPC conference on diagnostics in crop production, Warwick, 1-3 April 1996 (Ed. G. Marshall)

 

Badge J., Brunt A., Carson R., Dagless E., Karamagioli, M., Phillips, S., Seal S., Turner R. & Foster G.D. (1996). A carlavirus-specific PCR primer and partial nucleotide sequence confirms cowpea mild mottle virus as a whitefly-transmitted carlavirus. European Journal of Plant Pathology 102: 305-310.

 

Kenyon, L. (1996). Virus Diseases In: Groundnuts. 2nd. edn. Pest Control Series. NRI, Chatham, UK. (ISBN 0 85954 391 9)

 

Seal SE. (1996) Molecular diagnosis of plant pathogenic prokaryotes in the tropics. Pages 56-570, In Proceedings of the Brighton Crop protection Conference on Pests and Diseases, Brighton, 18-21 November 1996.