Shepherd, Ryan , Kroumova, Antoaneta , Wagner, George .
Phylloplane Proteins: Emerging Defenses at the Aerial Frontline.
The phylloplane, or leaf surface, is an interkingdom crossroads between plants and microorganisms. The secretion of antimicrobial biochemicals to aerial surfaces is a defensive strategy by which plants can deter potential pathogens, and defensive secondary metabolites of the phylloplane are well-documented. We identified novel antimicrobial proteins on leaf surfaces of the model plant Nicotiana tabacum that inhibited spore germination and leaf infection by the oomycete pathogen Peronospora tabacina (Plant Cell, 2005, 17: 1851-1861). These glycoproteins, termed T-phylloplanins, are biosynthesized solely in specialized epidermal structures called short glandular trichomes, and they are quickly renewed on leaf surfaces after their removal by leaf water washing. Using reverse genetics, we confirmed the antimicrobial activities of T-phylloplanins against P. tabacina, and we showed that young RNAi plants are more susceptible to disease than wild-type plants. We also recovered antimicrobial proteins from leaf surfaces of Helianthus annuus and Datura metel plants, providing further evidence that phylloplane proteins are widespread and act as first-point-of-contact deterrents to pathogen establishment (Trends in Plant Science, 2007, in press). Future research on this novel system of plant defense alludes to exciting advances in our understanding of the phylloplane, and to useful biotechnological interventions ahead.
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1 - University of California - Berkeley, Plant and Microbial Biology, 331 Koshland Hall, Berkeley, CA, 94720, U.S.A.
2 - University of Kentucky, Plant and Soil Sciences
Presentation Type: ASPB Minisymposium
Location: Continental A/Hilton
Date: Monday, July 9th, 2007
Time: 8:30 AM