title: Dynamic rearrangement of F-actin organization triggered by host-specific plant signal is linked to morphogenesis of Aphanomyces cochlioides zoospores.
abstract: Cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone), a root releasing host-specific plant signal triggers chemotaxis and subsequent morphological changes in pathogenic Aphanomyces cochlioides zoospores before host penetration. The present study illustrates time-course changing patterns of cytoskeletal filamentous actin (F-actin) organization in the zoospores of A. cochlioides during rapid morphological changes (encystment and germination) after exposure to cochliophilin A. Confocal laser scanning microscopic analysis revealed that F-actin microfilaments remained concentrated at ventral groove and diffusely distributed in peripheral cytoplasm of the zoospore. These microfilaments dramatically rearranged and changed into granular F-actin plaques interconnected with fine arrays during encystment. A large patch of actin arrays accumulated at one pole of the cystospores just before germination. Then the actin plaques moved to the emerging germ tube where a distinct cap of microfilaments was seen at the tip of the emerging hypha. Zoospores treated with an inhibitor of F-actin polymerization, latrunculin B or motility halting and regeneration inducing compound nicotinamide, displayed different patterns of F-actin in both zoospores and cystospores than those obtained by the induction of cochliophilin A. Collectively, these results indicate that the host-specific plant signal cochliophilin A triggers a dynamic polymerization/depolymerization of F-actin in pathogenic A. cochlioides zoospores during early events of plant-peronosporomycete interactions.
authors.affiliation: Graduate School of Agriculture, Hokkaido University, Sapporo, Japan. tofazzalislam@yahoo.com
authors.forename: Md Tofazzal
authors.initials: MT
authors.lastname: Islam
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism / Q000648:ultrastructure; D020418:Algal Proteins / Q000378:metabolism / Q000648:ultrastructure; D044744:Aphanomyces / Q000502:physiology / Q000648:ultrastructure; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D047309:Flavones / Q000378:metabolism; D009024:Morphogenesis; D010944:Plants / Q000378:metabolism / Q000382:microbiology; D015398:Signal Transduction / Q000502:physiology*; D053778:Thiazolidines / Q000378:metabolism
chemical_list: D000199:Actins; D020418:Algal Proteins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D047309:Flavones; D053778:Thiazolidines; C494663:cochliophilin A; C037068:latrunculin B