Submitted to: Plant Biology
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2004
Publication Date: July 28, 2004
Citation: Muhitch, M.J., Savary, B.J., Nunez, A., Wicklow, D.T., Kendra, D.F., Alessandro, R.T., Shatters, R.G. 2004. Identification of citrus leaf proteins that inhibit the growth of the maize pathogen Fusarium verticillioides in vitro. Plant Biology. Technical Abstract: Fusarium verticillioides is a maize pathogen that causes stalk, root, and cob rot, but more importantly also produces mycotoxins that contaminate the grain and reduce its market value. We are seeking to increase the resistance of maize to F. verticillioides through genetic engineering using novel antifungal proteins from unrelated plant species that are not susceptible to this pathogen. Toward this end, we have mined citrus EST libraries for genes that are homologues of a known group of small MW antifungal proteins (Shatters, et al. Gene 326; 77-86, 2004). In silico mining of 36,295 publicly available citrus EST sequences (http://harvest.ucr.edu/) resulted in the identification of 33 EST sequences representing five unigenes encoding proteins with homology to defensins or snakins, known antifungal proteins. We are now isolating low molecular weight cell-wall associated proteins from grapefruit (Citrus x paradisi Macfad.) and trifoliate orange (Poncirus trifoliata) leaves and determining their antifungal activities against F. verticillioides. Candidate proteins are being purified by multidimensional chromatography, and MALDI-TOF/TOF MS and LCQ DECA mass spectroscopy analyses are being used for peptide mass fingerprinting and amino acid sequence determination. Details for the isolation and identification of new citrus defensins will be presented at the meeting.