Introduction to Algae Lecture Notes PDF

BIOL1020 Diversity of Life I The Plant Kingdom  Learning Objectives o Define plants o Evaluation of the embryophytes (land plants) o Diversity and evolution of the algae  PLANTS CHARADES! https://www.dreamstime.com/rest-relax-enjoy-live-motivational-text-rest-relax-enjoy-li...

BIOL1020 Diversity of Life I The Plant Kingdom  Learning Objectives o Define plants o Evaluation of the embryophytes (land plants) o Diversity and evolution of the algae  PLANTS CHARADES! https://www.dreamstime.com/rest-relax-enjoy-live-motivational-text-rest-relax-enjoy-live-motivational-inspirational-quotes-words-colorful-paper-blurred- image109941226  What is a Plant? Many types and variations – Hard to define specifically while excluding non plants Historically defined as organisms that possessed photosynthesis, cell walls, spores, and sedentary behavior – This includes land plants – However, this also includes all the “algae” – It may be better to define plants in evolutionary sense Some photosynthetic organisms are not closely related to each other  What is a Plant? Green leaves, stems, roots, flowers and seeds? – Gymnosperms? – Ferns? – Cacti and succulents? Algae  Bryophytes Mosses Liverworts  Pteridophytes Horsetails Ferns Fern Allies Club Mosses Gymnosperms Cycads Conifers  Flowering Plants Smallest and largest flowers Lemna - duckweed Rafflesia Graham et al. (2006) Plants are Photoautotrophs Mozo Pty Ltd  Plants Are Photoautotrophic Autotrophs produce organic compounds from simple inorganic compounds – Food and energy? Photoautotrophs covert light energy into chemical energy – Inputs: carbon dioxide + water + light – Outputs: glucose and oxygen – 6CO2 + 6H2O → C6H12O6 + 6O2  Plants Are Photoautotrophic Exception example Psilotum - Whisk (reduced) ferns – Subterranean – Non photosynthetic – Symbiotic relationship with mycorrhizae fungi Mauseth 2017  Plants Use Cheap Building Materials Animal cells must duplicate protoplasm to grow – Cytoplasm and organelles Plant cells use vacuoles to expand – Organelles with single membrane (tonoplast) – Store water and salts Young plant cells have multiple vacuoles – Expand and merge into one central vacuole – Can expand rapidly driving cell growth  Plants Use Cheap Building Materials Flowers open and expand petals – Occurs via enlargement of vacuoles – No new cells Plant cells still synthesise proteins, organelles etc. – Otherwise, plant would become almost pure water. Plants Synchronise Lifecycle with Environment Non mobile – Venus fly trap and tumble weed? Unable to migrate to escape harsh conditions Must be able to tolerate seasonal changes – Flooding – Drought – Wildfires – Cold – etc Plants Synchronise Lifecycle with Environment Annual, biennial, perennial – Annual plants grow, reproduce and die in one year (or growing season) e.g., Anethum graveolens (Dill) – Biennial plants grow across 2 years, reproducing in the second e.g., Daucus carota subsp. Sativus (Carrot) Bulbs, roots, rhizomes – This is often influenced by conditions at a location may vary from place to place e.g., Brassica oleracea (Kale) in tropics Frosts in higher latitudes Reproduction before harsh conditions) or giving offspring improved survival chance – Winter Plants Synchronise Lifecycle with Environment Perennial plants live more than 2 years Deciduous plants vs evergreen – Abscission (loss) of leaves when no longer beneficial Must be able to tolerate seasonal changes – Drought – Cold Spondias mombin (Hog plum) vs Annona squamosa (Sugar apple) evergreen  Plant Development is Plastic Totipotent – Ability of cells to differentiate to any other cell type Stem cells in animals, any cells in plants – Can happen to already differentiated cells – Undergo dedifferentiation (embryonisation) Tissue culture – Utilises totipotent ability to create sterile clones Allows plants to change based on the environment and regrow after herbivory damage Plant development is plastic – totipotent cells  Two Kingdoms Plant Kingdom – Included thallophytes (non-motile with a thallus) Bacteria, Algae Slime molds Fungi Bryophytes Vascular Plants Animal Kingdom  Six Kingdoms (Woese et al. 1990) System used in most textbooks – Protists are really several groups, not a clade or single lineage – Super group now abandoned Can be improved – Gene sequences and ultrastructure suggest several eukaryote super- groups differ from the current Kingdoms  Eukaryota Fungi – Non-motile, cell wall-bound, spore-bearing eukaryotes with a saprophytic or parasitic mode of heterotrophic nutrition Animals – Motile, heterotrophic eukaryotes, without cell walls Plants – Photosynthetic (mainly terrestrial) eukaryotes with cell walls Protists – None of the above, e.g., protozoans, for convenience Simplistic generalisations - exceptions – More accurate to think of lineages than simple descriptions What’s your muddiest moment so far? https://toughmudder.co.uk/blog/no-excuses/the-10-muddiest-moments-ever/  BIOL1020 Diversity of Life I Diversity and Evolution of Algae Algae are: Diverse, structurally simple aquatic photosynthetic organisms Polyphyletic - not a phylogenetic group Several discrete lineages or clades 20,000 to 30,000 species Oldest known algae Red fossil algae Bangiomorpha found in 1,200-million-year-old rocks in Canada.  Algal Classification In the past algae were classified based on several features: – Cell pigments – Energy storage – Motility, e.g., presence of flagella – Reproduction Modern classification makes use of molecular techniques: – Genetics Molecular studies show that algal groups are separate lineages  Algal Classification Blue-green algae Green Algae Euglenoids Red Algae Brown Algae Golden Algae Dinoflagellates Prokaryotic – Photosynthetic bacteria Cyanobacteria  Primary Endosymbiosis Prokaryotic cells arose first Early eukaryote engulfed smaller prokaryote Not digested – Not enough digestive enzymes? – Engulfed cell resistant to digestive enzymes? Cyanobacteria though to be ancestor of plastids Symbiosis – Protected inside of larger cell – Contribute photosynthates  Early eukaryote with membrane bound nucleus Engulfed prokaryote that would evolve into mitochondria Ancestor engulfed prokaryote that would evolve into plastids Mauseth 2017  Primary Endosymbiosis Clade with green, red algae and glaucophytes – Glaucophyte chloroplasts still produce a thin cyanobacterial wall – Red algae chloroplasts contain chlorophyll a (not b) and cyanobacterial pigment phycobilin – Green algae chloroplasts have no bacterial wall or phycobilin Green algae chloroplasts contain chlorophylls a and b and carotenoid accessory pigments – Similar to chloroplasts in true plants Green & Red algae closely related, arose from an initial primary endosymbiosis  Secondary Endosymbiosis Eukaryote engulfed another eukaryote – Euglenoids Early eukaryote engulfed green algae Green algae been reduced over time so mainly the chloroplasts remains – Brown algae Derived from early eukaryotes called heterokonts One or several endosymbiosis events engulfing red algae  Other algal groups arose from subsequent endosymbioses Chloroplast Evidence – No. of plastid membranes – Pigments – Plastid & mitochondrial genes Urry et al. 2021 Mauseth 2017  Euglenoids Dinoflagellates Diatoms Brown Algae Golden Algae Red Algae Green Algae Algae are not in one lineage Solomon et al. 2019  Eukaryote Domain Fungal Kingdom Animal Kingdom Other Kingdoms (Protists) Plant Kingdom – Archaeplastida – Plant kingdom including green & red algae and glaucophytes – Viridiplantae – Plant kingdom including green algae & land plants – Embryophyta – Plant kingdom including land plants and specific green algae  Eukaryote Domain Archaeplastida – Plant kingdom including green & red algae and glaucophytes – All have chloroplasts with 2 membranes – Other groups have chloroplasts with 3 or more membranes Indicates secondary endosymbiosis – Genetic studies indicate single origin of plastid  Eukaryote Domain Viridiplantae – Plant kingdom including green algae & land plants – Starch, cellulose cell walls, chlorophyll a & b and no phycobilin Embryophyta – Plant kingdom including land plants and specific green algae – All have embryos Urry et al. 2021 END If someone asked what you learnt today, what would you tell them?.....