Note on Higher Fungi

                                                                                           

                                                            GENERAL BOTANY  Lecture Note - Higher Fungi

IV (Continued from last time) - Types of fungi

(Continued from last time) - Kingdom Fungi (Mycota): characteristics - Hyphae & mycelium

                A.            Phylum  Zygomycota (the zygote sits around zzzzzzzzzzz!)

                --------------------------------- THE HIGHER FUNGI START HERE --------------------------------------------

                B.            Phylum Ascomycota - it has to ASK for a partner

                C.            Phylum Basidiomycota "B" - Puffballs, bracket fungi, mushrooms

                                - Elaborate structures referred to as basidiocarps; distinguishing characteristic – the four nuclei (after meiosis) are carried on separate stalks called sterigmata; cell undergoing meiosis and producing spores are called basidium and the spores are called basidiospores

                                1.             (Class) Homobasidiomycetes - elaborate basidiocarps

                                                a)             Cell walls contain chitin, hyphae are septate, sexual reproduction is highly developed (asexual also occurs)

                                                b)             Sexual reproduction - conjugation (fusion) of hyphae produces a dikaryon (N + N) [the dikaryon can last up to centuries]

                                                                1)            Homothallic - conjugation with self or others

                                                                2)            Heterothallic - conjugation only with others

                                                                3)            N + N mycellium divides and maintains N + N condition

                                                                4)            N + N phase gives rise to spore bearing body called basidiocarp (the mushroom, puff ball, etc.)

                                                                5)            Stalk = stipe, cap (umbrella) = pileus, underside contents = hyphae with large number of basidia , gills = fleshy-looking plates radiated out from the stalk

                                                                6)            In basidia, nuclei fuse and immediately undergo meiosis to make haploid cells

                                                                                a))           Sterigmata form at the tip of basidium and haploid nuclei escape to make spores (up to a million a minute for several days!)

                                                                7)            Order Agaricales:  some are poisonous, some aren't

                                                                8)            Variations include gills, pores, and brackets (conk)

                                2.             (Class) Heterobasidiomycetes - basidiocarps not very elaborate

                                                a)             Heteroecious - have more than one host (i.e., rust requires barberry & wheat)

                                                                1)            Mycellium develops in tissue of host to make pustules called spermagonia - these get cut off to make spermata

                                                                2)            Spermatia go by wind to receptive hyphae - an N + N mycelium results (note genetic diversity)

                                                                3)            Mycelium forms pustules called aecia which form N + N aeciospores

                                                                4)            Aeciospores escape and invade wheat (through stomata)

                                                                5)            In wheat, N + N uredospores form in uredia (and invade wheat)

                                                                6)            During winter, teliospores are produced by mycelium

                                                                7)            Fusion occurs in teliospores during winter and meiosis leads to new haploid cells that put out a short hypha in the spring

                                                b)             Autoecious - have only one host

                                                                1)            Haploid stuff, conjugation, N + N mycelium, N + N spores formed, over winter nuclei fuse, spring meiosis, haploid basidiospores

                                                c)             Examples:  rust and smut

                D.            Phylum Deuteromycota - Fungi Imperfecti - "Retarded dude"

                                1.             No known reproductive cycle - can not be considered ascomycetes or basidiomycetes

                                2.             Examples include Penicillium and Aspergillus

V.            Lichens - algae and fungi

                A.            Symbiotic - algae provides food; fungus provides moisture, shelter, & minerals