CRIS Project Title:  
Development of Detection and Protection Technologies for Viruses and Bacteria of Major Significance to Ornamental and Nursery Crops

INTRODUCTION:  
Conducts research on important bacterial diseases of floral and woody crops. Current research interests include: developing knowledge and tools for the detection, genetic characterization and control of bacterial leaf scorch disease of woody ornamental crops caused by Xylella fastidiosa; conducting research on host range, epidemiology and control of bacterial wilt disease of geranium caused by Ralstonia solanacaerum race 3, biovar 2; and identifying alternative plant expression promoter for the development of transgenic floral crops resistant to bacterial diseases. 

PROGRESS:  
Developed a quick, simple and efficient procedure for detecting X. fastidiosa in potential insect vectors. Demonstrated for the first time the association of X. fastidiosa with a leaf-scorch disorder in Japanese beech bonsai and in black oak in the United States. Showed the causal role of X. fastidiosa in oleander leaf scorch and the presence of the disease in various locations in Texas.  Isolated strains of X. fastidiosa from porcelain berry (an invasive exotic), wild grape, and mulberry in a defined ecosystem, and determined genetic relationships to isolates from economic hosts such as grape.  Participated in the annotation and analysis of the 8X draft genome of R. solanacearum race 3, biovar 2.

PLANS:   
Develop a specific detection and identification method for woody ornamental strains of X. fastidiosa. Determine pathogenic relationships between ornamental and non-ornamental strains of X. fastidiosa. Determine the host range of R. solanacearum race 3 biovar 2 in ornamental crops, study inoculum thresholds and the effect of environmental factors on the virulence of the bacterium, and develop environmental friendly measures to control this pathogen.

PEER-REVIEWED JOURNAL PUBLICATIONS:

1993.  Romero, J., Huang, Q., Pogany, J. and Bujarski, J. J.  Characterization of defective interfering RNA components that increase symptom severity of broad bean mottle virus infections.  Virology 194:576-584. 

1994.  Pogany, J., Huang, Q., Romero, J., Nagy, P. D. and Bujarski, J. J.  Infectious transcripts from PCR-amplified broad bean mottle bromovirus cDNA clones and variable nature of leader regions in RNA 3 segment.  Journal of General Virology 75: 693-699. 

1995.   Huang, Q. and Kuc, J.  Cutin, cutinase and esterase as related to the induced systemic resistance of cucumber against Colletotrichum lagenarium.  Physiological and Molecular Plant Pathology 46: 215-226. 

1995.  Pogany, J., Romero, J., Huang, Q., Sgro, J. Y., Shang, H. Z. and Bujarski, J. J.  De novo generation of defective interfering-like RNAs in broad bean mottle bromovirus.  Virology 212: 574-586. 

1997.   Huang, Q. and Allen, C.  An exo-poly-a-D-galacturonosidase, PehB, is required for wild-type virulence of Ralstonia solanacearum.  Journal of Bacteriology 179: 7369-7378. 

2000.   Huang, Q. and Allen, C.  Polygalacturonases are required for rapid colonization and full virulence of Ralstonia solanacearum on tomato plants.  Physiological and Molecular Plant Pathology 57: 77-83. 

2001.   Huang, Q. and Hartung, J. S.  Cloning and sequence analysis of an infectious clone of Citrus yellow mosaic virus that can infect sweet orange via Agrobacterium-mediated inoculation.  Journal of General Virology 82: 2549-2558. 

2003.   Huang, Q., Li, W. and Hartung, J. S.  Association of Xylella fastidiosa with leaf scorch in Japanese beech bonsai.  Canadian Journal of Plant Pathology 25: 401-405. 

2004.   Huang, Q. and Sherald, J. L.  Isolation and phylogenetic analysis of Xylella fastidiosa from its invasive alternative host, porcelain berry.  Current Microbiology 48: 73-76. 

2004.   Huang, Q.  First report of Xylella fastidiosa associated with leaf scorch in black oak in Washington, D. C.  Plant Disease 88: 224. 

2004.   Huang, Q., Brlansky, R. H., Barnes, L., Li, W. and Hartung, J. S.  First report of oleander leaf scorch caused by Xylella fastidiosa in Texas.  Plant Disease 88: 1049. 

2006.   Gabriel, D. W., Allen, C. A., Schell, M., Denny, T., Greenberg, J., Duan, Y. P., Flores-Cruz, Z., Huang, Q., Clifford, J. M., Presting, G., Gonzalez, E. T., Reddy, J., Elphinstone, J., Swanson, J., Yao, J., Mulholand, V., Liu, L., Farmerie, W., Patnaikuni, M., Galogh, B., Norman, D., Alvarez, A., Castillo, J., Saddler, G., Walunas, T., Zhukov, A., and Mikhailova, N. Identification of open reading frames unique to a select Agent: Ralstonia solanacearum race 3, biovar 2. Molecular Plant-Microbe Interaction 19: 69-79.

2006.   Huang, Q., Bentz, J. and Sherald, J. L. Fast, easy and efficient DNA extraction and one-step PCR for the detection of Xylella fastidiosa in potential insect vectors. Journal of Plant Pathology. (In press).
       

Other Publications:

2002.   Brlansky, R. H., Howd, D. S., Huang, Q. and Hartung, J. S.  Ultrastructural aspects of citrus infected with Citrus yellow mosaic virus, p. 378-381.  In Proceedings of the 15th conference of the International Organization of Citrus Virologists.  Edited by N. Duran-Vila, R. C. Milne and J. V. da Graca.  Riverside, CA: IOCV. 

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