Plantae. Rhodophyta Chlorophytes Charophytes Land Plants. II. Algal taxonomy. Division: Chlorophyta (green algae)

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1 Division: Chlorophyta (green algae) I. General Characteristics II. Distinguishing Classes III. Morphology IV. Classes in Detail II. Algal taxonomy Hierarchical system of classification: Level: suffix: example: Domain Eukaryote Group Plantae Division -phyta Chlorophyta Class -phyceae Ulvophyceae Order -ales Ulvales Family -aceae Ulvaceae Genus Ulva species fenestrata ~ 16,000 species ~ 90% freshwater 1 2 DOMAIN Groups (Kingdom) 1.Bacteria- cyanobacteria (blue green algae) 2.Archae 3.Eukaryotes 1. Alveolates- dinoflagellates Algae Glaucophytes 2. Stramenopiles- diatoms, heterokonyophyta 3. Rhizaria- unicellular amoeboids 4. Excavates- unicellular flagellates 5. Plantae- rhodophyta, chlorophyta, seagrasses 6. Amoebozoans- slimemolds Plantae Chl b, starch Rhodophyta Chlorophytes Charophytes Land Plants 7. Fungi- heterotrophs with extracellular digestion 8. Choanoflagellates- unicellular 9. Animals- multicellular heterotrophs 3 4 Adapted from Sadava

2 Phylogenetics of Chlorophyta (morphological, molecular data) I. General Green Characteristics: 5 classes: Chlorophyceae 1) Pigments:? Chl b, starch Trebouxiophyceae Ulvophyceae Chlorophyta 2) Chloroplast structure?: Prasinophyceae 3) Storage product? Encasement of egg Charophytes Charophyceae 4)? Embryo, cuticle Land plants 5 6 Classes: II. Distinguishing among classes based on: Chlorophyceae = freshwater Trebouxiophyceae = freshwater, soil and marine Ulvophyceae = marine macroalgae Prasinophyceae = primarily marine flagellates, some freshwater; modern representatives of earliest green algae Charophyceae = freshwater; all terrestrial plants are derived from Charophycean class 1. How flagella are attached/constructed: basal bodies orientation microtubule roots 2. covering: scales vs. cell wall 3. How cells divide: aspects of mitosis and cytokinesis 7 8 2

3 II. Distinguishing among classes based on: 1. How flagella are attached/constructed: -basal bodies orientation -microtubule roots - complex cellular projections used for movement - bundle of nine fused pairs of microtubule doublets surrounding two central single microtubules "9+2" Basal bodies- attachment site of the flagella - containing a microtubules 9 triplet configuration forming a hollow cylinder anterior swimming direction 9 10 : ONE per flagellum, located at base of flagellum, anchoring into cell -pairs of basal bodies may be opposite parallel clockwise counterclockwise : -under the cell membrane at point of attachment of basal bodies - may be cruciate or broadband 11 5 cruciate broad-band 12 3

4 II. Distinguishing among classes based on: 2. covering- scales vs. cell wall Scales are made of complex polysaccharides secreted from golgi prasinophyceae wall = usually cellulose Chlorophyceae, trebouxiophyceae Ulvophyceae, charophyceae II. Distinguishing among classes based on: 3. How cells divide: (aspects of mitosis and cytokinesis) open vs. closed mitotic spindle phycoplast vs. phragmoplast furrowing vs. cell plate formation in center of cell 13 closed metacentric centrioles Open -during Mt nuclear 14 envelope breaks down II. Distinguishing among classes based on: 3. How cells divide: (aspects of mitosis and cytokinesis) open vs. closed mitotic spindle phycoplast vs. phragmoplast furrowing vs. cell plate formation in center of cell II. Distinguishing among classes based on: 3. How cells divide: (aspects of mitosis and cytokinesis) open vs. closed mitotic spindle phycoplast vs. phragmoplast furrowing vs. cell plate formation in center of cell furrowing furrowing Phycoplast: microtubules parallel to dividing plane -rare in algae Phragmoplast: double microtubules perpendicular to dividing plane -land plants 15 furrowing = most algae cell plate formation = a few algae and land plants 16 4

5 III. Morphology Chlorophyta: easiest division to identify visually usually bright, grass-green color III. Morphology Chlorophyta: easiest division to identify visually usually bright, grass-green color Except - 17 photo: M organ Bond Snow algae Trentepohlia parasitic on Monterey Cypress Dunaliella 18 For classes: - any easy rules using external thallus morphology? - Prasinophyceans are all unicells, but Charophyceans Diversity in chloroplast shape: (unique to algae) napkin ring-shaped parietal cup-shaped parietal stellate (star-shaped) axial (plate-like) ribbon-like reticulate (net-like) multiple discoid Chlorophyceae Ulvophyceae Ulvophyceae

6 Some new terms: Isogamy sexual fusion between flagellated gametes that are similar in size and shape Anisogamy sexual fusion between flagellated gametes of distinctly different sizes Oogamy sexual fusion between a flagellated gamete (sperm) and non-flagellated gamete (egg) Review: Sporophyte: diploid, 2n, multicellular release spores in alternation of generations Gametophyte: hapliod, 1n, multicellular release gametes in alternation of generations 21 V. Classes in detail - Chlorophyte Diversity: 5 classes: Chlorophyceae Trebouxiophyceae Ulvophyceae Prasinophyceae Charophyceae Land plants 22 Class Charophyceae: Charophyceae Microtubule Roots: broadband : parallel 1. How flagella are attached/constructed: basal bodies orientation = parallel microtubule roots = broad band 2. covering: scales vs. cell wall = wall 3. How cells divide: spindle = open microtubule organization = phragmoplast division by = furrow or plate

7 Class Charophyceae: Genera: Desmids, Chara most closely related to terrestrial plants Algal Life Cycles Haplontic- 1N thallus, the zygote is the only diploid stage usually unicells or filaments, but sometimes colonies and more complex forms Mt N fuse freshwater N haplontic- 1N thallus, the zygote is the only diploid stage oogamous reproduction grow Me 1N spores 2N zygote dormant zygotes Class Charophyceae: Order Zygnematales Desmids 2 semi-cells that are mirror images, nucleus is in center asexual reproduction = mitosis sexual conjugation = pairing between cells movement through mucilage secretion Class Charophyceae: Order Charales Genus Chara Macroscopic Freshwater Can be partially calcified Central axis with whorls of branches at nodes Often smell of garlic Food and nursery habitat for waterfowl

8 IV. Classes in detail - Chlorophyte Diversity: Class Prasinophyceae: 5 classes: Chlorophyceae Trebouxiophyceae Ulvophyceae Prasinophyceae Charophyceae Land plants How flagella are attached/constructed: basal bodies orientation = variable microtubule roots = variable 2. covering: scales vs. cell wall = scales 3. How cells actually divide: spindle = open or closed microtubule organization = phragmoplast or phycoplast division by = furrow 30 Some Prasinophyceans Class Prasinophyceae Genus Tetraselmis Microtubule Roots: cruciate : opposite modern representatives of ancestral green (most primitive) unicellular flagellates 31 freshwater and marine one plastid with one pyrenoid mostly asexual 32 8

9 V. Classes in detail - Chlorophyte Diversity: Class Chlorophyceae: 5 classes: Chlorophyceae Trebouxiophyceae Ulvophyceae Prasinophyceae 1. How flagella are attached/constructed: basal bodies orientation = clockwise microtubule roots = cruciate 2. covering: scales vs. cell wall = wall Charophyceae Land plants How cells divide: spindle = closed microtubule organization = phycoplast division by = furrowing 34 Chlorophyceae Microtubule Roots: cruciate : clockwise Class Chlorophyceae: spp mostly freshwater unicells, colonies, coenocytes, filaments, haplontic life history- 1N thallus, the zygote is the only diploid stage, with hypnozygote = thick walled resting stage isogamous, anisogamous, and oogamous species Genera: Chlamydomonas, Volvox, Dunaliella

10 Order: Volvocales Genus: Chlamydomonas Chlamydomonas life history: Usually asexual fluid conditions Mt moist but not wet conditions Cup-shaped chloroplast, orange eyespot Scientists sequenced and mapped genome in 2003 palmelloid stage Used as a model to determine how gene expression works Use mutations to determine where genes are on chromosomes Haplontic- Sexual reproduction in unfavorable conditions Genus: Volvox Spherical colonies of ,000 cells Each colony contains a large number of somatic cells and a small number of reproductive cells Zygotes are orange (1/2) (1/2) Hypnozygote = resting stage

11 Volvox life history Genus: Dunaliella Oogamous Gonidia = specialized cells that divide to become daughter colonies Zoospore = spore with flagella Endospore = surrounds zoospore Mesospore = initially surrounds endospore + zoospore Common in salt ponds: have special ion pumps Packed with beta-carotene to protect from UV irradiance Commercial value (beta-carotene) = used for food coloring and in pharmaceuticals V. Classes in detail - Chlorophyte Diversity: 5 classes: Chlorophyceae Class Trebouxiophyceae: Trebouxiophyceae Ulvophyceae Prasinophyceae 1. How flagella are attached/constructed: basal bodies orientation = counterclockwise microtubule roots = cruciate 2. covering: scales vs. cell wall = wall Charophyceae Land plants How cells actually divide: spindle = closed; metacentric microtubule organization = phycoplast division by = furrow 44 11

12 Trebouxiophyceae Microtubule Roots: cruciate : counter- clockwise Class Trebouxiophyceae: mostly freshwater and terrestrial algae unicells, filaments, blades Genera: Chlorella, Prasiola Genus: Chlorella Genus: Prasiola - Unicellular - Endosymbiont in freshwater animals - Single, cup-shaped chloroplast - Used by Melvin Calvin to investigate carbon fixation in plants (Calvin cycle) - Marketed as a dietary supplement 47 - Diplontic- 2N thallus, the gametes are the only haploid stage - Found in ultra-high intertidal (spray zone) in areas with high guano - Nitrophilic - Thalli small (< 2cm), monostromatic blades - Individuals higher on shore produce asexual (2N) spores - Individuals lower on shore produce gametes, oogamous 48 12

13 Prasiola Life History 49 13