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Chlamydomonas (/ ˌ k l æ m ɪ ˈ d ɒ m ə n ə s,-d ə ˈ m oʊ-/ KLAM-ih-DOM-ə-nəs, -də-MOH-) is a genus of green algae consisting of about 150 species [2] of unicellular flagellates, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". [3]
Gonium being evolutionarily related to Chlamydomonas has a life cycle that is derivative of that of Chlamydomonas. Gonium cells grow asexually as colonies of either 4, 8 or 16 colonial cells. Cell and colony growth of Gonium is uncoupled from cell division just like Chlamydomonas and each cell within the colony divides by multiple-fission.
Zoospores may possess one or more distinct types of flagella - tinsel or "decorated", and whiplash, in various combinations. Tinsellated (straminipilous [3]) flagella have lateral filaments known as mastigonemes perpendicular to their main axis, which allow for more surface area, and disturbance of the medium, giving them the property of a rudder, that is, used for steering.
Most of the oomycetes produce two distinct types of spores. The main dispersive spores are asexual, self-motile spores called zoospores, which are capable of chemotaxis (movement toward or away from a chemical signal, such as those released by potential food sources) in surface water (including precipitation on plant surfaces). A few oomycetes ...
Reproduction occurs by the formation of zoospores with two flgaella. [3] Chlamydocapsa is a common and widespread genus in fresh waters. [3] However, it is unclear whether this genus is taxonomically valid, as it may simply be a nonmotile ("palmelloid") life stage of the genus Chlamydomonas. [4]
Zoospores are produced in wet conditions by either oospores or sporangia. [4] Phytophthora cactorum zoospores, are uninucleate, laterally biflagellate , and pear- or lemon-shaped. After being released, zoospores swim to a nearby wound on a suitable host, germinate, and enter wounds to cause a hyphal infection of the roots or crown vascular system.
Dunaliella is a single-celled, photosynthetic green alga, that is characteristic for its ability to outcompete other organisms and thrive in hypersaline environments. [1] It is mostly a marine organism, though there are a few freshwater species that tend to be more rare. [2]
Zoospores interact with the host by sensing and moving toward the nutrient gradients near the root tip and wounds of the plant. Without this means of sensing entry points there would be no secondary cycles of disease. [8] Zoospores, chlamydospores, and sporangia produce a germ tube that directly penetrates the epidermis of the plant.