Bis2CF10.Lecture15

Bis2CF10.Lecture15 - Lecture 15 ORIGIN OF LAND PLANTS Last:...

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Unformatted text preview: Lecture 15 ORIGIN OF LAND PLANTS Last: land plants in the TOL, life cycle in outgroups Nonvascular land plants (“bryophytes”) Vegetative innovations of land plants Reproductive innovations: alternation of generations Next: origin of vascular plants (tracheophytes) Red algae Glaucophytes Green plants Asteromonas Land plants unicellular flagellate Cyanophora loss of flagella chlorophyll b loss of phycobilins starch stored in chloroplast loss of peptidoglycan PLANTAE cellulose cell wall endosymbiosis with cyanobacterium (chlorophyll a, phycobilins, peptidoglycan in cp wall) two flagella Chlorophytes Streptophytes Spirogyra Chlorokybus Land plants Charales Coleochaete Mesostigma numerous chloroplasts branched filaments apical growth (>meristems) phragmoplast, plasmodesmata filaments (multicellularity) multilayered structure (lateral flagella) Klebsormidium chlorophyll b, starch in chloroplasts Land plants Basic events in eukaryotic sexual life cycle Diploid life cycle Multicellular diploid animal Spore = reproductive cell that is not a gamete Multicellular haploid organism Haploid life cycle Haploid life cycle Ulothrix (a chlorophyte) Haploid (n) spores Streptophytes Land plants zygote Land plants Charales Coleochaete oogamy branched filaments apical growth (>meristems) phragmoplast, plasmodesmata zygote surrounded by haploid cells numerous chloroplasts Early Devonian landscape (400 MY) Oldest fossils of land plants (Late Ordovician spores, cuticle) Middle Ordovician, 470 MYA Precambrian cyanobacteria (2 BY) “bryophytes,” nonvascular plants Outgroup streptophytes Land plants = Embryophytes Liverwort Moss Charales Hornwort Vascular plant (fern) Coleochaete cuticle rhizoids vegetative synapomorphies mycorrhizae alternation of generations: origin of sporophyte archegonia and antheridia sporangia air-dispersed spores phragmoplast, branched filaments, apical growth (meristems), oogamy LIVERWORTS rhizoids (“root-like” cells) epidermis with cuticle parenchyma 3-D mass of thin-walled cells Coleochaete rhizoids LIVERWORTS rhizoids (“root-like” cells) Liverwort cuticle and rhizoids Silurian fossil cuticle (440 MY) LIVERWORTS rhizoids (“root-like” cells) epidermis with cuticle Liverwort and symbiotic fungus (mycorrhizae = “fungus roots”) parenchyma 3-D mass of thin-walled cells rhizoids Outgroup streptophytes Land plants = Embryophytes Liverwort Moss Charales Hornwort Vascular plant (fern) Coleochaete cuticle rhizoids vegetative synapomorphies mycorrhizae alternation of generations: origin of sporophyte archegonia and antheridia Reproductive sporangia synapomorphies air-dispersed spores phragmoplast, branched filaments, apical growth (meristems), oogamy Spore = reproductive cell that is not a gamete Multicellular haploid organism Haploid life cycle Land plants Gametophyte (“gamete plant”) egg, sperm Alternation of generations Sporophyte (“spore plant”) Alternation of generations in nonvascular land plant (moss) Gametophyte (“gamete plant”) Gametangia (“gamete containers”) biflagellate SPORES Sporophyte (“spore plant”) Sporangium (“spore container”) Delay of meiosis Land plants = embryophytes Dawsonia: world’s largest moss (New Zealand) Alternation of generations in nonvascular land plant (moss) Gametophyte (“gamete plant”) Gametangia (“gamete containers”) spore tetrad sporopollenin wall SPORES biflagellate SPORES Sporophyte (“spore plant”) Sporangium (“spore container”) Delay of meiosis Land plants = embryophytes Late Ordovician tetrads (450 MY) Middle Ordovician, Argentina (470 MY) Rubinstein et al. 2010 Late Ordovician tetrads (450 MY) sporangium Wellman et al. 2003 Outgroup streptophytes Land plants = Embryophytes Liverwort Moss Charales Hornwort Vascular plant (fern) leaves on gpt stomata Coleochaete branched spt tracheids green sporophyte cuticle rhizoids mycorrhizae alternation of generations: origin of sporophyte archegonia and antheridia sporangia air-dispersed spores: sporopollenin wall phragmoplast, branched filaments, apical growth (meristems), oogamy ...
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