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Ultrastructure of Aphanomyces cochlioides zoospores and changes during their developmental transitions triggered by the host‐specific flavone cochliophilin A
Author(s) -
Tofazzal Islam M.
Publication year - 2010
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.200900301
Subject(s) - zoospore , flagellum , biology , ultrastructure , basal body , vesicle , microbiology and biotechnology , botany , spore , biochemistry , membrane , gene
Aphanomyces cochlioides is a serious damping‐off causing pathogen of sugar beet, spinach and some other members of Chenopodiaceae and Amaranthaceae. The biflagellated motile zoospores of the pathogen locate their host roots by perceiving the host‐specific flavone cochliophilin A (5‐hydroxy‐6,7‐methylenedioxyflavone), transiently modify into cystospores that germinate prior to penetration. This study for the first time illustrated ultrastructure of the zoospores and morphological modification during their developmental transitions triggered by cochliophilin A using transmission electron microscopy (TEM). TEM revealed that zoospores had two heterokont flagella inserted laterally into a ventral groove of their body where each is attached to a kinetosome. In the cross sections of flagellar axonemes, two single and nine peripheral microtubules in doublets were clearly observed. Mitochondria, the Golgi complexes, finger print vesicles, and vesicles with striated electron opaque inclusion and vesicles containing a granular cortex and center were also detected. The latter vesicles disappeared and two flagella were shed when zoospores converted to spherical cystsopores. The shape, size and number of mitochondria were dynamically changed during the encystment of zoospores presumably through fission and fusion processes. The dynamics of mitochondria observed in this study indicated its distinct role in the signal transduction pathway of the zoospore encystment. This study also revealed the transformation of shape of nuclei from pyriform in zoospores to spherical in cystospores and lanceolate in the hyphae. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)