Assistant Professor
Molecular Phytopathology
( e-mail
(610) 330-5655 voice
(610) 330-5705 FAX

Investigations in my laboratory focus on the interactions of plants and fungal and oomycete pathogens at the molecular level. Three projects are in progress: analysis and determination of the role of cell wall-degrading enzymes and inhibitors of plant defense proteins in pathogenicity, cloning and characterization of plant genes conferring resistance to fungal and oomycete diseases, and molecular characterization of races of Fusarium oxysporum, Phytophthora infestans and P. sojae found in Pennsylvania.

Project 1

Genes encoding cell wall-degrading enzymes and inhibitors of plant defense proteins constitute excellent candidates for insertional mutagenesis studies aimed at determining their precise role in the pathogenicity process. In addition, advances in genome sequencing of three species of the genus Phytophthora and three species of the genus Fusarium will facilitate the use of microarray analysis and other recently developed technologies, such as laser-capture microdissection, to identify and characterize transcription factors belonging to the cAMP/PKA, MAP kinase and glycerol signal transduction pathways involved in regulating the fungal penetration and colonization of the host plant. Together, these molecular, genomic and bioinformatic approaches can be used to elucidate the microbial pathogenicity mechanisms and understand how fungi and oomycetes can overcome the morphological, biochemical and physiological mechanisms of defense in various parts of the plant.

Project 2

Concomitantly with my studies on fungal pathogenicity, I am interested in pursuing investigations focusing on the search for plant genes conferring resistance to fungal and oomycete diseases. In my current research on potato plants I have identified several genes that appear to be involved in resistance to Phytophthora infestans race 9, and I am very interested in advancing these investigations. The significance of this research is compounded by the fact that both mating types of P. infestans have been found in the United States, making the emergence of new races by sexual recombination a very likely event. Such an increased genetic variability in the pathogen almost always renders traditional disease management less efficient. However, the use of resistance genes, introduced by molecular approaches, may successfully complement the current control measures.

Project 3

A third project of utmost importance is the molecular characterization of races of Fusarium oxysporum, some of which are among the most important mycotoxin producers, and of Phytophthora infestans and P. sojae found in Pennsylvania. Determining the pathogens’ genetic diversity is a critical step that would augment basic studies on pathogenicity. PCR amplification and sequencing of the internal transcribed spacers (ITS) 1 and 2 could be used to aid in isolate identification and race classification of F. oxysporum, P. infestans, and P. sojae.

If you are interested in working in my lab, please do not hesitate to contact me.

Representative Publications:

  • Tyler, B. et al. 2006. Phytophthora genome sequences uncover evolutionary origins and mechanisms of pathogenesis: genome sequences of the soybean pathogen Phytophthora sojae and the sudden oak death pathogen Phytophthora ramorum reveal a photosynthetic past and recent massive expansion and diversification of potential pathogenicity gene families. Science. Accepted for publication.
  • Costanzo, S., M.D. Ospina-Giraldo, K. Deahl, C.J Baker, and R.W. Jones. 2006. Gene duplication event in family 12 glycosyl hydrolase from Phytophthora spp. Fungal Genet. and Biol. In press.
  • Jones, R.W., M.D. Ospina-Giraldo, and K. Deahl. 2006. Gene silencing indicates a role for a potato endoglucanase inhibitor protein in B-0767-2 germplasm resistance to late blight. Am. J. Potato Res. 83: 41-46.
  • Rauyaree, P., M.D. Ospina-Giraldo, S. Kang, R. Bhat, K. Subbarao, S. Grant, and K. Dobinson. 2005. Mutations in VMK1, a mitogen-activated protein kinase gene, affect microsclerotia formation and pathogenicity in Verticillium dahliae. Curr. Genet. 48: 109-116.
  • Jones, R.W., M. Ospina-Giraldo, and T. Clemente. 2004. A prosystemin-antimicrobial-peptide fusion reduces tomato late blight lesion expansion. Molecular Breeding. 14: 83-89.
  • Ospina-Giraldo, M.D., Simko, I., and Jones, R.W. 2004. Characterization of an R1-like gene family from a potato differential resistant to Phytophthora infestans race 9. Twenty-first meeting of the Mid-Atlantic Plant Molecular Biology Society. Laurel, MD.
  • Ospina-Giraldo, M.D. and R. Jones. 2003. Characterization of the glucose-6-phosphate isomerase gene in Phytophthora infestans reveals the presence of multiple alleles. Fungal Genet. Biol. 40: 197-206.
  • Ospina-Giraldo, M.D., E. Mullins and S. Kang. 2003. Loss of function of the Fusarium oxysporum SNF1 gene reduces virulence on cabbage and Arabidopsis. Curr. Genet. 44: 49-57.