Disease Cycle
White rust is an obligate parasite. This means it needs a living host to grow and reproduce. The Albuginaceae reproduce by producing both sexual spores (called oospores) and asexual spores (called sporangia) in a many-stage (polycyclic) disease cycle.
The thick-walled oospores are the main overwintering structures, but the mycelium can also survive in conditions where all the plant material is not destroyed during the winter. In the spring the oospores germinate and produce sporangia (s. sporangium) on short stalks called sporangiophores that become so tightly packed within the leaf that they rupture the epidermis and are consequently spread by the wind. The liberated sporangia in turn can either germinate directly with a germ tube or begin to produce biflagellate motile zoospores. These zoospores then swim in a film of water to a suitable site and each one produces a germ tube - like that of the sporangium - that penetrates the stoma. When the oomycete has successfully invaded the host plant, it grows and continues to reproduce.
Read more about this topic: Albugo
Famous quotes containing the words disease and/or cycle:
“It is useless to check the vain dunce who has caught the mania of scribbling, whether prose or poetry, canzonets or criticisms,—let such a one go on till the disease exhausts itself. Opposition like water, thrown on burning oil, but increases the evil, because a person of weak judgment will seldom listen to reason, but become obstinate under reproof.”
—Sarah Josepha Buell Hale 1788–1879, U.S. novelist, poet and women’s magazine editor. American Ladies Magazine, pp. 36-40 (December 1828)
“Only mediocrities progress. An artist revolves in a cycle of masterpieces, the first of which is no less perfect than the last.”
—Oscar Wilde (1854–1900)