Fungi and Plant Diversity: Study Guide for Exam 3 (Kingdom Mycota & Plantae)

Kingdom Mycota (Fungi)

Fungal Cell Structure and Components

• Chitin: A strong, flexible polysaccharide forming the main component of fungal cell walls. Provides structural support and protection.

• Ergosterol: A sterol unique to fungal cell membranes, functionally similar to cholesterol in animal cells. Targeted by many antifungal drugs.

Fungal Body Organization

• Hyphae: Thread-like filaments that make up the body (mycelium) of multicellular fungi. Can be septate (divided by cross-walls called septa) or coenocytic (lacking septa).

• Mycelium: A mass of hyphae forming the main vegetative part of a fungus. Usually haploid (n) in most life stages.

• Septa: Cross-walls within hyphae that may be perforated, allowing cytoplasm and organelles to move between cells.

• Exoenzymes: Enzymes secreted by fungi to digest food outside their bodies, allowing absorption of nutrients.

Fungal Nutrition and Symbiosis

• Saprotrophs: Fungi that decompose dead organic matter.

• Parasites: Fungi that feed on living hosts, often causing disease.

• Symbiosis: Close association between fungi and other organisms, including mutualism (both benefit), commensalism, and parasitism.

• Haustoria: Specialized hyphae that penetrate host tissues to extract nutrients (common in parasitic fungi).

• Mycorrhiza: Mutualistic association between fungi and plant roots. Types include:

  • Ectomycorrhizae: Fungi form a sheath (mantle) around roots and a network (Hartig net) between root cells.

  • Endomycorrhizae (Arbuscular): Fungi penetrate root cells, forming arbuscules for nutrient exchange.

• Endophytes: Fungi living inside plant tissues without causing harm, often providing benefits like increased resistance to stress or herbivory.

Fungal Reproduction

• Asexual Reproduction:

  • Fragmentation: Hyphae break into pieces, each growing into a new individual.

  • Budding: Common in yeasts; a new cell forms as a bud on the parent.

  • Spores: Produced by mitosis; dispersed to form new fungi.

• Sexual Reproduction:

  • Homothallic: Fungi that can mate with themselves (self-fertile).

  • Heterothallic: Require two genetically different individuals to mate.

  • Plasmogamy: Fusion of cytoplasm from two parent mycelia.

  • Karyogamy: Fusion of nuclei, resulting in a diploid zygote.

Fungal Ecology and Interactions

• Lichens: Symbiotic association between a fungus and a photosynthetic partner (alga or cyanobacterium). Example of obligate symbiosis (partners cannot live separately).

• Anthrobotrys oligospora: A predatory fungus that traps nematodes.

• Claviceps purpurea: Causes ergot disease in grains; produces toxic alkaloids.

• Botrytis cinerea: Causes grey rot in plants.

Fungal Diseases and Toxins

• Mycosis: Fungal infection in animals or humans.

  • Cutaneous mycosis: Affects skin (e.g., "ringworm", Batrachochytrium dendrobatidis in amphibians, Pseudogymnoascus destructans in bats).

  • Systemic mycosis: Affects internal organs (e.g., Coccidioides spp.).

• Mycotoxicosis: Poisoning from fungal toxins (e.g., aflatoxins from Aspergillus spp.).

• Mycetismus: Poisoning from eating toxic mushrooms.

Fungi as Biopesticides

• Beauveria bassiana and Metarhizium anisopliae: Fungi used as biological control agents against insect pests.

Key Concepts in Fungal Biology

• Fungal phyla are classified based on reproductive structures and molecular data.

• Deuteromycetes are no longer a separate phylum due to advances in genetic classification.

• Fungi are more closely related to animals than plants (e.g., chitin, glycogen storage, flagellated cells).

• Fungi thrive in moist, nutrient-rich environments but can tolerate harsh conditions due to spore production and metabolic diversity.

• Mycorrhizal and endophytic relationships are crucial for plant health and ecosystem function.

• Fungal infections are difficult to treat due to similarities between fungal and animal cells (e.g., ergosterol vs. cholesterol).

• Biopesticides offer environmentally friendly pest control but may have limitations (e.g., specificity, persistence).

Kingdom Plantae – Seedless Plants

Life Cycles and Reproduction

• Tolerance: Ability of nonvascular plants to survive desiccation.

• Alternation of Generations: Life cycle alternating between multicellular haploid (gametophyte) and diploid (sporophyte) stages.

• Haplontic: Life cycle dominated by haploid stage.

• Diplontic: Life cycle dominated by diploid stage.

• Haplodiplontic: Both haploid and diploid stages are multicellular (seen in plants).

• Sporangia: Structures where spores are produced.

• Sporocytes: Diploid cells in sporangia that undergo meiosis to produce spores.

• Sporopollenin: Durable polymer in spore walls, prevents desiccation.

• Gametangia: Structures producing gametes; antheridium (male), archegonium (female).

• Apical meristem: Region of active cell division at plant tips, enabling growth.

Plant Structure and Classification

• Vascular tissue: Specialized for transport; includes xylem (water/minerals) and phloem (sugars).

• Tracheophytes: Vascular plants; Non-tracheophytes: Nonvascular plants.

• Tracheids: Water-conducting cells in xylem.

• Herbaceous: Non-woody plants.

Nonvascular Plants (Bryophytes)

• General characteristics: Lack vascular tissue, small size, require moist environments.

• Structures: Thallus (body), stem, rhizoid (root-like, not true roots).

• Phylum Marchantiophyta (liverworts): Lobate (flat) vs. leafy forms, gametophores (gamete-bearing structures), elaters (spore dispersal), gemmae (asexual reproduction).

• Phylum Anthocerotophyta (hornworts): Have stomata for gas exchange.

• Phylum Bryophyta (true mosses): Protonema (early gametophyte), foot (attaches sporophyte), calyptra (protective cap), operculum (spore release), Sphagnum mosses (peat formation).

Vascular Seedless Plants

• General characteristics: Have vascular tissue, true roots, and leaves.

• Roots: Anchor plant, absorb water/nutrients.

• Leaves: Photosynthesis; microphylls (single vein), megaphylls (branched veins).

• Phylum Lycophyta: Strobili (cone-like structures), Lycopodium (club mosses).

• Phylum Monilophyta: Includes horsetail ferns (Equisetum, with rhizomes), whisk ferns (Psilotum nudum), and true ferns (with fronds, adventitious organs, crozier or fiddlehead).

• Sori: Clusters of sporangia on fern fronds.

• Dichotomous: Branching into two equal parts.

Key Concepts in Seedless Plant Evolution

• Colonization of land by plants began ~470 million years ago.

• Advantages of land: More sunlight, CO2, fewer herbivores, nutrient-rich soil.

• Challenges: Desiccation, support, reproduction without water, nutrient transport.

• Major derived traits: Alternation of generations, multicellular dependent embryos, walled spores, apical meristems.

• Trend: Gametophyte dominance in nonvascular plants; sporophyte dominance increases in vascular plants.

• Mosses (especially Sphagnum) are ecologically important for carbon storage and as peat.

Kingdom Plantae – Seed Plants

Seed Plant Innovations

• Progymnosperms: Extinct group, ancestors of seed plants.

• Heterospory: Production of two types of spores—megaspores (female) and microspores (male).

• Megasporangia: Produce megaspores; Microsporangia: Produce microspores.

• Pollination: Transfer of pollen to ovule.

• Ovules: Structure containing female gametophyte and egg; protected by integument. Ovule develops into a seed after fertilization.

• Pollen: Male gametophyte; allows fertilization without water.

• Seeds: Consist of embryo, food supply, and seed coat (three layers: integument, nutritive tissue, embryo).

• Flowers: Reproductive structures of angiosperms; facilitate pollination.

• Fruit: Mature ovary; aids in seed dispersal.

Gymnosperms

• General characteristics: "Naked seeds" (not enclosed in fruit), mostly wind-pollinated.

• Phyla:

  • Coniferophyta: Conifers (pines, firs, spruces).

  • Cycadophyta: Cycads (palm-like, tropical).

  • Gingkophyta: Ginkgo biloba, only living species.

  • Gnetophyta: Includes Ephedra (source of ephedrine), Gnetum gnemon, Welwitschia mirabilis.

• Monoecious: Both male and female cones on same plant; dioecious: Separate male and female plants.

• Evergreen: Retain leaves year-round; deciduous: Shed leaves seasonally.

• Endemic: Species native to a specific region.

Angiosperms (Phylum Anthophyta)

• General characteristics: Seeds enclosed in fruit, flowers, double fertilization.

• Groups: Basal angiosperms, monocots (one cotyledon), eudicots (two cotyledons).

• Double fertilization: One sperm fertilizes egg (embryo), another fuses with two nuclei to form endosperm (nutritive tissue).

• Radicle: Embryonic root.

• Cotyledon: Seed leaf; stores or absorbs food for embryo.

• Herbivory: Consumption of plant tissues by animals; plants have evolved defenses.

Key Concepts in Seed Plant Evolution

• Permian period: Drier climate favored seed plants over seedless plants.

• Major derived traits: Reduced gametophytes, heterospory, ovules, pollen, seeds.

• Pollen and seeds allowed reproduction independent of water and greater dispersal.

• Flowers and fruit increased reproductive success and seed dispersal.

• Gymnosperm life cycle: Dominant sporophyte, wind-pollinated, seeds not enclosed in fruit.

• Angiosperm life cycle: Flowers, double fertilization, seeds enclosed in fruit.

• Monocots vs. eudicots: Differ in number of cotyledons, leaf venation, vascular arrangement, root systems, and floral parts.

• Seed plants are essential for food, medicine, building materials, and ecosystem services.

Feature	Monocots	Eudicots
Cotyledons	One	Two
Leaf venation	Parallel	Net-like
Vascular bundles	Scattered	Ring
Root system	Fibrous	Taproot
Floral parts	Multiples of 3	Multiples of 4 or 5

Example:

• Wheat is a monocot; oak tree is a eudicot.

Additional info: The above content expands on the study guide terms and key concepts, providing definitions, examples, and context for exam preparation.