title: Biomechanical interaction between hyphae of two Pythium species (Oomycota) and host tissues.
abstract: Forces exerted by hyphae of the phytopathogen Pythium graminicola and mammalian pathogen Pythium insidiosum were compared with the mechanical resistance of their hosts' tissues. Hyphal apices of both species exerted a mean force of 2 microN, corresponding to mean pressures of 0.19 microN microm(-2) (or MPa) for P. graminicola, and 0.14 microN microm(-2) for P. insidiosum. Experiments with glass microprobes showed that the epidermis of grass roots resisted penetration until the pressure applied at the probe tip reached 1-12 microN microm(-2). Previously published data show that mammalian skin offers even greater resistance (10-47 microN microm(-2)). Clearly, tissue strength exceeds the pressures exerted by hyphae of these pathogens, verifying that secreted enzymes must play a critical role in reducing the resistance of plant and animal tissues. It is presumed that hyphae are sufficiently powerful to bore through any obstacles remaining after enzyme action.
authors.affiliation: Department of Botany, Miami University, Oxford, OH 45056, USA.
authors.forename: Erin
authors.initials: E
authors.lastname: MacDonald
authors.forename: Laurie
authors.initials: L
authors.lastname: Millward
authors.forename: J P
authors.initials: JP
authors.lastname: Ravishankar
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Money
mesh_terms: D001696:Biomechanical Phenomena; D006801:Humans; D025301:Hyphae / Q000254:growth & development / Q000472:pathogenicity*; D010935:Plant Diseases / Q000382:microbiology; D006109:Poaceae / Q000382:microbiology*; D011775:Pythium / Q000254:growth & development / Q000472:pathogenicity*; D013045:Species Specificity; D014908:Triticum / Q000382:microbiology*