0.9 bya = first multicellular algae!

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1 8/12/14 Photosynthetic organisms on earth 3.45 bya = Cyanobacteria appear and introduce photosynthesis 1.5 bya = first Eukaryotes appeared (nuclear envelope and ER thought to come from invagination of plasma membrane) 0.9 bya = first multicellular algae 800 mya = earliest Chlorophyta (Green algae) mya = plants on land derived from Charophyceae 250 mya = earliest Heterokontophyta (Brown algae) 100 mya = earliest seagrasses (angiosperms) 1

2 8/12/14 Rhodophyta Characteristics 1) Pigments: 2) Chloroplast structure: 3) Storage product: s 4) Flagella: n 5) Mitosis: Division Rhodophyta - most speciose of the macroalgae > 5000 species total 98% marine Location S. Australia N. Atlantic Pacific Red Brown Green

3 8/12/14 Biogeography/Distribution - found at all latitudes - temperate / tropical = highest # of species (outnumber browns and greens) - polar = relatively few species browns and greens dominate = crustose coralline reds, to 200 m - size distribution = tropical => small filamentous plants (except calcareous) = temperate => larger fleshy species Phycobilisome Structure 3

4 8/12/14 vs. other divisions: pigments imbedded within the thylakoid membrane Rhodophyta Morphology of Cell Walls Two Main Components: 1. Cellulose = microfibrils Function: structural support 2. Phycocolliods- Mucilaginous polysaccarides = surrounds the microfibrills a. agar (agarose) b. carrageenan Function: elasticity; flexibility; prevent desiccation; and osmoregulation 4

5 8/12/14 Rhodophyta Cell Characteristics: 1. Multinucleate = one cell has multiple nuclei, # of nuclei = # of plastids 2. Polyploidy = repeated genome duplication, buffer against mutation of essential genes (endoreduplication = replication, no mitotic nuclear division) Cell Characteristics Apical cell: Uninucleate non- polyploid Multinucleate non-polyploid Uninucleate polyploid Derived cells: Uninucleate Multinucleate Uninucleate non- polyploid non- polyploid polyploid Multinucleate non- polyploid Rhodochorton Chondrus Antithamnion Griffithsia Uninucleate non- polyploid Polysiphonia Dasya 5

6 8/12/14 Pit plugs = structural support between cells - protein plugs between cells - primary pit plugs = formed during cytokinesis - secondary pit plugs = formed between non-related cells - not a real connection unlike browns, not for transport Rhodophyta Morphology - unicellular = solitary non motile cells - filamentous = chain of cells Polysiphonia - parenchymatous = undifferentiated, isodiametric cells generated by a meristem - pseudoparenchymatous = form of thallus composed of interwoven continuous filaments Rhodella Smithora 6

7 8/12/14 Polysiphonous central cell surrounded by 4 or more peri-central cells Rhodophyte Growth Reds often display growth through cell elongation New growth = not florescent Cell repair by cell fusion 7

8 8/12/14 Heterotrichous Growth filamentous growth in 2 directions = cell division Corallina Polysiphonia Porhyra Uniaxial Growth - one longitudinal central filament forming the axis Gracilariopsis Gracilaria 8

9 8/12/14 Multiaxial Growth - several longitudinal medullary filaments, each derived from an apical cell, hair formation Corallina Amphiroa Pericentral Growth - single filament divides at tip, creating new cells that elongate the filament Polysiphonia Ceramium 9

10 8/12/14 Life History - spores none - gametes none - spermatia = unflagellated male gamete; no free movement = passive dispersal by water Triphasic Life Histories :Terminology Tetrasporophyte = 2N generation from germinating carpospore Tetrasporangium = 2N cell which undergoes meiosis to form 4 tetraspores Tetraspore = N spore formed by meiosis from 2N tetrasporophyte cell release 10

11 8/12/14 Triphasic Life Histories :Terminology Female Gametophyte" Carpogonial branch (cb)= filamentous branch forming carpogonium Carpogonium (cp) = female gamete Trichogyne = extension of egg, attaches to " spermatium Male Gametophyte" Spermatangial branch = filamentous branch holding spermatangia (p) Spermatangium (s) = male reproductive structure producing spermatia Spermatia = male gamete Female trichogyne gametophyte - Polysiphonia cp cb Male gametophyte - Polysiphonia tetrasporophyte tetrasporangium tetraspore gametophyte release carpogonial branch, carpogonium, trychogyne 11

12 8/12/14 Triphasic Life Histories :Terminology Carposporophyte = one of the 2N generations (all 2N material on the female gametophyte); this is where the 2N zygote is cloned to form the carpospores Pericarp = 1N vegetative tissue surrounding carposporophyte 2N tetrasporophyte 1N gametophytes release release growth 2N 1N 2N carposporophyte on 1N female gametophyte 12

13 8/12/14 Division: Rhodophyta Class: Rhodophyceae Subclass: Bangiophycidae Florideophycidae - simple reds - unicells, filaments, parenchymatous - marine, terrestrial, freshwater - uninucleate - one stellate chloroplast per cell - pit plugs rare - biphasic life history - advanced reds - multicellular: filaments, - marine, freshwater Porphyridium - almost always multinucleate - many discoid chloroplasts - primary and secondary pit plugs - triphasic life history Bangia Porphyra Porphyra 1N gametophyte: - parenchymatous blade 2N sporophyte: - conchocelis stage - discovered in 1949 by Kathleen Drew Baker - microscopic, filamentous - lives on/in mollusk shells - perennial - Saxicolous or epiphytic - Harvested for nori 13

14 8/12/14 Division: Rhodophyta Class: Rhodophyceae Subclass: Bangiophycidae Florideophycidae - simple reds - unicells, filaments, parenchymatous - marine, terrestrial, freshwater - uninucleate - one stellate chloroplast per cell - pit plugs rare - biphasic life history - advanced reds - multicellular: filaments, - marine, freshwater - almost always multinucleate - many discoid chloroplasts - primary and secondary pit plugs - triphasic life history Order: Ceramiales Ceratium Polysiphonia Polysiphonia - prominent trichoblasts = leave scars after they fall off - polysiphonous - saxicolous or ephiphytic - fully or partially corticated - uniaxial 14

15 8/12/14 Order: Gigartinales Mazzaella Chondrus crispus Mastocarpus - proteinaceous cuticle layering produces light interference patterns - uni- or multiaxial filamentous or parenchymatous - Mastocarpus smells like chlorine - Chondrus crispus - often have epiphytes or facilitate settlement of other algae Order: Corallinales Corallina Lithophyllum (encrusting) Bossiella - cell walls impregnated with CaCO3 - isomorphic alternation of generation - reproductive structures in conceptacles - multiaxial growth - ecological importance: stabilize reefs, invert settlement 15

16 8/12/14 Human Uses of Rhodophyta 1) Food - nori (Porphyra) 2) Phycocolliods = from polysaccharides of cell walls - thickeners, stabilizers, gels - two important phycocolliods: Carrageenan found in Chondrus, Gigartina, Eucheuma and Kappaphycus Agar found in Gelidium,Gracelaria, Pterocladia, and Ahnfeltia 16